Fig. 258.
Fig.258.—A, left arm ofHapalemur griseus♂.a, Teat;b, spines on arm gland;c, tactile bristle. B, left foot ofNycticebus tardigradus. 1 to 5, Pads upon sole of foot. (After Sutton, and Mivart and Murie.[399])
The Lemurs have at the present time a most remarkable distribution. There are altogether about fifty species, referable to seventeen genera. Thirty-six species are confined to Madagascarand to some small neighbouring islands. The rest occur in the Ethiopian and in the Oriental region. The rest of the world is at present totally without Lemurs, though, as will be seen in the sequel, the order was more widely spread over the globe in past times.
Fam. 1. Lemuridae.—This family can be usefully subdivided into four sub-families.
Sub-Fam. 1. Indrisinae.—This sub-family is limited to Madagascar, and has been exhaustively treated of by M. Grandidier and Professor Milne-Edwards in theHistoire de Madagascar. These Lemurs contrast with others by the large size of the hind- as compared with the fore-limbs. The ears are short. The tail varies in length. The thumb is but slightly opposable, and the toes are webbed. Correlated with the first two of these characters, these Lemurs when upon the ground progress by means of the hind-limbs, holding their arms above their heads. The number of teeth is reduced, the total being thirty. The formula[400]is I 2/2 C 1/0 Pm 2/2 M 3/3. The colon or large intestine, as figured by Milne-Edwards, has a remarkable watch-spring-like coil, highly suggestive of the Ruminants and of certain Rodents. This, however, is only inPropithecusandAvahis. The caecum in this sub-family is specially large. The brain is characterised by the comparatively slight development of the angular fissure inPropithecusandAvahis; it is in them anterior in position. InIndrisit is moreS-shaped and larger as inLemur. The parieto-occipital fissure is fairly well developed, so too is the antero-temporal.
The genusIndrishas more pronounced external ears than have the two other genera of the sub-family. The tail is rudimentary. The incisors of the upper jaw are sub-equal and set close together, those of the lower jaw have marked longitudinal ridges upon the outer surface, which suggestsGaleopithecus(see p.520). The molars are quadricuspidate. There is but a single species,I. brevicaudata, which is of a black colour, diversified with white upon the rump and the limbs. The term "Indri"[401]means, as does "Aye-aye," "look." One of the native names for theanimal, "Amboanala," signifies "dog of the forest," and is derived not only from the woeful howls of the creature, but from the fact that in certain parts of the island it is used as a dog to chase birds.
These howls are largely effected by means of a laryngeal pouch, which is described as different from that of Apes; the mechanism must also differ from that ofMegaladapis, inasmuch as the lower jaw is not deep as in that extinct Lemur. The Indri is the largest of Lemurs, measuring about two feet in length. It is arboreal and social, travelling in large companies. As is the case with thePropithecus, the natives of Madagascar hold the Indri in awe and veneration. It is curious that the name Lemur or ghost is peculiarly applicable to the Indri or Babakote in another sense from that which led to its adoption by Linnaeus. The natives, in fact, believe that men after death become Indris. Naturally, therefore, these Lemurs have reaped the advantage of this superstition in almost perfect immunity from destruction. Their "long-drawn-out, melancholy cries" are probably at the root of much of the ghostly terrors which they inspire.
The genusAvahis[402]has but a single species,A. laniger, which is the smallest of this sub-family. It is a foot long without the tail. The Avahi has a long tail (15 inches in length) likePropithecus. The outer incisors are larger than the inner, thus differentiating the genus fromPropithecus. The molars of the upper jaw are quadricuspidate, of the lower jaw five cusped. This genus has only eleven pairs of ribs instead of the twelve ofIndrisandPropithecus. The Avahis, unlike the Sifakas and Indrinas, lead a solitary life, or go about in pairs. They are, moreover, completely nocturnal.
The genusPropithecusis characterised by the fur being rather silky than woolly, which latter is the kind of fur found in the two other genera of the sub-family. They are also rather larger animals, the body reaching a length of nearly 2 feet. The tail is long as inAvahis; the inner incisors are larger than the outer. The "Sifakas," as these Lemurs are termed, have a reputation for gentleness of character, but, as is the case with other animals, the males fight for the possession of the females at the breeding season. They are mainly vegetarian in habit, and travel in large companies. There are at least three species, andseveral varieties are allowed. The colours of these Lemurs are bright, and distributed so as to form contrasting bands; thusP. coquereli, a variety ofP. verreauxi, has a black face and a body mainly white, with splashes of a rich maroon upon the limbs and upon the chest.
These Lemurs are diurnal, and are especially active in the early morning and evening, sleeping, or at any rate remaining quiet, during the heat of the day. Their fitness for an arboreal life is shown by the existence of a parachute-like fold of skin between the arms and the body, which suggests a commencement of the more complete parachute of Flying Foxes, etc. These Lemurs are said to be reverenced and therefore shielded from injury by the natives of Madagascar.
Sub-Fam. 2. Lemurinae.—The "True Lemurs" are all inhabitants of Madagascar and of the Comoro Islands. They have not such long hind-limbs as have the members of the last sub-family, nor are the toes webbed. The tooth formula differs from that of the Indrisinae in that there is one more premolar on each side of the upper jaw, and often one more incisor in the lower jaw, making thus a total of thirty-six teeth. Sometimes, however, the incisors of the upper jaw are totally wanting.
The Hattock, genusMixocebus, is a scarce creature, only known from a single species,M. caniceps. As it is rare, nothing is known of its habits. It has one pair of upper incisors. The creature is one foot and half an inch long, exclusive of the tail, which is an inch longer than the body.
GenusLepilemur.—The Lemurs belonging to this genus, entirely confined to Madagascar, as are all the Lemurinae, have received the perfectly unnecessary and pseudo-vernacular name of "Sportive Lemurs"; an equally inappropriate and not at all ingenious name of "Gentle Lemurs" being bestowed upon the allied genusHapalemur. InLepilemurthere are seven species, which are to be distinguished fromMixocebusin having the tail shorter than the body. There are no incisors in the upper jaw. The last molar is tricuspidate in the upper jaw; that of the lower jaw has five cusps. They are nocturnal creatures, and but little is known of their habits. Previously to Dr. Forsyth Major's visit to Madagascar only two species of the genus were known; he has added five others. The length of the body is 14 inches, and that of the tail 10 inches, inL. mustelinus, which is the largest species.
The genusHapalemur[403]has a shorter muzzle thanLemur, and shorter ears. There are two pairs of mammae instead of only one; these are upon the breast and abdomen. In the male there is a pair upon the shoulder. The incisors are small, sub-equal, and placed one behind the other; the last one is at the inside of the canines. The molars of the upper jaw and the last premolar have only three well-marked cusps; in the lower jaw they have four. The caecum is blunter and is not so long as inLemur; it differs from that of other Lemurinae in having only two supporting mesenteries, which are both furnished with blood-vessels. As inLepilemurand the Indrisinae the carpus has no os centrale.
The genus, which is confined to the island of Madagascar, has two species, of which one,H. simus, is the larger and has a broader muzzle, and does not possess the peculiar arm gland (Fig. 258) already described inH. griseus. The former species is stated by Mr. Shaw to be chiefly a grass-eater, and to dislike berries and fruits, which are usually so popular with Lemurs. It is, however, believed by some that there is but one species ofHapalemur.H. griseusis 15 inches long, and has a tail of the same length. Its native name is "Bokombouli." It is nocturnal, and is especially addicted to bamboos, upon the shoots of which it feeds and among which it lives. It is often exhibited in the Zoological Society's Gardens; but the specimens seem to be always males. This Lemur is of a dark iron-grey colour with a tinge of yellow, more marked in individuals which have received the separate specific name ofH. olivaceus.
The genusLemuris distinguished by the long tail, half as long as the body at the least, by the elongated face, and by the Fox-like muzzle; the teeth are present to the full number of the family, viz. thirty-six; the incisors are small and equal in size, and are separated from each other and from the canines by spaces. The molars of the upper jaw have five cusps, but there are only four in the lower jaw.
This genus is entirely confined to Madagascar and the Comoro Islands, and consists of several species, the exact number of which is doubtful. Wallace in hisGeographical Distributionallows fifteen; Dr. Forbes only eight, with a plentiful allowance of varieties. One of the best-known species isLemur catta, theRing-tailed Lemur, or the "Madagascar Cat" of sailors.Lemur macacoshows a remarkable sexual dimorphism, the male being black, and the female—formerly described as a distinct species,L. leucomystax—being reddish brown with white whiskers and ear tufts. This led to a confusion with a totally distinct species,L. rufipes, of which the male (regarded as distinct and calledL. nigerrimus) is entirely black. This latter identification is, however, considered by Dr. Forsyth Major[404]to be not quite certain at present.
The young Lemur is at least sometimes carried by the mother across her belly; its tail passes round her back and then round its own neck.
Fig. 259.
Fig.259.—Ruffed Lemur.Lemur varius.×1⁄9.
The Lemurs of this genus agree with those of some other genera in the loudness of their voice, which is constantly exercised. Some move about by day and others by night. They are insectivorous and carnivorous as well as vegetarian; and Mr. Lydekker suggests[405]that their abundance and hardiness is to be traced to this fondness for a mixed diet.Lemur cattaseems to be the only member of the genus that is not arboreal. It lives among rocks where but few trees, and those much stunted, occur. Many species ofLemurare always to be seen in the Zoological Society's Gardens. Fourteen "species" have at one time or another been exhibited.
Sub-Fam. 3. Galagininae.—This sub-family is found on the continent of Africa as well as in Madagascar; but the genera aredifferent in the two districts. In Madagascar we haveOpolemur,Microcebus, andChirogale; on the continent,Galago. The members of this sub-family have markedly large ears, which are but little furry; the tail is long. A very marked skeletal character distinguishes this sub-family from other Lemuridae, and allies them toTarsius, that is the lengthening of the calcaneum and naviculare in the ankle. The dental formula is as inLemur. The supporting bands of the caecum are in this sub-family as in the genusLemur. There are but two folds, of which one is median and non-vascular; the lateral fold bears a blood-vessel, and is joined by the median frenum. The brain is but little known. The only figure of the brain ofGalagois one by myself. There are four mammae, two on the breast and two upon the abdomen.
The genusGalagocomprises at any rate six distinct species. They are all African, and range right across the continent from Abyssinia as far south as Natal, and to Senegambia in the west. The incisors of the upper jaw are small and equal; there is a gap between the canine and the first premolar. The molars and the last premolar have four cusps; the last molar of the lower jaw has an additional fifth cusp as inMacacus, etc. The Galagos are chiefly nocturnal, and are more or less omnivorous. Owing to their long hind-legs these animals when they leave the trees advance upon the ground by hops like a Kangaroo.Galago senegalensismakes a nest in the fork of two branches, where it sleeps during the day. The Great Galago (G. crassicaudatus) is named by the Portuguese "Rat of the Cocoa-nut Palm." Sir John Kirk, after whom a variety of this species is called, relates that it is incapable of resisting the fascinations of palm wine, upon which it will readily intoxicate itself, and as a consequence brave probable captivity. I have referred above (p.536) to the patch of spines upon the tarsus ofG. garnetti.
The genusChirogaleis entirely confined to Madagascar. It is to be distinguished fromGalagoby the fact that the inner incisors are larger than the outer. There are five species of the genus known: four previously to Dr. Forsyth Major's recent visit to Madagascar, and a fifth brought back by him.[406]In connexion with this genus the naturalist just mentioned has observed that all the Lemurs of Madagascar, including the aberrantChiromys, differ from the African forms by the fact that the tympanic ring "is completely enclosed by the bulla ossea, but without osseous connexion with the same." This character he thinks so important as to justify the inclusion of all the Mascarene forms in one group as opposed to another group consisting of the continental Lemurs. In this eventChirogalewill have to be separated from its close association withGalago. For the present, however, it is left in the more generally accepted position.
Fig. 260.
Fig.260.—Smith's Dwarf Lemur.Microcebus smithii.× ¾.
Fig. 261.
Fig.261.—Mouse Lemur.Chirogale coquereli.× ½.
Microcebuscontains the most minute among the Lemurs.M. smithiihas a body only 5 inches long, the tail being another 6 inches. It occurs in Madagascar, and includes five species.
Opolemur, the Fat-tailed Lemur, was so called on account of adeposit of fat formed chiefly at the root of the tail, and intended to tide over the time of the creature's hibernation. But, as a matter of fact, this peculiarity also exists inChirogale. OfOpolemurbut two species are known, and of one of these, named after Mr. Thomas of the British Museum, only three examples are in existence in museums, that is to say in one museum—our own at South Kensington. Many of these dwarf Lemurs are exceedingly rare. In this genus and in the last two the palate has a pair of posterior fenestrae, of which there are also traces in other Lemurs, but which are particularly large inMicrocebus. This is, of course, a well-known character of the Marsupials, and also, which is more important in the present connexion, of certain Insectivores.
Sub-Fam. 4. Lorisinae.—This sub-family is the only one with a wide distribution, and it contains, with the exception ofTarsius, the only Asiatic members of the group. Correlated with its wide distribution there is more divergence in anatomical characters than is the case with the other sub-families of the Lemuridae. In external features all the three genera of this sub-family agree in their small size, their short or entirely deficient tail, large staring eyes, and the rudimentary character, or absence, of the index finger, which is never provided with a nail; in all of them the thumb diverges widely from the other fingers, and the great toe is so divergent as to be directed backwards. In the brain there is one character common to all three genera, and that is the small length of the angular fissure. The caecum, which is long, is supported by three folds, of which the median is anangious, and is sometimes attached to the longer of the two lateral folds, which are vascular. The members of this sub-family have more dorsal vertebrae than are found in other Lemurs; the range is from fourteen inLoris, to sixteen inNycticebus.
The genusNycticebuscontains only a single species,N. tardigradus, though four other names have been given to supposed varieties. Moreover, the genus itself has been namedStenops, as also the next genusLoris. The body of this animal is stouter than that of the next to be described. Professor Mivart has pointed out that, though Asiatic like the Loris, it presents more resemblances to the African Potto. The index finger is small; the inner of the two incisors is smaller than the outer, but both of one side are close together. They may be reduced to one on each side of the upper jaw.
Fig. 262.
Fig.262.—Slow Loris.Nycticebus tardigradus.× ⅓.
The animal has a wide distribution in the East, occurring in Assam and Burmah, the Malay Peninsula, Siam, and Cochin-China, Sumatra, Java, Borneo, and the Philippines. Its vernacular names signify "Bashful Cat" and "Bashful Monkey" in allusion to its nocturnal and shy habits. It lives among trees, which it does not voluntarily leave. Its movements are deliberate, as its popular name, Slow Loris, implies; but it makes up for this by a vigorous tenacity of grasp. The animals "make a curious chattering when angry, and when pleased at night they utter a short though tuneful whistle of one unvaried note, which is thought by Chinese sailors to presage wind." Much superstition has collected round this harmless though rather weird-looking creature. Its influence over human beings is as active when it is dead as when it is alive. "Thus," writes Mr. Stanley Flower,[407]"a Malay may commit a crime he did not premeditate, and then find that an enemy had buried a particular part of a loris under his threshold, which had, unknown to him, compelled him to act to his own disadvantage." The life of the Loris, adds Mr. Flower,"is not a happy one, for it is continually seeing ghosts; and that is why it hides its face in its hands!"
The genusPerodicticuscontains two quite recognisable species, known respectively as the Angwantibo and Bosman's Potto. The former has been regarded as referable to a distinct genus,Arctocebus. A curious internal character of the Potto which is visible, or at least can be felt, externally, is the long neural processes of the cervical vertebrae, which project beyond the level of the skin. The index finger is rudimentary and so is the tail, being only just visible (about an inch in length) in the Potto. The colour of both genera is a reddish grey, redder in the Potto. The incisors are equal and minute. Both species are confined in their range to West Africa, and are arboreal like the other members of the sub-family. The Potto seems to share the leisurely mode of progression of its Asiatic relatives, if Bosman, its original describer, is to be trusted. He says: "By the negroes called Potto, but known to us by the name of Sluggard, doubtless from its lazy, sluggish nature; a whole day being little enough for it to advance ten steps forward." The same writer did not at all appreciate his addition to zoological knowledge, for he remarked that the Potto "hath nothing very particular but his odious ugliness." The Angwantibo is rare and but little known. Our knowledge of its anatomy is derived from a paper by Huxley.[408]It is an animal measuring about 10½ inches in total length to the end of the tail, which is only a quarter of an inch long. The hands and feet are smaller than those ofPerodicticus. The index finger is rudimentary and has but two phalanges, and it has no trace of a nail. In this it agrees with the Potto, but "the spinous processes of the cervical vertebrae do not project in the manner described by van der Hoeven in the Potto, though they can be readily felt through the skin." The dental formula of this genus as of the last is I 2/2 C 1/1 Pm 3/3 M 3/3. The last lower molar has a fifth cusp, which is wanting in the Potto. The last upper molar is tricuspid. It is bicuspid in the Potto. It seems impossible to avoid agreeing with Professor Huxley that the Angwantibo is entitled to generic separation.
The genusLorisalso contains but a single species,L. gracilis, and is, as its name denotes, an animal of more slender build than the Slow Loris. Its eyes are very large, and the limbs excessivelyslender. The index finger is much as inNycticebus. The colour, too, is not widely different, being of a yellowish grey, but it lacks the dorsal stripe which distinguishes its relative. The incisor teeth are equal and very small. The last upper molar has four cusps instead of the three ofNycticebus. This Lemur is confined to Southern India and Ceylon, and has much the same habits as the last. But it is rather more active, and can capture small birds when sleeping upon the trees; its diet, however, is mixed, and is vegetarian as well as animal.
A mysterious Lemur, which we conveniently place as a kind of appendix to the present family on account of its locality, has been shortly described by Nachtrieb from the Philippines. The tail is rudimentary; there are two upper incisors, but as many as six lower. It is doubtful what the beast really is.
Fig. 263.
Fig.263.—Aye-aye.Chiromys madagascariensis.×1⁄10.
Fam. 2. Chiromyidae.—This family contains but a single genus and species, the Aye-aye,Chiromys madagascariensis, whose characters therefore are for the present those of the family as well as of the genus and species. The external features of this extraordinary animal will be gathered from an inspection of Fig. 263, from which it will be seen that the earlier name ofSciurusgiven to the creature was not by any means a misnomer. The Squirrel-like appearance is due, of course, chiefly to the strong and long incisor teeth. As to the external characters, which are of systematic importance,attention may be called to the long and bushy tail, to the greater length of the hind-limbs, to the abdominal teats (one pair) in the female, and above all to the singular third digit of the hand, which is thin and elongated. The thumb is, as in other Lemurs, opposable, and has a flat nail; the remaining digits have claws, as have also the toes with the exception of the great toe, which has a flat nail like the thumb.
The anatomy of this animal has occupied the attention of a considerable number of observers, dating from Sir R. Owen, who was the first to give a connected account of its entire organisation. The most recent paper of importance is by Dr. Oudemans.[409]The teeth are very unlike those of other Lemurs. The most remarkable divergence is in the incisors, which are present to the number of but a single pair in each jaw, and are shaped like those of the Rodentia, and in the same way as in that group grow from persistent pulps. There are likewise, as in the Rodents, no canines. There are two premolars in the upper jaw (none in the lower) and altogether twelve molars, so that there is a total of eighteen teeth. The intestine has a moderately long caecum. The brain has been most fully described by Oudemans, who had fresh material to work with, the brain described by Owen having been extracted from a spirit-preserved carcase. The angular fissure is well developed, as in Lemur and the Indri; but it does not join the infero-frontal. The antero-temporal fissure is also well developed.
"The name of Aye-aye," wrote Sonnerat, the discoverer of the animal, "which I have retained for it, is a cry of surprise of the inhabitants of Madagascar." It is, however, usually said that the animal itself makes a sound which may be written in the same way (or with an initial H). It is an arboreal and nocturnal animal, which accounts for its excessive rarity at one time. In one of his many eloquent essays upon natural history the late Mr. P. H. Gosse adduced the Aye-aye as an example of a creature on the verge of extinction. It is, however, now more frequently met with, though the superstition of the natives renders its capture a matter of some difficulty. There is a specimen at the moment of writing in the Zoological Society's Gardens. There has been some discussion as to the use of the slender middle finger: it is stated that it can thrust it into theborings of the larva of a certain beetle of which the Lemur is particularly fond, and can extract the insect, or at any rate discover its position, when it may be extracted by the powerful chisel-shaped teeth. The partiality of the Aye-aye for animal food of any kind including insects has been both reaffirmed and denied; and Mr. Bartlett has seen the creature use its slender finger for combing out its hair, and for other purposes of the "toilet." Dr. Oudemans has figured in his paper an apple which has been largely eaten by theChiromys; the fleshy pulp has been entirely excavated, leaving only the core and the skin, which are untouched. The Rev. Mr. Baron is one of the latest writers upon the ways of life ofChiromys.[410]He states that it inhabits the most dense parts of the forests. It has the habit of prowling about in pairs, and the female produces but a single young one at a birth. A nest, which is about 2 feet across, is made of twigs in lofty branches. This is occupied during the day, and entered by a hole in the side. With regard to the superstitious veneration in which the animal is held, it is said that if a person sleeps in the forest the Aye-aye will bring him a pillow. "If a pillow for the head, the person will become rich; if for the feet, he will shortly succumb to the creature's fatal power, or at least will become bewitched." But a counter-charm may be obtained. It is said that the reverence for this beast leads the natives to bury carefully a specimen found dead.
Fam. 3. Tarsiidae.—This family also consists of but a single genus,Tarsius, to which it is the general opinion that but a single species belongs; there are, however, at least four different specific names on record. The general aspect of the animal is not unlike that of a Galago, with which it also agrees in the elongation of the ankle; but the elongation is more pronounced in the present genus. The ears are large, and the eyes are extraordinarily developed. The fingers and toes terminate in large expanded discs, and are furnished with flattened nails except on the second and third toes, which have claws. The tail is longer than the body and is tufted at the end. The skull is more like that of the Anthropoidea than is the skull of any other Lemur. The resemblance is by reason of the almost complete separation of the orbit and the temporal fossa by bone;there is, however, a gap left to mark the Lemurine characters of the animal. The placenta, too, has been compared to that of the Apes. The dental formula is that of the genusLemur, save for the absence of an incisor on each side of the lower jaw; the number of teeth is therefore thirty-four. The incisors of the lower jaw are upright, and not procumbent as in other Lemurs. The caecum is of moderate length. The brain is almost smooth, but there is a Sylvian fissure and an antero-temporal, which latter does not reach the lower margin of the brain, but divides the middle part of the temporal lobe. The name Tarsier, as may be inferred, was originally given to this creature by Buffon on account of the abnormal ankle, and it was compared by him with the Jerboa, like which animal the Tarsier leaps when it descends to the ground. The genus is Malayan, but its range extends to the Philippines and to Celebes and Borneo. The Tarsiers are nocturnal and particularly arboreal; they live in pairs, in holes in tree stems, and are mainly insectivorous in their food. One, rarely two young are produced at a birth. Contrary to what is found in many Lemurs, the Tarsier is a silent creature, and at most emits a "sharp, shrill call." Dr. Charles Hose, who has studied this creature, has noticed that the mother often carries her young one about in her mouth like a Cat. Like so many Lemurs this animal is held in superstitious dread, which no doubt is the result of its most weird appearance.[411]
Fig. 264.
Fig.264.—Right pes ofTarsius spectrum. (Nat. size.)a, Astragalus;c, calcaneum;c1, internal cuneiform;c2, middle cuneiform;c3, external cuneiform;cb, cuboid;n, navicular;I-V, the digits. (From Flower'sOsteology.)
Fossil Lemurs.—The Lemuroids are a very ancient race; they extend back to the very earliest strata of the Eocene, the Torrejon and Puerco beds, which, as already said, are thought to be more referable to the Cretaceous than to the Tertiary epoch.One of these early forms is referred to the genusMixodectes, a genus which has been placed, though with a query, in the order Rodentia. It appears, however, to be a Lemuroid, and is of American range. The incisor teeth have been held to argue that it lies on the direct track ofChiromys; but other features, more especially the form of the astragalus, have been used to argue the justice of the inclusion of this type within the order Rodentia. Allied, as it is supposed, to this form isIndrodon, also of the lowest Eocene deposits of the United States.Indrodon malarisis known from fragments of nearly all parts of the skeleton. They indicate the existence of a creature of about one-half the size ofLemur varius. It had slender limbs and a long and powerful tail. The humerus, as in so many archaic beasts, has an entepicondylar foramen. The femur has three trochanters, and the fibula articulates with the astragalus. It is not always easy to distinguish these primitive mammals from each other, so that the minutest of characters have to be called in to our assistance. One of the contemporaneous groups with which these early Lemurs might be confused is that of the Condylarthra; it is important, therefore, to note that inIndrodonthe calcaneo-cuboidal articulation is nearly flat, and not bent as it is in the former group. The teeth are of the tritubercular pattern. The incisors are not known, but the molars and premolars are each three. To the same family, which has been termedAnaptomorphidae, is referred the genusAnaptomorphus, which has been specially compared toTarsius. This small animal has a Lemurine face with huge orbits. It has a premolar less thanIndrodon. It has been ascertained thatA. homunculushad an external lachrymal foramen.[412]
Another family, that of theChriacidae, appear to hover on the border line of Lemurs and Creodonts, having been referred to both by various palaeontologists. Professor Scott suggests their Lemurine or at least Primate relationships, while Cope urged their Creodont affinities. A difficulty raised by Scott was, that inChriacusthe premolars of the lower jaw were spaced. But it appears that this is not fatal to their inclusion in the Primates, sinceTomitherium, an "undoubted Primate," shows the same feature. IfChriacusis a Lemur it is an earlier type than thosewhich have been considered; for it has the typical Eutherian dentition of four premolars and three molars. These teeth, especially the superior molars, are particularly compared to the corresponding teeth ofLemurandGalago. Of this and the allied genus,Protochriacus, several species are known.
Adapis, a representative of another family, is one of the best known of ancient Lemuroids. It has the typical mammalian dentition of forty-four teeth in a close series without diastemata. The orbits are completely separated from the temporal cavity, the eyes looking forwards. The canines are large and caniniform. The skull is deeply ridged behind with the usual sagittal crest. This genus is European, and corresponds to the already mentioned American EoceneTomitherium, perhaps belonging to the same family.
Nesopithecusis an extinct genus from Madagascar, lately described by Dr. Forsyth Major.[413]There are two species,N. robertiandN. australis. The dental formula is I 2, C 1, Pm 3, M 3, for the upper jaw, the lower jaw having but a single pair of incisors. The lachrymal foramen is just inside, or on the edge, of the orbit, so that one distinctive Lemurine character is lost. The genus is also Ape-like in the form of the canines and incisors, these having been especially compared by Dr. Forsyth Major with those of the Cercopithecidae. The molars, too, agree with those of the same family. There is, however, one important feature in whichNesopithecusresembles not only the Lemurs as opposed to the Apes, but the Malagasy Lemurs. As already mentioned (p.544), Dr. Major has shown that in the Malagasy Lemurs, even including the aberrantChiromys, and in the Tertiary and EuropeanAdapis, the bulla tympani is not produced by an ossified extension of the annulus tympanicus, but from the adjacent periotic bone, the annulus remaining separate and lying within the fully-formed bulla. This feature shows conclusively thatAdapisis a Lemur, and thatNesopithecus, originally supposed to be a Monkey, cannot be removed from the Lemuroidea, many though its likenesses to the higher Primates undoubtedly are. However, this feature, combined with the fact that the orbital and temporal cavities are in communication, shows the Lemuroid position ofNesopithecus, though it is quite conceivable that it is on the way to become an Ape.
A family,Megaladapididae, has been quite lately founded by Dr. Forsyth Major[414]to include the remains of a gigantic extinct Lemur from Madagascar, which when alive, so far as we can judge from the skull, must have been three or four times the size of the Common Cat. The nameMegaladapis madagascariensiswas given to the fossil on account of certain resemblances to the also extinctAdapis. It differs from other Lemurs in a number of characters which jointly warrant its inclusion in a distinct family. The small size of the orbits suggest a diurnal life; the deep mandibles, which, unlike what is found in other Lemurs, are completely blended at the suture, point to the existence of a howling apparatus, as inMycetes. The low brain-case is a character which is found in so many extinct Mammalia belonging to many different orders that it weighs neither one way nor the other in considering the systematic position of the animal. The shape of the molars, which are three in each half of each jaw as in other Lemurs, is, according to the discoverer, like that of the genusLepilemur. The incisors and the canines are not known. Of a still larger form,M. insignis, the molar teeth are known.[415]
The Apes differ from the Lemurs in that the teats are always restricted to the thoracic region; the orbit, though surrounded by bone as in the Lemurs (and inTupaia, a very Lemur-like Insectivore), does not open freely behind into the temporal fossa as in Lemurs (exceptTarsius). The lachrymal opening is inside the orbit instead of outside; the cerebral hemispheres are more highly developed, and conceal, or nearly conceal, the cerebellum; the upper incisors are in close contact; a few other points are mentioned under the description of the characters of the Lemurs. There are altogether about 212 species of Monkeys and Apes. They are tropical and subtropical in range, and, with but few exceptions, are impatient of cold.
The Monkeys are primarily divisible into two great divisions, which have been termed, on account of the characters of the nose,the Catarrhines and Platyrrhines. In the former the nostrils look downward and are close together; in the latter they are separated by a broad cartilaginous septum, and the apertures are directed outwards. But numerous other points of difference separate these two groups of the Monkey tribe. The Catarrhines often have those remarkable ischial callosities, patches of hard skin brightly coloured; the tail may be totally wanting as a distinct organ, as is the case, for instance, with the Anthropoid Apes; there are often cheek pouches, so that, as Mr. Lydekker has remarked, if a Monkey be observed to stow nuts away in its cheeks for future reference, we may be certain that its home is in the Old World, for the Catarrhines are exclusively denizens of the Old World, while the Platyrrhines are as exclusively New World in range. Again, those of the Catarrhines which do possess a long tail, such as the members of the genusCercocebus, never show the least sign of prehensility in that tail. The teeth of the Catarrhines are invariably thirty-two in number, the formula being I 2/2 C 1/1 Pm 2/2 M 3/3 = 32.
In the Old-World Apes there is a bony external auditory meatus, which is wanting (as a bony structure) in the Platyrrhines. The late Mr. W. A. Forbes pointed out that in most of the New-World forms the parietals and the malars come into contact; in the Monkeys of the Old World they are hindered from coming into contact by the frontals and the alisphenoids. The Platyrrhines may have the same number of teeth; this is the case with the Marmosets, but in them there are three premolars and two molars; in the remaining New-World Monkeys there are thirty-six teeth, but of these three are premolars and three molars.
Not only are these two groups of the Primates absolutely distinct at the present day, but they have been, so far as we know, for a very long time, since no fossil remains of Monkeys at all intermediate have been so far discovered. This has led to the suggestion that the Monkeys are what is termed diphyletic,i.e.that they have originated from two separate stocks of ancestors. It is hard, however, to understand on this view the very great similarities which underlie the divergences that have just been mentioned. But, on the other hand, it is equally hard to understand how it is that, having been separated from each other for so long a period, they have not diverged further instructure than they have. The Platyrrhines seem to stand at the base of the series. This is another example of the existence of archaic creatures in South America.
Fam. 1. Hapalidae.—We may begin the account of the Platyrrhine Monkeys with the Hapalidae or Marmosets; for this family is structurally lower than the rest. They have thirty-two teeth, arranged as in the following formula: I 2/2 C 1/1 Pm 3/3 M 2/2 = 32. The molars have three main tubercles, and not four as in the higher forms. The digits are for the most part clawed, not nailed, as in the higher types; the great toe alone bears a flat nail. The tail, too, is ringed, a condition which is characteristic of many of the lower groups of mammals, but not of the higher Apes. The cerebral hemispheres are smooth, but this is a matter rather connected with their small size than with low zoological position. The tails of the Marmosets, unlike those of so many other American Monkeys, are not prehensile though they are long.
The genusHapaleis broadly distinguished from the other genus,Midas, by the fact that the lower incisors slant forwards as in the Lemurs. They are small, soft-furred, long-tailed Monkeys, familiar to every one. There are some seven species, which are entirely restricted in range to Brazil, Bolivia, and Colombia, one species only,H. pygmaea, extending northward into Mexico.
Of Tamarins, genusMidas, there are rather more species—about fourteen. They are South and Central American in distribution. Since both these genera are arboreal in habit, it is extraordinary that they have not the prehensile tails of their American allies. As, however, the late Mr. Bates observed an individual of the speciesM. nigricollisfall head-foremost from a height of at least 50 feet, alight on its feet, and run off as if nothing in particular had occurred, it is evident that no extra prehensile powers are absolutely necessary. Some of the Tamarins have a long mane; this is well seen inM. rosalia, or rather inM. leoninus, which, if not identical with it, is at least very closely allied to it. The name is obviously derived from the characterreferred to, and the Monkey, originally described by the traveller von Humboldt, is said to have "the appearance of a diminutive lion."M. bicoloris an example of the species with no mane, but with a patch of white round the mouth, looking like "a ball of snow-white cotton" held in the teeth.
Fam. 2. Cebidae.—The remaining American Monkeys are comprised in the family Cebidae. This is to be distinguished from the last by the fact that there is an additional molar, thus making thirty-six teeth in all. The tail, sometimes very short, is more generally long and highly prehensile, being nude at the extremity, which part is therefore especially prehensile; this state of affairs is often to be seen in animals with prehensile tails. The Cebidae, though for the most part larger than the Marmosets, never approach in size the Old-World Apes.
Typical of the family is the genusCebus, including the "Capuchin" Monkeys, and consisting of nearly twenty species; the tail, though prehensile, is covered with hair to the tip, a fact which is indicative of a less perfect prehensility than is exhibited in some Monkeys with a naked under surface to the tip of the tail. The thumb is well developed. The genus ranges from Costa Rica to Paraguay. The commonest Monkey which accompanies the street organs of this country is aCebus. It is a popular delusion that these and other monkeys are purely vegetable-feeding animals.Cebusis in fact particularly fond of caterpillars, as are also the Marmosets.
Allied toCebusisLagothrix, the Woolly Monkey, of whichL. humboldtiis the best-known species, there being indeed but one other. It is a larger and heavier animal than any species ofCebus; and the Hare-like woolliness of the fur suggested its scientific name to its original describer, von Humboldt. It has a perfectly prehensile tail, naked at the tip. The thumb and great toe are well developed. These are purely fruit-eating Monkeys, and are known as "Barrigudos" by the Portuguese of the Amazon country on account of their prominent belly, due apparently to the immense amount of fruit consumed. They are, or were, much eaten by natives.
Brachytelesis a little-known genus, connecting the last with the next genus. The under fur is woolly; the thumb is small or absent. The tail is naked below.
The Spider monkeys,Atelesor Coaitas, have been described asthe most typically arboreal of American monkeys. The use of the prehensile tail can frequently be studied in living examples in the Zoological Society's Gardens. With this "fifth hand" the Monkey feels for a place to grasp, and securely twists its tail round, moving it with the greatest ease from point to point. When the tail is being thus used it is carried erect over the head. The fact that this genus possesses no functional thumb is thought to be associated with the extreme perfection of its adaptability to an exclusively arboreal life. The hand without a thumb can act as an equally efficient hook for suspending the body; and what is useless in nature tends to disappear. These Monkeys have a wide range, extending from Mexico in the north to Uruguay in the south. There are ten species. The flesh of many Monkeys is eaten not only by natives but by Europeans; but the Spider Monkeys are said to furnish the most sapid food of all.