SUB-ORDER I.—SIMPLE-TOOTHED RODENTS.
Besides the characters derived from the number of incisor teeth above mentioned, several other peculiarities of structure seem to show the existence of a decided difference between the Simple-toothed and Double-toothed Rodents; but most of these are of a rather abstruse nature, and need not be noticed here, the most important additional distinctive characters of the former being that the bony palate is well developed, and that the fibula does not articulate with the calcaneum, or heel-bone; whereas in the Double-toothed Rodents the palate is reduced to a mere bridge between the portions of the upper jaw in which the teeth are inserted, and the fibula does articulate with the heel-bone.
The Simplicidentata include a great number of families, and various attempts have been made to group these under larger heads; but it must be confessed that, owing to the way in which the families approach one another, it is difficult to bring them together in sections capable of being very strictly defined. Certain broad principles of relationship are, however, generally recognised, and Mr. Alston represented these by placing the Simple-toothed families under three great sections, the first indicated by Mr. Waterhouse—the Squirrel-like, Mouse-like, and Porcupine-like Rodents.
The Squirrel-like Rodents have four molars on each side in the lower jaw, and either four or five in the upper. When the latter number is present, the foremost tooth is smaller than the rest. The fibula remains as a distinct bone through life, and is usually quite free, although sometimes attached to the tibia at the extremity. The upper lip is usually cleft, the muffle is small and naked, and the nostrils are comma-shaped, with the rounded part above. The zygomatic arch is formed chiefly by the process of the malar bone, which is not supported below by a continuation of the zygomatic process of the maxillary. The collar-bones are perfect. The tail is usually cylindrical and hairy.
The Mouse-like Rodents agree with the preceding in the characters of the upper lip, muffle, and nostrils, but they have the tibia and fibula completely united for at least the last third of their length. The zygomatic arch is slender, and the malar process rarely extends so far forward as in the preceding group and is generally supported below by a continuation of the maxillary process. The collar-bones are perfect, except in one very small family; and the tail is cylindrical, and although sometimes hairy, more commonly covered with scales arranged in rings. The number of molar teeth in this section varies from three to six[51]on each side in each jaw, but three is the most usual number.
TEETH OF THE TAGUAN.
TEETH OF THE TAGUAN.
The Porcupine-like Rodents, with one exception, have four molars on each side in both jaws; the fibula distinct throughout life; the upper lip rarely cleft; the muffle clad with a velvety coat of fine hairs; and the nostrils either S-shaped or straight. The zygomatic arch is stout, and the malar process does not advance far forward, nor is it supported below by the maxillary process.
SECTION I.—(SCIUROMORPHA.) SQUIRREL-LIKE RODENTS.
FAMILY I.—SCIURIDÆ.
This first family, which includes the true Squirrels and the Marmots, is distinguished from the rest of the section by the possession of five rooted molars on each side of the upper jaw (seefigure of the teeth on p. 85), the first being very small and sometimes deciduous, and four molars on each side of the lower jaw, and by the presence on the skull and zygomatic arch of small processes, indicating the posterior boundary of the orbits (seefigure of the skull on p. 82). The molars are tubercular, at least at first; but the summits of the tubercles are generally more or less worn down as the animal increases in age.
COMMON SQUIRREL.
COMMON SQUIRREL.
The true Squirrels, which may be regarded as the types of this family, are distinguished by their slender and graceful forms, and their long and generally bushy tails, the latter character having originated their classical name ofSciurus, as a compound of two Greek words, indicating their habit of carrying their tails thrown up, so as to shade the back. Our COMMONSQUIRREL(Sciurus vulgaris) may serve as a good example of this division of the family. It is too well known as a pet to need any detailed description; its elegant form and graceful movements, the rich brownish-red colour of its upper surface, contrasting with the white of the belly, and the beautifully-pencilled or tufted ears, which, combined with its bright black eye, give it such a lively appearance, must be familiar to every one. When full-grown, the Squirrel measures from eight to ten inches in length of body, and has a tail seven or eight inches long. British specimens are generally smaller than those from the Continent of Europe. It varies considerably in colour with the seasons, especially in northern regions; but even in Central Europe and in Britain the fur of the sides and back becomes mixed with a certain quantity of greyish-white hairs in the winter, whilst in Lapland and Siberia the whole upper surface acquires a grey tint at that season. In the summer also the ear-tufts diminish, or altogether disappear. In the Alps and Pyrenees, there is a variety having the back of a dark brown colour, speckled with yellowish-white. This has been described as a distinct species, under the name ofSciurus alpinus.
The Common Squirrel is a widely-distributed species. It is abundant all over Europe, except, according to Pallas, in the Crimea, and extends beyond the Ural Mountains through the whole length of Southern Siberia to the Altai and the Amoor region. It occurs in the Caucasus, and probably in Persia. Everywhere it haunts the woods and forests, living chiefly upon the trees, among the branches of which it displays the most astonishing agility. On the ground—to which, however, it does not often descend—it is equally quick in its movements. If alarmed under these circumstances, it dashes off to the nearest tree with lightning-like rapidity, and by the aid of its sharp claws rushes up the trunk till it has reached what it considers a safe elevation, when the little sharp face and bright eyes may be seen peeping at the intruder, apparently in triumph over his supposed disappointment.
The food of the Squirrel consists chiefly of nuts, beech-mast, acorns, and the young bark, shoots, and buds of trees. In eating the former articles, they are held in the fore-paws, which thus supply the place of hands, and the strong incisors soon make a way through the outer shells into the contained kernels, which alone are eaten; for in all cases in which the kernel is coated with a coarse brown skin (as in the common hazel-nuts), the Squirrel carefully removes every particle of this from the portions on which he feeds. The bark, buds, and young shoots of trees seem generally to be attacked by the Squirrel when he finds a deficiency of other and more congenial nourishment; but this is so regularly the case in the spring of the year, that these animals actually cause a great amount of damage to the trees in forest regions. Hence, not unnaturally, the Squirrel is regarded in forest countries as a most mischievous little animal, whose depredations are not to be condoned on account of its elegant appearance and lively habits. As another unamiable quality, may be mentioned its habit of plundering birds’ nests and eating the eggs, which appears to be established upon unquestionable evidence. In some northern regions the inhabitants turn their Squirrels to a more profitable use than putting them, as we so often do, into a sort of treadmill. In Lapland and some parts of Siberia, especially on the banks of the Lena, these animals are killed in great numbers for the sake of their grey winter-coats, which, however, are not equal in beauty to those of the north American Grey Squirrel.
The Squirrel passes the greater part of the winter in a torpid state, lying coiled up in some hole of a tree, where its long bushy tail is of service in keeping it warm and comfortable. On fine and warm days, however, it rouses itself from its slumbers; and, as if foreseeing the occurrence of such days, it lays up in the autumn stores of nuts, acorns, and beech-mast, upon which it can feed when it wakes during the winter. This winter provision is not laid up all in one place, but stored away in several different holes in trees surrounding the place of its own retreat.
Squirrels appear to be strictly monogamous, pairing for life, and constantly inhabiting the same dwelling. The young, three or four in number, are produced in June, and for their reception the parents prepare a very beautifully constructed nest, formed of interlaced moss, leaves, and vegetable fibres, which is placed either in the hole of a tree, or in the fork between two branches. The youngSquirrels are very carefully attended by both parents, and the family remains united until the following spring, when the young go out to find partners, and settle themselves in the world.
The Common Squirrel may serve as an example of the whole genusSciurus, which includes the ordinary Tree Squirrels, the species of which are very numerous, probably more than one hundred, and distributed over nearly all parts of the world. The species are most numerous in the warm Oriental regions, in India, and the countries and islands lying to the east of it, from which nearly fifty species have been recorded. The northern parts of the Old World only possess half a dozen species, but North America has about eighteen, many of which are considerably larger than the European Squirrel. The most striking of the North American species are the GREYSQUIRREL(Sciurus carolinensis) and the FOXSQUIRREL(Sciurus niger), both of which are abundant in the Atlantic States, and vary considerably in colour, presenting both grey and black individuals.
BLACK FOX SQUIRREL.
BLACK FOX SQUIRREL.
Besides the ordinary Squirrels, a considerable number of other species are arboreal in their habits, and, indeed, even more strictly so than the true Squirrels. These are the Flying Squirrels, as they are called, which may be at once distinguished from the others by the presence of a large fold of skin, extending along the sides of the body, and including the limbs as far as the wrists and heels (seefigure on next page). In the case of the Common Squirrels, it is observed that in performing leaps of any considerable extent the limbs are stretched out, and the long, bushy tail extended, so as to give the animal as large a surface as possible; but in the Flying Squirrels, as in the Flying Lemur (Vol. I., p. 344), when the limbs are extended laterally the folds of skin (patagia) become tightly stretched, and form a regular parachute, which seems to give the animal essential support in its most extensive leaps. The extent of this membrane is increased by means of a sort of bony spur, which articulates with the wrist.
The TAGUAN(Pteromys petaurista) is a large species, indeed, the largest of the whole family Sciuridæ. It measures about two feet long, and has a bushy tail of nearly equal length. Its ears are pointed, but not tufted, and its eyes are large and prominent. Its colour above is greyish-black, produced by a mixture of entirely black hairs with others having the tips greyish-white; beneath it is greyish-white. About the head and on the limbs the fur is tinged with brown or chestnut brown, and the lateral folds are sometimes of the latter colour, sometimes blackish-brown above and grey beneath. The tail is rounded in its form.
This species inhabits the peninsula of India and Ceylon, Malacca and Siam, where it is found only in the forests, living in trees, either singly or in pairs. Its activity is chiefly nocturnal, in which respect it differs from the ordinary Squirrels. During the day it sleeps in the holes of trees, but at night it comes forth, climbing and leaping with the greatest rapidity about the trees on which it lives. While thus engaged the lateral membranes are loosely folded at the sides of the body; but from time to time the Squirrel wishes to pass from one tree to another at some distance, and then it ascends to a considerable elevation and springs off, at the same time extending all four limbs as much as possible, when the tightly-stretched folds of skin lend the body a support, which enables it to glide through the air to some distance, although it seems always to alight at a lower level than that from which it started. During these aerial excursions the long bushy tail serves as a sort of rudder, and enables the animal even to change its course during flight. Of the habits of the Taguan very little is known. It appears to feed upon fruits, and is exceedingly shy and fearful. Of a nearly-allied species which he observed in China, Mr. Swinhoe says that the nest, which was placed high up in a large tree, measured about three feet in diameter, and was composed of interlaced twigs, and lined with dry grass. It contained only a single young Squirrel; but this might be exceptional.
TAGUAN.
TAGUAN.
Some nine or ten additional species of the genusPteromys, which includes the Flying Squirrels with cylindrical tails, are found in the forest regions of India and of the countries to the east of that peninsula, including China, Formosa, and Japan. The same region also harbours three or four species of another kind of Flying Squirrel, in which the long hairs of the tail are arranged in two rows, and the tail is flat instead of cylindrical. These animals, to which the name ofSciuropterushas been given, are, however, more numerous in the north, where their distribution extends from Lapland and Finland, through Siberia, to Northern China and Japan. Squirrels of this genus also occur over the whole continent of North America and as far south as Guatemala. The best known of the Old World species is the POLATOUCHE(Sciuropterus volans), which inhabits the north-eastern parts ofEurope and nearly the whole of Siberia. It is an elegant little creature, about six inches in length, and with a broad, flat tail, rather shorter than the body: as, indeed, is the case in all theSciuropteri. Its silky coat is in summer of a tawny brown on the upper surface, darker on the flying membrane and the outsides of the limbs, beneath pure white; whilst the tail is greyish above and light rusty red beneath. In winter the fur becomes longer and thicker, and appears of a silver grey colour on the upper surface. The Polatouche lives in the birch woods, or in places where pines, firs, and birches grow intermingled; but the presence of the birch seems to be a necessity of its existence. It is met with singly or in pairs, but always on the trees, sleeping during the day in its nest or in the hole of a tree, and coming forth at dusk to climb and leap about the branches with great agility. In going from tree to tree by the aid of its lateral membranes, it is said to cover distances of twenty or thirty yards with ease, always, however, taking its leap from the highest branches of the tree it starts from, and alighting at a considerably lower level. Its food consists of nuts, seeds, berries, the buds, young shoots, and catkins of the birch, and the young shoots of pines and firs. The nest is made in the hole of a tree, carefully lined with soft moss and herbage. Like the Common Squirrel, the Polatouche sleeps through the cold weather, but wakes up from time to time and goes out in search of food.
POLATOUCHE.
POLATOUCHE.
This group of Flying Squirrels is also represented on the North American continent. The number of species seems rather uncertain, some authors making it two, others four; while Mr. J. A. Allen regards all the North American Flying Squirrels as belonging to a single species, which varies greatly in size in different localities. This species is the ASSAPAN(Sciuropterus volucella), one of the smallest of its family, the length of its head and body being only from four and three-quarters to seven and a half inches; the smaller specimens (var.volucella) being found in the more southern States, and even as far south as Guatemala; and the larger ones (var.hudsonius) in more northern localities. In its habits this elegant little Squirrel resembles the Polatouche, but appears to be more sociable. It thrives well in confinement.
Besides these Tree Squirrels, a few species of the Sciurine sub-family live upon the ground. In Abyssinia and in other parts of Africa some curious animals, forming the genusXerus, are found, distinguished by their very small ears, longish limbs, and the singular texture of their hair, which scantily clothes the skin and generally takes the form of flattened spines. They have a slender body, a pointed head, and a longish tail. These animals live in elevated forest regions, and even upon comparatively barren steppes, where they burrow in the ground under rocks, or among the roots oftrees and bushes. They are diurnal, and feed chiefly upon buds and herbage, but also devour small birds, eggs, and insects. The best known species (Xerus rutilans) is about twenty inches long, of which the tail makes about nine inches. Its colour is reddish-yellow above, becoming paler on the sides, and whitish below.
COMMON CHIPMUNK.
COMMON CHIPMUNK.
The true GROUNDSQUIRRELS(Tamias) are distinguished from the rest of the Squirrels (Sciurinæ), and approach the Marmots, which form a second sub-family of Sciuridæ. Like some of the latter, they possess large cheek-pouches opening into the mouth. The ears in this genus are short; the fourth toe of the fore feet is longer than the rest, as in all the Sciurinæ; the limbs are short, and nearly equal in length; and the tail is shorter than in the true Squirrels. In general form and appearance, however, the Ground Squirrels greatly resemble the latter, except that they are rather stouter in the body. Four species of this group inhabit the continent of North America, where they are known as Chipmunks; and one of these, according to Mr. J. A. Allen, is identical with the only known Old World species (Tamias asiaticus), which is found in North-eastern Europe and across Northern Asia, as far as the mouth of the Amoor, North China, and Japan. This species, which goes by different names in the different localities which it inhabits, and the COMMONCHIPMUNK(Tamias striatus) of the United States, agree very closely in all respects, and are exceedingly pretty little animals, with light-coloured fur adorned with darker stripes, varied in the case of the Chipmunk with streaks of white. They are from eight to ten inches long, including the tail. These animals live in burrows in the ground, and feed upon nuts, acorns, grain, and other seeds of various kinds, of which they lay up great stores in the autumn, carrying home their provisions in their cheek-pouches, which they stuff as full as they can hold. In this way they do no small damage to cultivated grounds near their haunts, plundering the corn and maize fields very freely; over eight pounds of corn in the ear are often found in the granaries of the Siberian form. The burrow is made deep enough to protect the animals from frost in winter, and the sleeping chamber contains a large nest of leaves and grass, in which several individuals, probably the parents with their grown-up family, sleep through the cold weather; but it must be remarked that their torpidity is very imperfect, and that they have frequent recourse to the supplies of food which they have stored up during the summer and autumn in separate chambers at the ends of lateral passages. These stores are so large that they generally greatly exceed the wants of the provident little animals,and in the spring the residue is greedily devoured by Wild Pigs and Bears. Even the poorer human inhabitants of the countries frequented by the Ground Squirrels do not disdain to eke out their scanty means of subsistence by plundering the hoards of these animals. Many of them perish in severe winters, great numbers are destroyed by man, by the smaller Carnivora, and by birds of prey, but, nevertheless, they manage to hold their own, in consequence of the great fertility of the females, which produce several young twice in the year, namely, in May and August. At pairing time the males fight violently.
MOLAR TEETH OF THE MARMOT.
MOLAR TEETH OF THE MARMOT.
From the Ground Squirrels we pass, by a perfectly natural transition, to the MARMOTS(Arctomyinæ), the second sub-family of Sciuridæ. These animals differ from the preceding forms by their broader incisors, shorter tail, and stouter form of body, and by having the third finger longer than the rest. The first upper molar, also, is larger and more persistent than in the Squirrels, and the other molars differ in structure (seefigure). The Marmots are all terrestrial animals, living and storing provisions in burrows, which they dig in the ground, and they are strictly confined to the northern parts of the two hemispheres.
STRIPED SPERMOPHILE, OR GOPHER.
STRIPED SPERMOPHILE, OR GOPHER.
BURROWS OF THE PRAIRIE DOG.
BURROWS OF THE PRAIRIE DOG.
The nearest approach to the Squirrels is made by the SPERMOPHILES(Spermophilus), several species of which occur in North America from Mexico to the Arctic regions, but never to the east of the great central prairie region; whilst in the Old World their domain extends from Silesia, through Russia, and across Asia, to the Amoor and Kamstchatka. The Spermophiles are Squirrel-like in form and have rather short tails, but in the American species this organ is generally longer than in those of the Eastern continent. On the thumb the claw is either very small or altogether wanting; the two series of molars are nearly parallel, and the mouth is furnished with large cheek-pouches. The ears are very small. These animals live in society, and prefer a dry, sandy, or loamy soil, in which they can easily make their burrows, which terminate in a chamber lined with grass and herbage, and have, besides, side-chambers, in which provisions can be stored for winter use. Like the other species of the family, the Spermophiles pass the winter in a state of partial torpidity. In the summer they are exceedingly lively and playful. Their food consists of roots, berries, and seeds of various kinds, and their winter stores of these articles are carried into the burrows intheir large cheek-pouches. The females are very prolific, producing from four to eight young at a birth, and in some cases even as many as ten have been found. The commonest and most widely distributed of the North American species is the STRIPEDSPERMOPHILE, or GOPHER(Spermophilus tredecimlineatus), a pretty little creature of from six to eight inches long, usually of a chestnut brown colour with seven yellowish-white lines running along the back and between these six rows of small squarish spots of the same colour. This species extends its range from the Red River in Canada southwards as far as Texas, and is common on the prairies east of the Mississippi. This and some other species of the genus are said to be very carnivorous in their habits, preying upon small birds and mammals; and the Gopher was even described as feeding upon the flesh of Bisons, which it found lying dead on the prairies. The other American species are more local in their distribution; four of them occur in Mexico, and one of these is only known from that country. Of the Old World species the best known is the SISEL, or SUSLIK(Spermophilus citillus), which is abundant in Central andEastern Europe and in Siberia. Several other species are known from Asia Minor, Siberia, and Central Asia.
The BARKINGSQUIRRELS, or PRAIRIEDOGS, of which two species (Cynomys ludovicianus,seefigure on p. 81, andC. columbianus) are found in the United States of America, are of a stouter form than the Spermophiles, and have the ears and tail short. The claws are well developed on all the toes of the fore feet, the cheek-pouches are shallow, and the two rows of grinding teeth converge towards the back of the mouth. These animals are peculiar to North America, where the former inhabits the prairies east of the Rocky Mountains, and the latter is found on the plains of the Columbia river, and in other parts of the western territories as far south as New Mexico. The best known of the two species is theCynomys ludovicianus, to which the name of the PRAIRIEDOGwas first applied: this name being given to it from a fancied resemblance of its voice to the barking of a small Dog. It measures about a foot in length, and its tail is about four inches long. Its colour on the upper surface is reddish-brown, variegated with grey, and with a few scattered black hairs; the tail is flattened, and brownish-black towards the end, and the lower surface is brownish or yellowish-white. These animals live together in great societies, especially upon those portions of the prairies where the so-called buffalo-grass (Sesleria dactyloides) grows most luxuriantly, this grass and succulent roots constituting their chief food. They live in burrows, which they dig in the ground at a distance of twelve or fifteen feet apart; a hard-beaten path runs from burrow to burrow, and would seem to give evidence of the sociable disposition of the animals; and at the mouth of every burrow there is a little hillock, formed by the earth thrown out of it, which serves the occupant as a watch-tower. These burrows are usually so numerous upon favourable pieces of ground that the space occupied by them is quite populous, and presents a scene of considerable animation when the inhabitants are out in the pursuit of their business or their pleasure, and hence they are in common parlance spoken of as “towns” or “villages.” Their curious appearance is heightened by the almost constant presence in them of numerous small Owls, of the species known as the Burrowing Owl (Athene cunicularia), a widely-spread species, which in some places digs its own subterranean habitation, but on these prairies saves itself the trouble by taking possession of the deserted abodes of the Prairie Dogs. These birds are diurnal in their habits, and are to be seen mixed up with the Prairie Dogs in their settlements. Another inhabitant of the burrows is the Rattlesnake; and some of the earlier observers thought that the Prairie Dogs, Owls, Rattlesnakes, and some other animals, such as Horned Frogs and an occasional Tortoise, occupied the same burrow, and lived there on the most amicable footing. Unfortunately, this paradisaic picture is an imaginary one. It is true that the Rattlesnake does take up his abode in the Prairie Dog’s burrows, but he either selects a deserted one, or dispossesses, and perhaps devours, the rightful owner; and his object in his residence among the lively little Marmots is anything rather than peaceful, as they constitute his favourite food. The little Burrowing Owl has also been said by some writers to feed on the young Prairie Dogs; but this is not proved, and the food of the Owls is known to consist chiefly of Grasshoppers and Crayfish. According to the latitude in which they live, the Prairie Dogs seem to be more or less subject to torpidity during the winter.
The true MARMOTS(Arctomys) are nearly related to the Prairie Dogs. They are stout in the body, have a short tail, and a rudimentary thumb with a flat nail; and are either entirely destitute of cheek-pouches or have mere indications of those organs. The rows of molar teeth are placed nearly parallel to each other in each jaw. The skull is broad and flat above, with a depression between the orbits; and the post-orbital processes are larger than in any other Sciuridæ. The Marmots are confined to the Northern hemisphere, but over it they are widely distributed in both continents. Of the Old World species, the best known are the BOBAC(Arctomys Bobac) and the ALPINEMARMOT(A. Marmota), of which the former extends from the south of Poland and Galicia over the whole of Southern Russia and Siberia to the Amoor region and Kamstchatka, whilst it is found in elevated situations as far southward as Cashmere, Tibet, and the Himalayas; and the latter inhabits only the higher regions of the Alps, Pyrenees, and Carpathians. In North America the common species is the WOODCHUCK(Arctomys Monax), the distribution of which is from the Carolinas northward to Hudson’s Bay, and westward from the Atlantic coast to Missouri, Iowa, and Minnesota; the Rocky Mountain region is inhabited by a distinct species (A. flaviventer); and a third very large species, the HOARYMARMOT, or WHISTLER(A. pruinosus), which measures from twenty-three to twenty-five inches in length of body, appears to be most abundant in the north-western parts of the continent, and is said to range northward as far as the Arctic Circle. The Marmots live usually in large societies in extensive burrows, which they form underground; and in some localities, as on the great plains of Russia and Siberia, their dwelling-places are described as producing a remarkable effect, owing to the multitude of little hillocks formed by the earth thrown out of their burrows. During the summer they are in a state of constant activity, playing and running about in search of food in the neighbourhood of their dwellings. The winter they pass in a state of torpidity, in a comfortable chamber lined with soft herbage, and protected from the outside cold by the closure of the main passage leading into their abode. For a time after their retirement for the winter they continue active in their domicile, and feed upon the stores of food which they have laid up during the summer; and as a preparation for their winter sleep, they become exceedingly fat during the autumn. The Marmots are the largest members of their family, and, indeed, some of them may be reckoned among the larger Rodents. The Alpine Marmot measures more than twenty inches in length, and the Bobac about fifteen inches, exclusive of the tail.
ALPINE MARMOT.
ALPINE MARMOT.
FAMILY II.—ANOMALURIDÆ.
Some curious African animals, closely resembling the Flying Squirrels, and at first regarded as belonging to that group, were formed by Mr. Waterhouse into a distinct genus, which he calledAnomalurus, in allusion to the peculiar characters presented by their tail. This organ, which is long and well clothed with hair, although not so bushy as in the true Squirrels, has on the lower surface of its basal portion a double series of horny scales, which project from the skin, and probably serve to assist the animal in climbing upon the branches of trees.
Besides this peculiarity, these animals exhibit certain other characters which have induced modernzoologists to separate them from the Squirrels as a distinct family. Thus, the post-orbital processes are wanting, or nearly so; the infra-orbital openings are large; the molar teeth are four in number on each side, above and below, nearly equal in size, and not tubercular, but with a flat surface, crossed by transverse loops of enamel; and the palate is contracted in front and deeply notched behind. In the skeleton we find sixteen pairs of ribs, whereas in the Squirrels there are only twelve or thirteen pairs; and the internal anatomy, first described by Mr. Alston, is very peculiar. The flying membrane is quite as largely developed as in the Flying Squirrels, and is in the same manner extended from the wrists to the heels, and further supported by cartilaginous spurs starting from the fore limbs; but, whilst in the Flying Squirrels this spur springs from the wrist itself, in the Anomalures it projects from the elbow, and thus produces a still greater extension of the membrane. The ears are well developed, the eyes large, and the general aspect both of head and body completely squirrel-like. Six species of this family have been described, all from the West Coast of Africa. One of them occurs in the island of Fernando Po. The species figured (Anomalurus fulgens) is from the Gaboon. It is a handsome little creature, of a bright reddish colour, paler below, and having a small white spot between the ears. Its length is fourteen inches, and its tail is seven inches long. In some of the other species the tail is as long as the body. Of the habits of these animals little is positively known, but they are said to feed upon fruits. They probably resemble the Flying Squirrels in their general mode of life.
FULGENT ANOMALURE (From theProceedings of the Zoological Society).
FULGENT ANOMALURE (From theProceedings of the Zoological Society).
MOLAR TEETH OF THE ANOMALURE.
MOLAR TEETH OF THE ANOMALURE.
FAMILY III.—HAPLODONTIDÆ.
This is another small family, smaller even than the preceding one, for it includes only a single known species, limited in its range to the western coast of North America. This is the Sewellel, a little Rodent, first observed by the American travellers, Lewis and Clarke, in 1805 or 1806, described in 1814 by Rafinesque under the name ofAnisonyx rufa, and afterwards, in 1829, by Sir John Richardson, as the type of a new genus, asAplodontia leporina. This generic name has been corrected, in accordance with its derivation, by more recent writers, toHaplodon, from which the name of the family has been formed.
In this animal there are five molars in the upper and four in the lower jaw; the first upper molaris very small, and all these teeth are rootless, simple, and prismatic, the surface of each tooth being surrounded by a mere border of enamel. The skull is very flat, very wide behind, and furnished with large zygomatic arches; between the orbits and in front it is much contracted, and there are no post-orbital processes. In the lower jaw the angular portion is twisted so as to form a horizontal ridge. The body is stout and clumsy, the tail very short, and the claws of the fore feet (which are five-toed, as well as the hind ones) are very powerful; in fact, as Dr. Coues says, “The whole organisation, viewed externally, indicates terrestrial and highly fossorial habits.”
The SEWELLEL(Haplodon rufus) is about a foot long, with a tail of an inch or an inch and a half; its colour is brownish, with an intermixture of black hairs, lighter and more greyish below. The whiskers, claws, and upper surface of the feet are whitish, and the incisor teeth yellow. It inhabits the Washington and Oregon territories, from the Rocky Mountains to the shores of the Pacific, and extends also into the southern portions of British Columbia and the upper parts of California.
The Sewellel is described as having very much the same habits as the Prairie Dog, living in society, burrowing very readily in the ground, and feeding on roots and berries. Their companies, however, seem to be much smaller than those of the Prairie Dog, and they are said chiefly to frequent spring-heads in rich, moist places. They are described as having the curious habit of neatly cutting off some herb or plant, which, when packed in bundles, they lay out and expose to the sun to dry; this is probably for the purpose of storing for winter consumption. It seems to be uncertain whether the Sewellel is torpid during the winter, but probably in this respect it varies according to local conditions or the coldness of the seasons. Dr. Suchley believes that the Sewellel has several litters of young during the season. The Indians trap them, and esteem them very highly as food. Cloaks or blankets are made of their skins, which are sewn together with fibres derived from the sinews of the Elk and Deer. A robe described by Sir John Richardson was composed of twenty-seven skins.
FAMILY IV.—CASTORIDÆ.
Unlike as the Beaver may be to a Squirrel, it yet presents many characters which prove that its nearest affinity is to the animals which compose the group Sciuromorpha. This relationship has indeed been overlooked by many zoologists, but Mr. Alston and Mr. Allen have clearly shown that Professor Gervais was right in placing the Castoridæ in close juxtaposition with the Squirrels. The peculiarities which make the apparent discrepancy so striking are indeed chiefly those by which the Beaver is adapted to an aquatic life.
MOLAR TEETH OF THE BEAVER.
MOLAR TEETH OF THE BEAVER.
The Beaver, which is the sole living representative of this family, is a more powerful animal than any of the preceding, and his incisor teeth and the means of working them are especially well developed. The head is large and the skull massive, and furnished with a distinct median (sagittal) crest for the insertion of the strong muscles which move the lower jaw. There are no post-orbital processes. There are four molars on each side in each jaw, and these are nearly similar in size and structure; but, contrary to what we have seen in the preceding groups, the first molar is the largest, and the others diminish in size towards the hinder end of the row. The series of teeth in the two sides of the mouth converge toward the front; and the teeth themselves, which are for a long time rootless, and only close up to form a simple root when the animal grows old, show three folds or loops of enamel on one side, and a single fold on the other: the three folds entering from the outer surface of the tooth in the upper jaw, and from its inner surface in the lower.
The general form is stout and heavy, especially in the hinder parts; the tail is of moderate length, broad, flattened, and covered with a scaly skin; the feet are all five-toed, the fore pair considerably smaller than the hinder, but all well furnished with claws, and the hinder pair fully webbed to the extremities of the toes. The wrist has a large ossicle, in addition to those usuallycomposing that part of the body. The eyes are small, have the pupil vertical, and are furnished with a nictitating membrane; the ears are small and short, and their antitragus can be so applied to the head as almost entirely to close the auditory aperture; and the nostrils are also so arranged as to be capable of closing.
BEAVER.
BEAVER.
The Beaver is usually about two feet and a half long, and is, therefore, one of the largest of the Rodentia, except the Capybara. The tail, which is flattened above and below, and of an elongated oval form, measures about ten inches. The muffle is naked; the ears scaly; the soles of all the feet are naked, and their upper surfaces clothed with hairs; and the second toe of the hind feet is usually furnished with a double claw, the additional one being placed beneath the other. The general colour of the fur is reddish-brown on the upper surface, lighter and greyish below. The colour varies a little in different individuals, and appears to become darker, or even blackish, in northern localities. White or pied individuals are not uncommon. The Beaver appears to increase in size for some years after it has attained maturity. Mr. Allen says that in America “two-year-old Beavers generally weigh about thirty-five to forty pounds, while very old ones occasionally attain a weight of upwards of sixty.” The size of the skull seems to increase throughout life; the thickness and density of the bones also increase, and the ridges for the attachment of the muscles become stronger in old individuals.
The Beaver is, or has been, distributed generally over all the northern parts of the Northern hemisphere, especially in the forest regions. Formerly it ranged over the whole of Europe, includingthe British islands, where there is historical evidence of its former existence, besides the skulls and bones which have been found in various places, but especially in the Fen lands. At present the animal appears to be completely exterminated in the southern parts of Europe from France southwards, with the exception of a small colony on the Rhone, which we believe is still in existence; and only a very few individuals survive in Germany, where they are found on a tributary of the Elbe, and in one or two other places. In some parts of Poland, Russia, and Austria, and in the Scandinavian peninsula, they still, to a greater or less extent, hold their ground; and in Asia they abound about the rivers of Siberia, and in the streams which flow into the Caspian Sea. In North America Beavers formerly abounded from Texas, and, according to manuscript evidence cited by Mr. Allen, even from Mexico, northward to the extreme limit of forest growth, and from the Atlantic to the Pacific coast. The constant pursuit to which the animals were subjected, in consequence of the demand for their skins, greatly diminished their numbers, and in many localities altogether exterminated them; but they still occur over a very large extent of the North American continent, especially in the western territories, where they are even abundant in some of the wilder parts.
In the preceding statements we have spoken of the Beaver as forming a single species; but it has long been a moot question with zoologists whether the Beavers of the Old and New Worlds were or were not specifically identical. The external differences are very slight, and those observed in the skull, upon which most stress has been laid, do not appear to be of sufficient importance for the separation of the animals as distinct species. They consist chiefly in the greater breadth of the anterior portion of the skull, including the inter-orbital space; the extension farther back of the nasal bones, the greater size and depth of the basilar cavity and the more anterior position of the auditory bullæ, in the European Beaver; but the examination of large series of specimens has proved that the skulls from both hemispheres present many exceptions, in which one or more of the peculiarities which they ought to exhibit do not occur: a circumstance which of necessity greatly invalidates the distinction founded upon such characters. Dr. Ely sums up the results of an extended investigation in the following words:—“The extremes of difference, in their aggregate, on the one side and on the other, are sufficiently striking to justify us in regarding them as varieties of one and the same species; while the want of constancy in these peculiarities suggests the inference that these variations are due to long separation of the races, and to accidental causes, rather than to original diversity of the stock.” The Beaver may thus be regarded as a species with two geographical forms (varieties or sub-species), viz.,Castor fiber, var.europæus, andCastor fiber, var.canadensis.
So much has been written upon the habits of the Beaver, that the following short statement will suffice to give the leading facts in the natural history of the animal, the accounts of the marvellous sagacity of which, given by the older writers, have, perhaps, invested it with an exaggerated interest.
In populous countries the Beaver is contented, like the Otter, with a long burrow for his residence; but in the wilder regions of Siberia and North America his dwelling-place is a much more complicated affair. But even in these regions, according to some authorities, a certain number of Beavers—always males—show a lazy unwillingness to take part in the common labours of the colony, and these, as idlers, are expelled from the community, often with rather severe treatment, and then take up their abode by themselves in holes, which they dig out in the banks of rivers, whence they are called “terriers.” On the other hand, it would appear that the building instinct which is so remarkably manifested by the Beaver is not always extinct even in those which inhabit populous countries, for we have a most interesting account from M. Meyerinck of the construction of a lodge, and even of a dam, by the colony of Beavers on a tributary of the Elbe.
In North America, from which we have the fullest accounts of the habits of the Beavers, these animals select for their habitation some small stream running through a locality well covered with trees, especially willows, birches, and poplars, upon the bark of which they chiefly feed. These trees they cut down with their powerful incisor teeth, usually selecting those from the thickness of a man’s arm to that of his thigh, but sometimes even felling trunks eighteen inches in diameter. The operation, which at first sight would seem to be a rather difficult one for an animal like the Beaver to perform, is effected by gnawing all round the trunk for a certain distance, and gradually working deeper and deeper into its substance in the middle of the part attacked, until at length the tree standsupon quite a slender piece of wood, with the trunk both above and below this tapered off into the form of two cones, united by their apices. The work is done as sharply and neatly as if the wood had been cut away by a chisel; and the animals are said to have the sagacity to weaken the trunk more on the side that looks towards the water than on the opposite side, by which means, when it falls, it will generally do so in the direction of the water, which materially facilitates the further operations of the Beavers. The quantity of trees cut down by them in this way is very great, so that in the neighbourhood of a Beaver encampment the ground is everywhere full of the stumps which they have left.
These tree trunks are then cut up into lengths of five or six feet, which, after their bark has been stripped off and eaten, are employed in the formation of a lodge, to serve as a shelter for the company of Beavers forming it. Access to the lodge is obtained by means of several subterranean passages, which always open under water, and lead up into the chamber occupying the interior of the lodge. The lodge is usually of an oven-like shape, and is built close to the edge of the water; its walls are very thick, and composed of the above-mentioned trunks of trees, plastered over with mud, clay, &c., mixed with grasses and moss, until the whole fabric measures from twelve to twenty feet in diameter, and forms a hill some six or eight feet high. The larger lodges are in the interior about seven feet in diameter, and between two and three feet high; and the floor of this spacious chamber is covered with fine chips of wood, grasses, and the soft bark of trees, which serve to form the beds of the occupants. Occasionally the lodges are said to contain store-rooms. In front of the lodge, according to Audubon, the Beavers scratch away the mud of the bottom until they make the water deep enough to enable them to float their pieces of timber to this point, even when the water is frozen; and, communicating with this, a ditch surrounds the lodge, which is also made so deep that it will not readily freeze to the bottom. Into this ditch, and the deep water in front of the lodge, the passages by which access to the water is obtained always open, and thus the inhabitants can at any time make their way out when their business requires them to do so. In the neighbourhood of the lodge the timber cut into lengths, as above described, is piled up, so as to furnish a supply of food as it is required; and the pieces of timber, after being stripped of their bark, are usually employed by the Beavers either in repairing their lodges or in constructing or strengthening the dams which they very frequently throw across the streams haunted by them. These dams, which are destined to keep the water of variable streams up to the necessary height for the convenience of the Beaver, are wonderful pieces of work, and almost justify the marvellous stories told of its intelligence and sagacity by the older writers. They are often of great length—sometimes 150 or 200 yards and more—and run across the course of the brook inhabited by the Beavers—sometimes in a straight line, sometimes in a curved form, according to peculiarities in the ground or the stream, and the exigencies of the engineers. They are composed, like the lodges, of lengths cut from the trunks and branches of trees, filled in with smaller sticks, roots, grasses, and moss, and all plastered with mud and clay in a most workmanlike manner, until the whole structure becomes quite water-tight. Their height is from six to ten feet, and their thickness at the bottom sometimes as much as double this, but diminishing upwards by the slope of the sides until the top is only from three to five feet wide. These dams convert even small rivulets into large pools of water, often many acres in extent; and in districts where Beavers abound these pools may occupy neatly the whole course of a stream, one above the other, almost to its source. Their use to the Beavers, as constantly furnishing them with a sufficiency of water in which to carry on their business, and especially to float to their lodges the tree trunks necessary for their subsistence, is easily understood; but it is a more remarkable circumstance that by this means the Beavers exercise a considerable influence upon the external appearance of the locality inhabited by them, which may persist even long after they have themselves disappeared. In and about the pools the constant attacks of the Beavers upon the trees produce clearings in the forest, often many acres in extent; at the margins of the pools the formation of peat commences, and under favourable circumstances proceeds until the greater part of the cleared space becomes converted into a peat-moss. These peaty clearings are known as Beaver-meadows, and they have been detected in various countries where the Beaver is now extinct.
As in the case of the majority of Rodents, the chief activity of the Beaver is nocturnal; and it is only when driven from its lodge by a high flood, or in the wildest and most sequestered localities, thatit goes about during the day. It swims quickly, but entirely by the agency of the hind feet, the fore feet being used chiefly for carrying and building operations, and for conveying the food to the mouth. Before diving, it is said to slap the surface of the water with its tail, producing a sound that may be heard at a considerable distance. On land it sometimes travels a good way in the warm season, and is then stated to indulge in a change of diet, feeding upon roots and fruits, and sometimes upon corn. The roots of the water-lily (Nuphar) are also said to constitute part of its food. The Beaver is hunted—but less now than in former years—for the sake of its skin, the soft under fur of which was much used in the manufacture of hats. It is asserted that the flesh is very good, but according to some authorities, only certain parts of it are palatable; and Audubon declares that the tail, which is regarded as a peculiarly choice morsel, closely resembles marrow, and is so rich that only those whose stomachs are incapable of being upset by greasy food can eat more than a very little of it.
The Beaver has been hunted not only for its fur, but also, and from time immemorial, for the sake of a peculiar secretion produced by it, which, under the name ofCastoreum, has been for many centuries a highly-esteemed medicament. This substance is secreted in a pair of glandular pouches, situated in the inguinal region of the male Beaver; and it would seem that it was almost entirely in order to procure these that the ancients hunted this animal. Even in connection with this they had wonderful tales to tell of its sagacity: as how that, when it was pursued and found itself unable to escape, it would throw itself upon its back, as if to invite the hunter to take what he wanted and spare its life. Nay, some ancient writers seem to have believed that the Beaver would go the length of biting off its own castoreum glands, and leaving them for the hunter to pick up! Castoreum contains some volatile oil and resin, and a peculiar crystallisable substance called castorine; it is used in medicine as a stimulant, and seems to act especially on the nervous system, but is not much employed nowadays. Its odour, which appears to spread over a considerable space, is described as being very attractive to other Beavers. Audubon states that it is used for this reason as a lure by the American trappers.