CHAPTER XVI.

[561]Foss. South D. tab. xxxiii. p. 228.[562]American Phil. Trans, vol. iii. new series, pl. xvi. on the Saurodon, by Dr. Hays; and Journal Acad. Sciences, Philadelphia, vol. iii. on theSaurocephalus, by Dr. Harlan.

[561]Foss. South D. tab. xxxiii. p. 228.

[562]American Phil. Trans, vol. iii. new series, pl. xvi. on the Saurodon, by Dr. Hays; and Journal Acad. Sciences, Philadelphia, vol. iii. on theSaurocephalus, by Dr. Harlan.

Lign. 204. Fossil Teeth and Jaws of Fishes.Chalk.Sussex.Fig.1.—Tooth ofSaurocephalus lanciformis.Lewes.2.—Teeth ofSaurocephalus striatus.Brighton.Portion of the jaw, with five teeth.3.—Fragment of a jaw, with two perfect teeth, and the base of another, ofSaurodon Leanus.Kemptown, Brighton.4.—Enchodus halocyon.Left branch of the lower jaw, with teeth; and one front tooth of the opposite portion.Lewes.

M. Agassiz retains the names imposed by the American naturalists, and has placed these genera in the family of Scomberoids (Mackerel,Swordfish). They belong to thePharyngognathiof Muller. The teeth are disposed in a single row, and fixed in deep sockets by a simple root, or fang, which is frequently somewhat excavated by the pressure of a successional tooth. InSaurodon Leanusthe crown of the tooth is angular, and barbed, and supported on a sub-cylindrical shank, or stem (seeLign.204,fig.3). The microscopical structure of these teeth presents that peculiar reticulated disposition of the medullary canals throughoutthe entire body of the tooth, which is only found in the dental organs of fishes.

Hypsodon Lewesiensis.(Foss. South D.tab. xlii.)—The Sussex and Kentish Chalk also contain the remains of a very large fish, belonging to the Pharyngognathi, with extremely upright, long, conical, compressed, pointed teeth, which, like those of the Saurodon, are implanted in sockets. These teeth are commonly of a delicate fawn colour externally and of a dark brown internally; having a large simple pulp-cavity. InFoss. South D.(tab. xlii.) are represented portions of an intermaxillary and jaw-bone with teeth; a vertebra, deeply biconcave; and a large bone, apparently a branch of theos hyoides; all found in the same block of chalk.[563]

[563]A magnificent specimen (now in the British Museum) displays, on the same slab of chalk, a large portion of the cranium, teeth, several vertebræ, ribs, and many other bones, belonging to a fish of considerable magnitude.Petrif.p. 444.

Enchodus(sword-tooth)halocyon.Lign.204,fig.4. (Poiss. Foss. tom. v. tab. xxvc.)—The specimen figured is a portion of the lower jaw, with one row of elongated, conical, slightly curved, pointed teeth; the two anterior teeth being much longer and larger than the others; it affords a good illustration of the dental organs ofEnchodus; a genus of Acanthopterygian fishes, the jaws and teeth of which are often found in the Sussex Chalk. The teeth are of various sizes, and attached by anchylosis, one row on the premandibular bone, and another irregular row of smaller teeth to the inside of the lower jaw. The two anterior teeth are very large, and of a peculiar form: their base is wide and solid, and the shank of the tooth is suddenly contracted immediately above, and becomes elongated into a point. These teeth are generally of a dark colour, have a glossy aspect, and are very brittle; differing so remarkably in this respect from the shark’s teeth, with which they are usually collocated, that mere fragments can be readily identified. Theexternal surface of the lower jaw is marked with finely granulated, longitudinal ridges or striæ.[564]

[564]A fine example of the lower jaw, with twelve teeth, is figuredFoss. South D.tab. xli. and another, with the upper jaw and teeth,Geol. S. E.p. 140. Beautiful figures of the remains of Saurocephalus, Enchodus, Hypsodon, and many other fine Chalk fishes, are given in Dixon’sFossils of Sussex, 4to. 1850.

Mr. Toulmin Smith, of Highgate, has in his Museum a portion of the lower jaw with fifteen teeth of a small individual, imbedded in the centre of a flint nodule, from Gravesend, which was discovered by accidentally breaking the stone. The bone of the jaw and the teeth are of a dead white colour, and appear not to be in the slightest degree silicified; but in those teeth which are broken the pulp-cavity is filled with quartz, which must have transuded through the walls of the teeth.

Ichthyolites of recent species.—The distinguished naturalist to whose labours in fossil Ichthyology we have been so largely indebted, states, that of the many hundred species submitted to his notice, but one can be identified with any fish now living. This conclusion must, however, be received with some reservation; for, among the fossil genera, founded on the teeth, there are species which certainly cannot be distinguished from recent forms. And in the diluvial drift at Breslau, associated with the bones of the fossil elephant (Elephas primigenius), the remains of a pike, closely resembling the common European species, have lately been discovered.[565]

[565]Agassiz,Poiss. Foss.tom. v. p. 68.

The exception above alluded to, is a little Malacopterygian fish, rather larger than a Sprat, called the Capelan (Mallotus villosus), which inhabits the banks of Newfoundland, and other parts of the coasts of the northern seas. Fossil specimens of this fish.[566]occur in nodules of induratedmarl or clay, on the coast of Greenland.[567]It is supposed that these Ichthyolites are of very recent date: and that similar fossils are in the progress of formation.

[566]SeePoiss. Foss.tom. v. pl. lx., in which the skeleton of the recent fish, and specimens of the fossil species, are represented.[567]Similar fossils have been obtained from the "Drift" on the Saco River, thirty miles north of Portsmouth, New Hampshire. See Lyell’s Second Visit to the United States, vol. i. p. 29.

[566]SeePoiss. Foss.tom. v. pl. lx., in which the skeleton of the recent fish, and specimens of the fossil species, are represented.

[567]Similar fossils have been obtained from the "Drift" on the Saco River, thirty miles north of Portsmouth, New Hampshire. See Lyell’s Second Visit to the United States, vol. i. p. 29.

Ichthyopatolites, or imprints of the pectoral fin-rays of certain fishes. Under this name Dr. Buckland described certain problematical markings observed on a flag-stone from a coal-pit at Mostyn, in Flintshire, and now in the Geological Society’s Museum. It consists of curvilinear scratches or imprints, disposed symmetrically at regular intervals on each side a smooth level space, about two inches wide, which may correspond to the body of a fish, the pectoral fins of which Dr. Buckland suggests were the instruments by which the markings in question were formed.

These scratches follow each other in nearly equidistant rows of three in a row, and at intervals of about two inches from the point of each individual scratch to the points of those next succeeding and preceding it; they are slightly convex outwards, three on each side the median space, or supposed track of the body of the fish. Dr. Buckland, in the memoir referred to, shows that these markings cannot be referable to the imprint of the feet or claws of reptiles, and points out the structure of the bony anterior rays of the pectoral fins, as in certain Siluroid and Lophoid fishes, and in the Climbing Perch (Anabas scandens), or theHassar(Doras costata), and refers also to the ambulatory movements of the common Gurnard, in corroboration of this opinion.[568]

[568]Proceedings of Geol. Society, vol. iv. p. 204.

Geological Distribution of Fossil Fishes.—From the incidental notices of the geological habitats of the fossil fishes enumerated in our survey of this class of beings, thereader cannot fail to have remarked, that the most recent strata abounded in forms related to the inhabitants of the existing seas and rivers; while the most ancient teemed with species and genera of families altogether extinct, or of prodigious rarity in the recent fauna.

In general terms, it may be stated, upon the authority of M. Agassiz, that the Ichthyolites of the Tertiary deposits approach in their characters to the living genera, but all the species are extinct. The newer Tertiary, as the Crag, contain genera common to tropical seas, as the large sharks (Carcharias), and eagle-rays (Myliobates), &c. In the Eocene, or most ancient Tertiary, as the London and Paris basins, Monte Bolca, &c., many of the Ichthyolites are closely related to recent genera. Of the Chalk fishes, a few only are of recent genera, but the majority are still allied to Tertiary forms. In the Chalk, thePharyngognathi,Acanthopteri, andMalacopteriare met with as new types; and indications of theHybodontidæ,Sauroidei, andCœlacanthi(the last derived from the Devonian, and the other two from the Carboniferous Limestone) appear for the last time.

The ichthyic fauna of the Cretaceous deposits is closely related by the majority of itsfamilygroups with that of the series of strata from the Lias to the Wealden, inclusive. In and above the Lias all the ganoid fishes arehomocercal. Below the Lias, the genera and species are far more removed from existing types, and almost all areheterocercal.

Of the eight thousand living fishes known to naturalists, three-fourths belong to the Cycloid and Ctenoid orders, and of these no species are known below the Chalk; the other fourth is referable to the Placoids and Ganoids, of which there are comparatively but few existing species. Yet fishes of these two orders almost solely flourished during the ancient Secondary formations; for below the Lias, the predominant recent orders are altogether absent.Beneath the Coal, true carnivorous fishes, with trenchant teeth, are almost unknown; but omnivorous species, with either brush or obtusely conical teeth, and great sauroid fishes, are the prevailing representatives of the class.[569]In fine, the Ichthyolites of the different formations constitute two grand groups, which have their boundary line at the base of the Cretaceous deposits. The first and most ancient comprises the Ganoids and Placoids; the second, more intimately related to existing types, comprehends forms more diversified; these are principally Ctenoid and Cycloid, with a small number of the two preceding orders, which insensibly disappear; and their few living analogues are very distinct from the ancient species. Now, although deductions of this nature may require to be modified with the progress of knowledge, yet the generalizations thus obtained are founded on so vast an accumulation of facts and observations, as to render it improbable that they will be materially invalidated by future discoveries; for they remarkably accord with the results derived from the investigation of the fossil remains of all the other classes of animals. The most modern deposits contain the remains of animals allied to the existing species; the most ancient, of forms altogether extinct, or of excessive rarity in the recent faunas. The discovery of existing species, or genera, in the most ancient strata, would modify, but not destroy, the inferences deduced from the facts hitherto obtained; and every geologist is prepared to find that such may be the case.

[569]In the several chapters on the different formations, as arranged in theWonders, the student will find succinct notices of the distribution of thegeneraof fishes throughout the fossiliferous deposits. A list of the Chalk species known in 1848 is given at pp. 356-359,Wond.

Thus of the Sharks, with triangular notched teeth, which are so common in the Tertiary formations, and were formerlyunknown in the ancient Secondary, one representative has been found in the Carboniferous system (seep. 595). But, if teeth of this type should hereafter be discovered in every Secondary deposit, the great preponderance of these fishes over the Sauroid in the Tertiary, and in the existing seas, would not be the less remarkable.

On Collecting and Developing Fossil Fishes.—From what has been advanced, the reader will have obtained a general knowledge of the fossil remains of this class that are likely to be met with in particular deposits. Thus, he will expect to find the teeth of large sharks and rays in the Tertiary clays and sands; and skeletons and perfect specimens of numerous Ctenoid and Cycloid fishes in the laminated marls and fine limestones of the same formations. In the Chalk, with numerous teeth of sharks, he may discover splendid examples of Cycloid and Ctenoid fishes; and, in the Wealden, large Ganoidian forms. Passing to the ancient Secondary strata, the extraordinary buckler-headed and Sauroid fishes will arrest his attention; and their vestiges will be found, more or less perfect, in the shales and limestones, and in the indurated nodules of clay and sandstone.

The detached teeth of fishes in Tertiary sands and clays may be easily obtained entire, and should be arranged in the same manner as the shells (seep. 442), either in trays, or on boards. The triangular teeth, with lateral denticles, must be carefully extracted, so as to preserve those appendages on which the specific and generic distinctions of many Ichthyolites depend. M. Agassiz particularly recommends the preservation of all the specimens collected together in the same locality, as many may probably belong to the same individual, and thus the dental organization of theoriginal be determined. Teeth collected from the same stratum in different places, should not, therefore, be mixed together. Several series of the same kind of teeth should be preserved, and as many as possible of each kind; for specimens apparently identical may prove to be highly instructive as a series. I have often had occasion to regret the disposal of supposed duplicates, in my earlier researches, which would have tended to elucidate the characters of those specimens which were retained.

The Ichthyolites, and their detached teeth and fins, in the Chalk and other soft limestones, may be cleared by means of a penknife or graver and small sharp chisels. It is preferable to leave the teeth attached to small blocks of the chalk; as in the examples, figuredLign.193. But to develop the beautiful Chalk Ichthyolites, particularly those of the Osmeroides, Macropoma, &c. some practice and considerable dexterity are required. The compressed fishes, as the Beryx, like those in the Tertiary limestones, often lie in the sedimentary plane of the stone, and may be sufficiently exposed, by a blow of a hammer or a pick, to show the nature of the fossil, and admit of being easily developed. But the fishes with sub-cylindrical bodies very commonly split asunder in a transverse direction: and those with spinous scales, as the Macropoma, adhere so firmly to the chalk, that, to display the external surface of their scales, the surrounding stone must be removed piecemeal, in the manner described for the Chalk crustaceans (seep. 544). The collector who sees the splendid Chalk fishes in the British Museum,[570]and learns that they were found in the Chalk of Kent and Sussex, will be grievously disappointed, upon visiting the quarries from which they were obtained, if he expects to discover specimens with any considerable portion of the scales, or body, exposed. It was many years before the quarry-men acquired the tact they now possess, ofdetecting, from very slight evidence, the presence of an Ichthyolite in a block of chalk: patches of scales, which the quarry-men called "bran," and detached sharks’ teeth, "birds beaks," and "snakes' tongues," and teeth of Ptychodus, "slugs," being the only remains of fishes generally observed and laid aside by the workmen.

[570]Petrifactions, pp. 441, 444.

The fossilSalmonorSmelt(seep. 626), which may be considered as one of the most extraordinary of the Chalk fishes found in England, affords an excellent illustration of the mode of developing the Ichthyolites of this formation. This interesting fossil is delineated on a small scale, in three different states, inPlate II.; and affords a good practical lesson for the young collector. Among some blocks of chalk which a recent fall in one of the quarries near Lewes had brought to light, was a large mass split asunder, and exposing on each corresponding surface an irregular oval marking of a yellowish brown colour; this appearance is representedPl. II. fig. 1. Presuming that these markings were produced by a transverse section of the body of a fish, the two blocks were trimmed into a portable size, and accurately cemented together with veryhot, thin, freshglue. When consolidated, some of the chalk was chiselled off in the supposed longitudinal direction of the enclosed fish, and part of the body, covered with scales, was exposed, asPl. II. fig. 2. With the view of ascertaining the extent of the Ichthyolite, some of the surrounding stone was then removed towards each extremity of the block, and traces of the fish were discovered, as shown in the same figure. The task of completely developing the fossil was thus rendered comparatively easy; the chalk was chiselled, cut, and scraped away, till the perfect fish, as seen infig.3, was developed.[571]The block was then reduced to a convenient size,and the edges sawn smooth. The chalk is easily cut with a carpenter’s saw; the instrument should be short and strong, and the teeth of moderate size.

[571]The figure inPl. II.is too small to convey an accurate idea of this Ichthyolite, which is now in the British Museum; seePetrifactions, pp. 445, 446. M. Agassiz’s figure very inaccurately represents the original. A beautiful lithograph of this fish, by Mr. Pollard, of Brighton, was published in the Catalogue of the Mantellian Museum, 1836.

When aportionof the body of an Ichthyolite of this kind is found in a block of chalk, and the fracture of the block appears to be recent, diligent search should be made for the corresponding piece; for it may probably be found to contain the other part of the fish. A splendid specimen ofOsmeroides Lewesiensis, more than a foot long, was thus obtained. The quarry-men, in a block of chalk which a recent fall had thrown down, discovered a few inches of the caudal portion of the body of a fish; on the broken surface of the stone, a section of the body was distinctly seen, as in the specimen previously described. Search was made among the fallen masses for the corresponding piece, but without success. Upon observing the face of the quarry exposed by the recent fall, on a projecting block, many yards above our reach, a discoloured spot was indistinctly seen, and it was conjectured that this might prove to be the other moiety of the Ichthyolite. The workmen were directed to preserve this block if possible; but it remainedin situseveral months, and until the rock was again blasted; when the stone so long coveted rolled away from the fallen mass, and fortunately was soon discovered. It proved to be the corresponding portion of the fish; with the head, opercula, branchial arches, pectoral fins, and the anterior part of the body covered with beautiful cycloid scales. In the preparation of fossils of this kind, glue as the cement, and a paste made of plaster of Paris with thin glue, to fill up the crevices and strengthen the block, are the materials I have employed. The fossil remains of fishes in other rocks require to be extracted and developed in the manner previouslydirected for the Echinoderms, Cephalopoda, &c. (pp.332,497.)

The collector may be reminded, thatOtolithes, or ear-stones (p. 574), are found in the Crag of Norfolk, and other Tertiary strata; and that Coprolites, associated with minute scales, bones, &c. of small fishes, constitute, in some localities, layers of considerable thickness and of great extent. The "bone-bed" of the Lias, near Westbury, and that of the Ludlow series on the banks of the Teme, near Ludlow,[572]are well-known examples of such a deposit.

[572]See Mr. Strickland’s interesting notice of the distribution and contents of this "bone-bed," in the Quart. Geol. Journ. vol. ix. p. 8

Microscopical Examination.—A few words on the microscopical examination of the remains of fishes may be useful. The structure of the large, and the forms of the minute scales, may be seen by a common lens, and without preparing the specimens. But for the examination of the intimate organization of scales, teeth, &c. the microscope is required; and the method directed for the investigation of flint (p. 373) should be employed. The scales, portions of the membranes of the air-bladder, stomach, &c. and thin chips of the teeth, rendered temporarily transparent by oil of turpentine, or permanently so by Canada balsam, should be viewed by transmitted light. But the intricate structure of the dental organs, the medullary canals, and the calcigerous tubes, cannot be successfully investigated without the aid of the lapidary, or the adoption of the process described at page 67 for the preparation of fossil wood for microscopical examination.

BRITISH LOCALITIES OF FOSSIL FISHES.

⁂ The detached teeth, scales, vertebræ, &c. of fishes are so extensively distributed, that there is scarcely a cliff or quarry of fossiliferous rock in Great Britain, that does not contain some examples. The following list of localities must, therefore, be regarded as merely directing the student to a few places, in which particular fossils of this class have been discovered.

Abergavenny.Mt. L.Teeth ofPsammodus,Orodus, &c.

Armagh, Ireland.Mt. L.Numerous teeth and spines.

Arundel, Sussex.Cret.Quarries in the neighbourhood; beautiful Chalk fishes.

Aust Cliff, near Westbury, Somersetshire.Lower Lias.Pholidophorus, &c.Base of Lias.In a layer called the bone-bed, containing bones, scales, teeth, and Coprolites of fishes. Teeth ofCeratodus, &c.

Axmouth.Base of Lias: Bone-bed.Numerous scales, bones, and teeth.Saurichthys, &c.

Barrow-on-Soar.Lias.Dapedius.

Bracklesham Bay, Sussex.Eocene.Magnificent specimens of Rays, asMyliobatis,Aëtobatis, and ofChimæroidswere collected by the late F. Dixon, Esq., and are now in the British Museum.

Brighton. Cret. Chalk quarries in the vicinity.Beryx,Dercetis,Saurocephalus,Saurodon, and the common species of teeth, &c.

Bristol.Mt. L.The usual species ofPsammodus,Orodus,Onchus, &c.

Burdie-house, near Edinburgh.Carb.Palæoniscus,Megalichthys,Holoptychius, &c.

Caithness, Scotland.Old Red.Dipterus, &c.

Charing, Kent. Many fishes in the Chalk.

Chatham, Kent.Cret.Beryx,Hypsodon, and the usual teeth, &c.

Cheltenham.Base of Lias.In the bone-bed teeth, scales, Coprolites.

Clayton, Sussex.Lower Chalk.Beryx microcephalus, and other rare Ichthyolites.

Clifton, near Bristol.Mt. L.Psammodus,Orodus, &c.

Cromarty, Scotland.Old Red.Coccosteus,Pterichthys, &c.

Cuckfield, Sussex.Wealden.Lepidotus, Hybodus, Acrodus.

Cullercoats, Durham.Permian.Palæoniscus, &c.

Dinton, Vale of Wardour.Purbeck.Leptolepis,Ceramurus, &c.

Downton Hall, near Ludlow.Devonian.Cephalaspis,Dipterus, &c.U. Sil.In a quarry on the banks of the Teme, a fish-bed composed of scales, teeth, and Coprolites, in Upper Ludlow limestone.

Dudley.Sil.Ichthyodorulites.

Dungannon, Ireland.Permian.Quarry at Rhone-hill; numerous smallPalæonisci,P. catopterus.

East Thickley, Durham.Magnesian Limestone.Palæonisci.

Glammis, Forfarshire.Devon.Cephalaspis, Gyrolepis, Dipterus.

Gravesend and Northfleet. Chalk-pits rich in fish-teeth, &c.

Hastings.Wealden.Lepidotus, Hybodus.

Ilminster, Somerset.Upper Lias.PachycormusandLeptolepis.

Leeds, Middleton Quarry.Carb.Layers offish-coal, abundance of remains ofMegalichthys,Holoptychius, &c. (Geol. Proc.iii. p. 153.)

Lewes, Sussex.Cret.All the fishes of the British Chalk. SeeWond.pp. 356-359.

Lyme Regis.Lias.Dapedius,Hybodus,Squaloraia; and numerous other species and genera.

Newhaven, near Leith.Carb.On the shore, nodules of ironstone with fishes and Coprolites.Amblypterus, Palæoniscus.

Sheppey, Isle of.Tert.Numerous teeth of Rays, Sharks, &c., and other Ichthyolites in great abundance.

Shotover, near Oxford.Kimmeridge Clay.Ischyodus,Hybodus, &c.

Southend, Essex.Eocene.Fish-bones and teeth (Pisodus, &c.) are found on the shore along the foot of the cliff.

Speeton, Yorkshire.Galt.Macropoma Egertoni; and many other fishes.

Steyning, Sussex.Cret.In the marl-pits, Coprolites and teeth of Sharks are abundant.

Stonesfield.Great Oolite.Hybodus,Lepidotus,Leptacanthus, &c.

Swanage.Purbeck.Lepidotus,Hybodus,Ophiopsis, &c.

Thurso, Scotland.Devonian.Asterolepis, &c.

Westbury, near Bristol.Base of Lias.Bone-bed with numerous remains.

Worthing.Cret.Beautiful Chalk fishes in the neighbouring quarries.

FOREIGN LOCALITIES.

⁂ Although the present work is expressly designed as a guide to the British collector, I am induced to subjoin a few foreign localities of Ichthyolites, that lie within the reach of the continental tourist. A detailed account of the most celebrated sites is given by M. Agassiz, Poiss. Foss.

Aix, in Provence.Tertiary.Some of the beds of gypseous marl contain numerous species in abundance.

Eisleben, Upper Saxony.Permian.Numerous Ichthyolites in dark shale.

Glaris, Switzerland.Cret.Immense numbers of fishes in dark schist. The specimens are often contorted, from the contraction of their bodies, during decomposition.

Maestricht (St. Peter’s Mountain).Upper Cret.Numerous teeth, vertebræ, &c. of fishes of the Cretaceous epoch. SeeWond.p. 309. Mansfeld, in Thuringia. Permian. Fishes in copper-slate, in great numbers; many extremely beautiful.

Monte Bolca, or Vestena Nova.Tert.The richest mine of Ichthyolites in the world. A catalogue of the numerous genera and species found in this celebrated locality, is given inPoiss. Foss.tom. iv. pp. 33-52.[573]SeeWond.p. 265.

Mount Lebanon, Asia.Tert.Numerous Ichthyolites, in great perfection.

Œningen.Tert. fresh-water.Many kinds of fishes of the same genera as those which inhabit the great European lakes; as the Perch, Salmon, Eel, Pike, Carp, &c. A list of these Ichthyolites will be found inPoiss. Foss.tom. ii. part ii. p. 78. SeeWond.p. 263.

Saarbrück, in Lorraine.Carb.Amblypterus, and other Carboniferous fishes.

Seefeld, in the Tyrol; on the principal road from Insbruck to Munich.Lias.Abundance of fish in bituminous slate.

Stabia, Italy, at Torre d’Orlando, near Castellamare.Oolite.Beautiful fishes in fissile limestone.

Solenhofen.Oolite.Numerous Ichthyolites; many in great perfection. SeeWond.p. 513.

[573]It is necessary to caution the collector against the frauds practised by the quarry-men, and dealers in fossils, at this and other celebrated foreign localities. Specimens, apparently perfect, are ingeniously constructed from the fragments of various examples. The head of one fish, the body of another, decorated with the fins of a third, and perhaps the tail of a fourth, of different species, or even genera, are dove-tailed together, coloured, and varnished, so as to deceive the common observer, and, occasionally, even the experienced collector. Sponging the specimens with cold water will often detect the imposition; for the colour if artificial will be removed, or rendered paler, while the same process will heighten the natural tints. At Pappenheim, Solenhofen, and other places, where fossil crustaceans, as Shrimps, Prawns, &c. are found in such perfection, the imprints of good specimens are often coloured, and offered for sale; a wet sponge will speedily detect the imposture.

FOSSIL REPTILES; COMPRISING THE ENALIOSAURIANS AND CROCODILES.

"Nous remontons done à un autre âge du monde; à cet âge où la terre n’étoit encore parcourue que par des reptiles a sang froid—où la mer abondoit en ammonites, en bélemnites, en térébratules, en encrinites, et où tous ces genres, aujourd’hui d’une rareté prodigieuse, faisoient le fond de sa population."—Cuvier,Oss. Foss.tom. v. p. 10.

Weadvance now to the investigation of the fossil remains of the more highly organized classes of theVertebrata; the Fishes being the lowest in the scale amongst the beings characterised by an osseous skeleton, with a flexible spinal column, composed of articulated bones, and presenting, in the various classes, orders, genera, and species, numerous modifications of form and structure. The mineralized relics of the vertebrated animals consist, for the most part, of single and displaced bones, or groups of bones and teeth, and the durable portions of the dermal integuments; entire skeletons being of rare occurrence. A knowledge of anatomy and physiology, and access to anatomical and zoological libraries and collections, are therefore indispensable for the cultivation of this most attractive department of Palæontology. Fortunately for the English student, this branch of the science, which a few years since was but little cultivated in this country,[574]has been greatly advanced, by the liberalsupport afforded by the British Association of Science to Professor Owen, whose Reports on the British Fossil Reptiles and Mammalia, published in the Transactions of the Association,[575]should be referred to for more precise and detailed information than can be given in these unpretending volumes. Our remarks will be limited to a general notice of the fossil remains of Reptiles, Birds, and Mammals; with descriptions of such characteristic examples, as will serve to illustrate the nature of the specimens that may probably come under the notice of the collector; or which, from their peculiar characters, are objects worthy his special attention.

[574]SeePetrif.p. 226, note.[575]Report of the Brit. Assoc. 1839 and 1841; see also Trans. Geol. Soc. 2d ser. vol. v. p. 515 (1838).

[574]SeePetrif.p. 226, note.

[575]Report of the Brit. Assoc. 1839 and 1841; see also Trans. Geol. Soc. 2d ser. vol. v. p. 515 (1838).

The Age of Reptiles.[576]—The announcement by the illustrious founder of Palæontology, in the quotation prefixed to this chapter, that there was a period when the lakes, rivers, and seas of our planet were peopled by reptiles, and when cold-blooded oviparous quadrupeds, of appalling magnitude, were the principal inhabitants of the dry lands, was a proposition so novel and startling, as to require the prestige of the name ofCuvierto obtain for it any degree of credence, even with those who were prepared to admit that a universal deluge could not account for the physical changes, which the crust of the earth had evidently undergone. Subsequent observations and discoveries have, however, fully confirmed the truth of this induction, and the "Age of Reptiles" is no longer considered fabulous.

[576]"The Age of Reptiles" was the title given by the author to a popular summary of the evidence bearing on this question: it was published in the Edinburgh Philosophical Journal, 1831. This name is now generally employed to designate the geological epochs characterised by the predominance of oviparous quadrupeds; namely, from the Permian to the Chalk, inclusive.

In some of the ancient fossiliferous deposits,[577]indications of the existence of Reptiles are visible, in the indelible markings left by their footsteps on the muddy banks of rivers, and on the wet sands of the sea-shores, now in the state of layers of marl and sandstone. Here and there in the Devonian,[578]Carboniferous, and New Red formations, teeth and bones are found, presenting unequivocal proofs of the presence of extinct forms of cold-blooded oviparous quadrupeds. As we ascend in the secondary formations, we are suddenly surrounded by innumerable marine and terrestrial reptiles, belonging to species and genera, and even orders, of which no living representatives are known. Throughout the Liassic, Oolitic, Wealden, and Cretaceous epochs, the class of Reptiles was at its fullest development. In the Tertiary periods which succeeded, the Reptiles approach the recent types, and their relics are found intermingled with the bones of mammiferous quadrupeds; thus indicating the commencement of the present condition and relations of the animal kingdom. Referring the reader toBd.p. 165, andWond.pp. 409-444 and 567-588, for a more comprehensive view of this subject, we advance to the examination of some of the fossil genera and species; and we propose, in the first place, to explain a few essential characters of form and structure observable in those durable parts of the skeletons which are most frequently met with in a fossil state; namely, the teeth, jaws, vertebræ, &c., and the osseous appendages of the dermal system.

[577]Devonian rooks of Elgin, North Britain; and the Lower Carboniferous of Pottsville, Pennsylvania.[578]The most ancient Reptile hitherto discovered is theTelerpeton Elginense, from the Old Red of Scotland, which will be described in the sequel.

[577]Devonian rooks of Elgin, North Britain; and the Lower Carboniferous of Pottsville, Pennsylvania.

[578]The most ancient Reptile hitherto discovered is theTelerpeton Elginense, from the Old Red of Scotland, which will be described in the sequel.

The animals comprehended in the Class ofReptiliaconstitute, according to Prof. Owen’s arrangement, eight principal groups, or Orders, as follow:—

Teeth of Reptiles.—The teeth of the animals of this class exhibit considerable diversity of form, but the characteristic type is that of a conical, pointed tooth, with a simple root or fang; for,in no reptile does the base of the tooth terminate in more than one fang, and this is never branched. "Any fossil, therefore, which exhibits a tooth implanted by two fangs in a double socket, must be mammiferous, since the socketed teeth of reptiles have but a single fang; and the only fishes’ teeth which approach sucha tooth in form, are those of a bifurcate base, belonging to certain sharks." (Owen.)

These dental organs are only fitted for seizing and retaining the prey or food; for no living reptiles have the power of performing mastication. In the Crocodiles the tooth has a cylindrical shank, with a conical, longitudinally striated, enamelled crown, having a ridge on each side (Pl. VI. fig. 5). In theLabyrinthodon(a fossil reptile), the cone is more curved and pointed (Pl. VI. fig. 3); in theHylæosaurus, the shank is cylindrical, and the crown expanded and lanceolate, with blunt margins (Pl. VI. fig. 6); in theMegalosaurus, the tooth is laterally compressed, trenchant, and slightly inclined backwards like a sabre, with serrated edges (Pl. VI. fig. 7); in theIguanodon, the shank is cylindrical, and the crown of a prismatic form, greatly expanded, with broad denticulated edges, and longitudinal ridges on one side (Pl. VI. fig. 4, andLigns.221,223). In the Serpents, the teeth are very long and pointed; in the Crocodiles and Lizards, may be seen every modification of the conical form, down to a mere hemispherical tubercle or plate. In the fossilDicynodon, to be hereafter described, the dental system consists of but two tusks or canine teeth, like those of the Walrus, implanted in the upper jaw. The Turtles and some fossil Lacertians are edentulous,i. e.destitute of teeth; their dental organs consisting of the horny trenchant sheaths with which the jaws are covered.

The teeth are very numerous in reptiles; the individuals of some species have more than two hundred. In some genera, they are implanted on the jaws alone; in many, they occupy the palatine, vomerine, and other bones composing the vault of the mouth, as in certain fishes. The teeth are generally anchylosed to the bone; but in some genera they are implanted in distinct sockets, as in the Crocodile and Plesiosaurus; in others, as in the Ichthyosaurus, they are arranged in a deep furrow, and retainedonly by the integuments; in some, they are supported upon an elevated osseous base. In the Labyrinthodonts, and in the greater part of the Serpent tribes, the tooth is implanted by the base in a shallow socket, with which it is confluent.

In most of the Lacertians, or true Lizards, the attachment of the teeth presents a peculiar modification, of which the lower jaw of the Iguana,Lign.205, p. 649, affords a good illustration. The teeth are not placed in sockets, but are attached by the shank to an alveolar plate, or parapet, that extends along the margin of the jaw, as shown infigs.1 and 3; the crowns of the teeth project above this plate, as seen infigs.2 and 4. From the anchylosis of the teeth to the side of the jaw, the Lizards possessing this dental structure are termedPleurodonts.[579]

Back to Index Next