There are no teeth apparent in either jaw: the margin of the upper

maxillary has feeble dentations, but in the lower jaw even these

indications are wanting, and it is probable that this reptile had its

jaws encased by a bony or horny sheath, as in birds and turtles.[664]

(Owen.)

[664] Rep. Brit. Assoc. 1841, p. 150. See also Camb. Phil. Trans, vol.

vii. p. 357, tab. 5, 6.

Thecodontosaurus and Palæosaurus. _Ly._ p. 306, figs. 348,

349.--Numerous bones and teeth of reptiles occur in the Magnesian

Conglomerate, near Bristol, and have been described by Dr. Riley and

Mr. Stutchbury in an interesting memoir to which reference should be

made for details (_Geol. Trans._ 2d ser. vol. v. p. 349, pl. xxix.

xxx.). The bones denote an approach to the lizards; the teeth are

implanted in sockets; these reptiles, therefore, belonged to the group

termed thecodont, and the name _Thecodontosaurus_, given to these

extinct Saurians by Dr. Riley, has reference to this character. The

teeth are pointed, compressed laterally, slightly convex on each side,

with a trenchant, finely serrated edge in front and behind; the fang is

sub-cylindrical. Other teeth from the same deposit, possessing the same

general characters, but distinguished by peculiarities of form, have

been referred to another genus, named _Palæosaurus_. The vertebræ found

associated with the teeth and jaws are biconcave, and are remarkably

characterized by the great depth of the spinal canal in the middle of

the centrum or body of the vertebræ, so that the spinal chord must have

presented a moniliform or bead-like appearance. These reptiles, in

their _thecodont_ type of dentition, biconcave vertebræ, double-headed

ribs, and proportionate size of the bones of the extremities, are

nearly allied to the _Teleosaurus_, (see _ante_, p. 679); but they

combine a lacertian form of tooth, and a lacertian structure of the

pectoral, and probably of the pelvic arches, with these crocodilian

characters; they have also distinctive modifications: such, for

example, as the moniliform spinal chord.[665]

[665] Owen; Rep. Brit. Assoc. 1841, p. 155, &c.

Dicynodon. _Ligns. 232, 233, 234._--This singular fossil reptile was

discovered, by Mr. Bain, in South Africa. It is distinguished, by

some remarkable peculiarities of structure, from other animals of the

Saurian order; of which it represents a new tribe, or sub-order. The

cranium is narrow; the nostrils are divided, as in Lizards, and not

confluent, as in Chelonia; the skull, in other respects, much resembles

in general appearance that of a Turtle; the orbits are large; the

jaws are edentulous, as in the Turtles, with the exception of a pair

of long tusks,[666] implanted in sockets in the upper maxillary bone,

like those of the Walrus; these tusks are of a finer texture than

that of the Crocodile’s teeth, and almost as dense as in the Hyæna.

These creatures present in the most striking manner that blending of

the peculiarities of several existing orders, which is continually

presented to the palæontologist; for with a type essentially lacertian

are combined crocodilian and chelonian modifications. Although no

vestiges of these reptiles have been discovered in England or in

Europe, yet the occurrence of an allied form, the _Rhynchosaurus_

(_Lign. 231_), in our New Red Sandstone, and the probability that the

South African reptiliferous deposits may, from their position, belong

to the Triassic Epoch, induce me to give a somewhat extended notice

of these extraordinary fossils: and I am led to do so on another

account, namely, because the memoir,[667] of which the following is a

brief abstract, is so excellent an example of the manner in which such

investigations should be conducted, so as to arrive at any satisfactory

conclusions as to the characters and relations of the lost types of

beings, whose fragmentary and petrified relics are the only vestiges

that remain.

[666] Hence the generic name, _Dicynodon_: from δις (twice), and

κυνὁδονς (canine tooth).

[667] Prof. Owen’s Memoir on the Dicynodon, Geol. Trans. 2d ser. vol.

vii. pp. 59, _et seq._; and plates iii. to vi.

The fossils under consideration were exhumed some years since by

Mr. Andrew Geddes Bain, from the intensely hard argillo-calcareous

nodules of the sandstone strata which range over an immense tract of

country beyond the mountains north of Capetown,[668] The extensive

series of these and other fossils from South Africa, collected by

the indefatigable labour of Mr. Bain, have lately been deposited in

the British Museum; but the specimens described and figured in Prof.

Owen’s Memoir, above alluded to, are nearly all that have as yet been

successfully worked out from the exceedingly hard matrix in which the

bones are imbedded. These consist of crania and jaws, referable to four

species.[669]

[668] For a notice of the geological structure of this region, see Mr.

Bain’s paper in Geol. Trans. 2d ser. vol. vii. pp. 53, &c.; and the

abstract of a later Memoir by Mr. Bain, in the Literary Gazette, Dec.

18, 1852 (No. 1874).

[669] Namely, Dicynodon lacerticeps (_lizard-head_), D. testudiceps

(_turtle-bead_), and D. strigiceps (_owl-head_), the trivial names

of which have reference to the general form of the head; and D.

Bainii, the largest, but unfortunately as yet the least known species,

which takes the name of the intelligent and energetic discoverer and

collector of the whole.

[Illustration: Lign. 232 and Lign. 233. Dicynodon lacerticeps. (_Owen._)

_South Africa._

(_See Geol. Trans. 2d ser. vol. vii. pl. iii._)

_The letters of reference correspond in the two figures._

Lign. 232. Side view of the Cranium and Lower Jaw: 1/3 _nat. size_.

Lign. 233. Upper aspect of the Cranium: 1/3 _nat. size_.

_Cranium and Upper Jaw._

_a, a._ Intermaxillary bone.

_b, b._ Nasal.

_c, c._ Frontal.

_d, d._ Maxillary.

_e, e._ Prefrontal.

_f, f._ Lachrymal.

_g, g._ Malar.

_h, h._ Post-frontal.

_i, i._ Parietal.

_k, k._ Temporal.

_l, l._ Tympanic.

_m, m._ Mastoid.

_n, n._ Nasal apertures.

_o, o._ Orbits.

_oc, oc._ Basi-occipital.

_t, t._ Temporal fossæ.

_t′, t′._ Canine teeth in the upper jaw.

_Lower Jaw._

1. Dentary bone.

2. Coronoid.

3. Opercular.

4. Angular.

5. Articular.

6. Surangular.

]

The most striking character in these crania is the presence of a pair

of long, sharp-pointed, gently curved tusks, implanted in the superior

maxillary bones, and which descend, one on each side of the fore-part

of the lower jaw, as seen in _Ligns._ 232 and 233, _t_, _t′_. This

is a dental character which, with this exception, is peculiar to the

mammalia (the Walrus, Musk-deer, and Machairodus), and is rare even in

that class.

_Examination of the skull._--One of the crania showed the median

undivided process of a single _intermaxillary_ bone, ascending and

separating _two distinct anterior nasal apertures_; in another, the

boundaries of a very much contracted cranial cavity were evident:

these characters combined to prove that the skulls were referable to

air-breathing oviparous and cold-blooded animals, or Reptiles; but

neither to Crocodilians nor Chelonians, and for the following reasons:--

1stly. The originals were not mammalians; for no mammalian has the

_intermaxillary bone single_ (as in _Lign. 233, a_), or the _external

bony nasal aperture double_; and neither mammalian nor bird has the

cavity for the brain so relatively small as in this fossil.

2dly. They were not Crocodiles; for in all crocodiles the

intermaxillary bone is divided by a suture, and the anterior nasal

aperture is single and on the median line, as in mammalia.

3dly. They were not Chelonians; for all turtles have the nasal opening

single and placed in the middle of the fore-part of the skull, in the

very situation which, in the Dicynodon, is occupied by the convex

imperforate median plate of the broad intermaxillary bone.

4thly. They could not be Fishes, as those animals have no well-defined

external respiratory nasal apertures.

5thly. They were neither Batrachians (frogs) nor Ophidians (serpents);

for, although the reptiles of these two orders have a single

intermaxillary and double nostrils, like the fossils, the latter are

at once separated from them by the presence of a strong and complete

zygomatic arch (_Ligns._ 232 and 233, _g_, _d_), continued from the

tympanic bone to the large immovably articulated superior maxillary.

Lastly, the characters last named, and the presence of vertical

tympanic pedicles (_Lign. 232, l_), suspended by their upper part to

the junction of the zygomatic and mastoid bones, prove the affinity to

the lacertians or true lizards.

These bidental crania have certain characters in common with that of

the Rhynchosaur, which is also, as we have before seen, of the true

lacertian group, but the Dicynodonts are more nearly allied to the

Crocodiles and the Chelonians than the Rhynchosaurus appears to be.

Referring to the original Memoir for anatomical details, I must limit

this notice to a few additional general remarks. Both the jaws are

edentulous, with the exception of the pair of tusks, as in Chelonians;

there are no traces of teeth, or of their sockets, in the lower jaw,

which is short and very deep, and anchylosed at the symphysis, as in

turtles; the alveolar border forms a smooth trenchant edge, which shuts

within the corresponding part of the upper jaw: it is probable that

both jaws were covered by horn, as in the chelonians. The tusks are

implanted in wide and deep conical alveoli in the suborbital part of

the maxillary bone, and project about two inches beyond the sockets

(_Lign. 232_); they are long and pointed, and are directed downwards

and forwards, with a slight backward curve, and slightly converge

towards their extreme points (_Lign. 233_). These teeth consist of

a simple body of unvascular dentine, with a very thin external coat

of enamel. The tooth-ivory is more dense than in any known reptile,

and approaches in its intimate texture that of the canines of the

carnivorous mammals. The base of the tooth has a conical cavity

(_Lign. 234_), indicating a persistent matrix or dental pulp, the

rest of the tooth without the socket being solid. There are no traces

whatever of the germs of successional teeth. It is therefore inferred,

that, like the tusks and scalpriform incisors of mammalia, the canine

or maxillary teeth of the Dicynodon were capable of constant growth

and renovation; thus offering an approach to the typical dentition of

mammalia, unknown in any other reptiles.

As the points of the teeth in the only known perfect specimen are

unworn, it is inferred that these tusks were not employed either as

instruments for obtaining food, as in the Dugong, or for locomotion, as

in the Walrus, but were simply offensive and defensive weapons.[670]

[670] See Prof. Owen’s detailed account of these curious dental organs

in the Memoir already referred to, and in the _Art._ Teeth, in the

Cyclopædia of Anatomy and Physiology.

[Illustration: Lign. 234.

Dicynodon testudiceps. (_Owen._)

(Geol. Trans. 2d ser. vol. vii. pl. v. figs. 3 & 4.)]

Fig. 1.--Longitudinal section of the fang

of the tooth implanted in its

socket: 1/3 _nat. size_.

1_a_.--Transverse section of the tooth.

A few sub-biconcave vertebræ and other undetermined bones were

associated with these remains; and many similar crania, both with and

without the tusks, and other cranial remains with jaws armed with

numerous teeth, as well as indications of smaller reptiles, form

part of Mr. Bain’s collections now in the National Museum, awaiting

the skilful manipulation of the experienced workman to clear away

their hard investing matrix, and the scientific examination of the

palæontologist to elucidate their zoological characters.

Telerpeton Elginense (Mantell). _Ligns._ 235 and 236.--This is

the oldest Reptile yet known.[671] Its remains consist of the

impression[672] of a skeleton of a small, four-footed, vertebrate

animal, on a block of the Old Red or Devonian Sandstone from Spynie,

near Elgin, North Britain. It was obtained by Mr. Patrick Duff, in

1851; and a detailed description of this unique fossil, with an

illustrative plate, will be found in the Quarterly Journal of the

Geological Society, vol. viii. pp. 100, _et seq._; together with a

notice by Captain Brickenden of the geology of the district where

the specimen was found, and a paper on some fossil foot-prints,[673]

discovered by this geologist in the same rock.

[671] The word Telerpeton simply denotes the remote antiquity of this

Devonian reptile of Scotland, τἡλε (far off), ἑρπετον (reptile); the

trivial name, _Elginense_, records the locality from whence it was

obtained.

[672] A model of this most delicate and valuable impression has been

deposited in the palæontological gallery of the British Museum.

[673] A general notice of the fossil foot-prints, or _Ichnolites_, that

have been referred to Reptiles will be given at a subsequent page of

this chapter.

By reference to _Lign. 235_, it will be seen that the cranium is almost

wholly lost; a few conical teeth, mostly of a very small size, were

observed in connexion with the vestige of the jaws. The spinal column

is represented by the impressions of about thirty-six vertebræ, eleven

or twelve of which belong to its caudal portion. The vertebræ present

some faint evidence of their possessing a biconcave form; the length of

one of the dorsal vertebræ is 1/9th of an inch. There are twenty-one

pairs of long slender ribs. The pectoral arch and anterior extremities

have nearly disappeared in the fracture of the stone. The pelvis

and sacrum are very obscure; the latter is formed probably of two

anchylosed vertebra;. The thigh-bones are somewhat curved; the tibia is

gently bowed, and expanded at each extremity. There are no remains of

the feet.

[Illustration: Lign. 235. Telerpeton Elginense (Mantell). _Dev._

_Elgin._

Impression of the skeleton (_nat. size_); showing the outline of

the vertebral column, ribs, pelvis, femora, tibiæ and fibulæ, part

of the caudal series of vertebræ, the left humerus, radius, and

ulna, imperfect traces of the right anterior extremity, and obscure

indications of part of the cranium.]

_a._ The remains of the cranium.

_b, b._ Imprints of portions of the anterior extremities.

_c, c._ Well-defined impressions of the thigh-bones and leg-bones, with

an obscure sub-quadrangular pelvis.

1. One of the teeth: _nat. size_ and _mag._

The structure of this reptilian skeleton, as far as the specimen can

serve to show, indicates a peculiar type of organization, in which,

as in numerous other extinct forms, in this, as in other Classes,

osteological characters are associated which in existing oviparous

quadrupeds are restricted to distinct orders and genera.

[Illustration: Lign. 236.

Telerpeton Elginense (Mantell).

Outline of the restored form of the original reptile: 1/2 _nat._]

The _lacertian_ affinities of the Telerpeton are well marked in the

relative size and form of the bones of its extremities, the situation

of its pelvis, and probably in the articulation and the length of its

ribs; but the contracted, biconcave centrum, and the short neural spine

of the vertebræ, as well as the horizontality of the articulating

surfaces of the zygapophyses, and the general uniformity of character

throughout the spinal column, are to be regarded as _batrachian_

modifications. Probably the original was a peculiar type, which, in the

present state of our knowledge, it would be rash to ascribe to either

order. The length of the original animal could not have exceeded six or

seven inches. _Lign. 236_ represents in outline the probable form of

this small, but most interesting reptile.

V. Pterosaurians, or Flying Reptiles.--Pterodactylus (_wing-fingered

reptile_). _Lign. 237._ _Petrif._ p. 187; _Wond._ p. 577; _Bd._

pl. xxi. xxii.--The extinct reptiles denominated Pterodactyles,

constituting a few genera of an order of Saurians organized for

aërial life,[674] are unquestionably the most marvellous even of the

wonderful beings which the relics of the Age of Reptiles have enabled

the palæontologist to reconstruct. With a long-snouted head and long

neck, much resembling that of a bird, bat-like wings, and a small

trunk and tail, with lacertian affinities in its skull, teeth, and

skeleton, and with a bird-like structure of sternum and scapular arch,

these creatures present an anomaly of structure as unlike their fossil

contemporaries, as is the duck-billed Ornithorhynchus, of Australia,

to existing animals. The cranium, or brain-case, is small; the jaws

are either long, and armed with numerous sharp-pointed teeth, or

toothless, like those of a bird. The teeth of the Pterodactyle are

all laniary; they are simple, of a conical form, recurved, with but

little difference in their form and size, and implanted in distinct

sockets, with wide intervals between each. In some species there are

twenty-eight or thirty in the lower, and twenty-two in the upper jaw.

[674] The only known recent reptile at all analogous is the little

_Draco volans_ of the East Indian Islands; but even this can scarcely

be regarded as a flying animal, its lateral membranous expansions,

which are rather parachutes than wings, and formed by elongated ribs,

not by the fingers, presenting but a rudimentary condition of wings

compared with those of the Bat and the Pterodactyle.

The orbit is very large; the sclerotica consists of an annular row

of bony plates, but less in number than in the Ichthyosaurus; the

external orifice of the nostrils is near the orbits; remains of the _os

hyoides_ (bone of the tongue) have been observed.

[Illustration: Lign. 237. Pterodactylus crassirostris: 1/2 _nat. size_.

_Oolite._ _Solenhofen._]

The cervical vertebræ are large and strong, and capable of great

flexibility forwards and backwards, probably to allow the head to fall

back to the centre of gravity during flight. There are frequently

traces of ossified condition of the tendons of the muscles of the neck.

This is well seen in _P. macronyx_ and _P. crassirostris_ (_Lign.

237_), and is a peculiarity dependent on the additional support required

by the long neck of the animal.

The dorsal vertebræ are from seventeen to twenty in number. The sacrum

is formed by the coalescence of two vertebræ only, as in existing

reptiles, and not of many, as in birds and certain extinct saurians.

The tail is generally short, an unusual character with saurians; but a

species with a long tail occurs at Solenhofen.

There are five toes or digits on each foot; the outer finger of the

fore-arm is immensely elongated, for the support of a membranous

expansion (the impression of this wing-membrane is preserved on the

stone in some examples); and the other digits, of fore and hind feet,

terminated in long curved claws. The size and form of the extremities

show that the _Pterodactylus_ was capable of perching on trees, of

hanging against perpendicular surfaces, and of standing firmly on the

ground, when, with its wings folded, it might crawl on all-fours, and

walk or hop like a bird. A reference to the graphic description of the

characters and probable habits of these beings, by Dr. Buckland, _Bd._

i. p. 221, and the beautiful illustrations accompanying it (_Bd._ ii.

pl. xxi. xxii.), will equally instruct and gratify the reader.

The most perfect examples of the _Pterodactyles_ have been discovered

in the lithographic stone of Monheim, Pappenheim, and Solenhofen, where

their bones are associated with the remains of _Dragon-flies_ (see

p. 551) and other insects. In England, bones of these reptiles have

been obtained from the Lias of Lyme Regis, from the Oolitic slate of

Stonesfield, from the Wealden strata of Tilgate Forest, and the Chalk

of Kent.[675] One of the most interesting British specimens consists

of a considerable part of the skeleton of a species about the size

of a Raven, discovered by the late Mary Anning, in the Lias of Lyme

Regis, and now deposited in the British Museum.[676] It consists of

the principal bones of the extremities, and of several vertebra:, and

is figured and described by Dr. Buckland, _Geol. Trans._ 2d ser. vol.

iii. pl. xxvii. This specimen is distinguished by a greater length of

the claws (whence the name of the species, _P. macronyx_, _long-claw_,)

than in any previously known.

[675] For a detailed description of the Pterosaurian remains from the

English Chalk, with numerous beautiful illustrations, see Prof. Owen s

_Monograph_, published by the Palæontographical Society, 1851. Other

important memoirs on Pterodactyles and their structure, not mentioned

in the text, are, by Von Meyer, in _Nova Acta Acad. Nat. Curios._ vol.

xv. part ii. and _Palæontographica_, part i. 1846; Goldfuss, _Nova

Acta_, vol. xv. part i., and _Reptilien der Vorwelt_, 1831; Prof. Owen

_Quart. Journ. Geol. Soc._ vol. iii. and Mr. Bowerbank, _ibid._ vol. iv.

[676] See _Petrif._ p. 189.

The remains of the Pterodactyles of the Chalk, for the most part,

indicate a large size for the original animals. It has been estimated

that some of these gigantic flying reptiles possessed an extent of wing

surpassing that of the great albatross. The _Pterodactylus Cuvieri_ had

probably an expanse of wing not less than eighteen feet from tip to

tip; another Chalk species, _P. compressirostris_, fifteen feet; whilst

the _P. macronyx_, of the Lias, measured about four feet seven inches

from the extremity of one wing to that of the other.[677]

[677] Bowerbank, _Rep. Brit. Assoc._ 1851, and Owen, _Monograph_, p.

104.

[Sidenote: CHELONIANS.]

VI. Chelonian Reptiles.--Those singular reptiles, commonly known by the

name of Tortoises and Turtles, and designated by naturalists Chelonia

(from _Chelone_, the Greek term for a Tortoise), are distinguished

from all other animals by the osseous cuirass in which their bodies

are enclosed, the head and neck, extremities, and tail, alone being

excluded. This remarkable bony case is produced by the extraordinary

development of the bones of the thorax and back; and consists of an

under (_sternal_) and an upper (_dorsal_) portion. The breast-plate,

or _plastron_, which is the true sternum, is composed of nine pieces

of bone, eight of which are in pairs, and the ninth, or odd plate, is

situated between the four anterior plates. The variation in the form

of these plates is considerable, and affords important distinctive

characters. In the young state of land and fresh-water tortoises, there

are vacancies between the pieces, which are filled up in the adult, the

whole being ultimately united into one bony plate; but in the marine

turtles (and also in the _Trionyces_, or soft tortoises), these pieces

do not completely unite, and interspaces always remain. The bones of

which the dorsal buckler, _carapace_, or upper shield is composed

consist of eight of the ten pairs of ribs, united by a longitudinal

series of angular plates, which are attached to the annular part of

the vertebra throughout the whole, or a great part of their length,

according to the age and species of the individual.[678] Numerous

modifications exist in the form of the buckler, in its flatness or

convexity, in the degree of extension of the ribs, and their angular

plates, and in the characters of the scutes or horny integument with

which the carapace is covered; and with corresponding variations in the

head, and in the locomotive extremities, in the numerous species and

genera of the Chelonian reptiles, according to their adaptation to a

terrestrial, fluviatile, or marine existence.

[678] In the Monograph on Eocene Reptiles, 1849, Prof. Owen has given

a succinct account of the carapace and plastron of the _Chelone_,

and a brief notice of the composition and homologies of these bony

encasements in the Tortoise, with references to more particular and

comprehensive memoirs by himself and others.

The animals of this order are arranged in four principal groups, viz.

the marine, or Turtles (_Chelones_); the fluviatile, or river-Tortoises

(_Trionyces_); the marsh-Tortoises (_Emydes_); and the terrestrial or

land-Tortoises (_Testudines_). The marine Chelonians generally feed

upon vegetables; the _Emys_ and _Trionyx_ approach more nearly to the

terrestrial than to the marine species; they are carnivorous, feeding

on frogs, fishes, fresh-water mollusca, and other small animals. The

_Trionyces_ differ from their congeners in being destitute of a horny

external integument, having no scutes on the buckler or any other

part of the body but the osseous carapace is invested with a strong

tough skin, which equally covers the dorsum and sternum, to which it

firmly adheres; the dermal surface of the bones in these Tortoises is

always rugose, and either granulated, or covered with punctations and

depressions. The buckler of the Trionyces is of a depressed form, with

a soft flattened margin. The Testudinidæ, or land-Tortoises, are too

well known to render any description requisite for our present purpose.

In the marine species, eight pairs of ribs and thirteen plates of the

longitudinal series form the buckler; the ribs or costal plates are

united to each other through a great part of their extent; but towards

their distal or outer extremities each rib contracts, and terminates

in a point, which is supported on a marginal series of bony plates;

the intervals between the ribs are filled up in the living animal by a

cartilaginous membrane which never becomes ossified. This character,

therefore, affords an important aid in the discrimination of the fossil

remains of this family.[679]

[679] The reader will recognise this peculiarity in the gilded skeleton

of the carapace of Turtles, frequently exhibited in the soup-shops of

the metropolis.

In the terrestrial and the marsh Tortoises, the ossification is

complete in the adult state; but in the fluviatile Trionyces, which

are without a horny integument, there is no border, or marginal series

of bony plates, and the extremities of the ribs are therefore always

distinct, and generally have an obtuse extremity. The skeletons of

the three groups present corresponding modifications, and an accurate

knowledge of the osteology of the recent animals is necessary to

enable the palæontologist to arrive at secure conclusions as to the

characters and relations of the fossil species.[680] We can only

advert to one remarkable osteological character,--the construction

of the shoulder, which differs from that of all other animals, in

being situated within the cavity of the thorax, instead of without.

In consequence of this modification, a process of the shoulder-blade

(_scapula_ or _omoplate_), termed the _acromion_, is largely developed,

and the shoulder-bone is tri-mucronate, or three-pronged, consisting of

a short, thick head, containing a concavity (which, with that on the

coracoid-bone, forms a socket for the arm-bone), and of two diverging

branches. This form is so peculiar, that the collector can be at no

loss to recognise the shoulder-bone of a _Chelonian_, should it come

under his notice with other fossil relics (see _Foss. Til. For._ pl.

xix. _fig._ 11). The shoulder-blade and its associated coracoid-bone

undergo certain modifications in the three groups of Turtles, by

which the anatomist may pretty certainly determine the terrestrial,

fluviatile, or marine character of the animals to which they belonged.

The successful application of a perfect knowledge of this department of

osteology, is admirably exemplified in the works to which reference has

been made; and even but a slight acquaintance with its principles will

often enable us to obtain some general information as to the nature and

relations of fossil Chelonians.

[680] The student should consult Cuvier’s _Ossemens Fossiles_, tom. v.

part ii^{me.} chap. ii.: and Prof. Owen’s _Monographs_, published by

the Palæontographical Society, 1849, 1851, 1853. The Penny Cyclopædia,

_Art._ Tortoises, contains an excellent summary of the osteology of

these reptiles, also an abstract of Professor Owen’s Report on the

Fossil _Chelonia_.

The student will remember that all the Chelonians are edentulous, _i.

e._ toothless; their bony jaws being covered by horny sheaths, as in

birds; these mandibles are therefore the only dental organs that can

occur in a fossil state.

[Sidenote: TURTLES AND TORTOISES.]

Fossil Turtles and Tortoises.[681]--Some of the earliest indications of

the presence of Reptiles on our planet are afforded by the foot-prints

of Chelonian animals on the surfaces of the layers of sandstone of

the Old Red formation at Elgin, and of the New Red in Dumfriesshire,

at Storeton, near Liverpool, and at some places in Germany (see _Bd._

i. p. 259, and p. 265, note). But no osseous remains of the animals

of this family have hitherto been found in strata antecedent to the

Oolite. The Solenhofen quarries (Kelheim) have yielded the bones and

carapaces of several Emydian tortoises, and some remains of Chelonians

have been found at Stonesfield, and in the Portland Sandstone.[682]

In the Jura limestone at Soleure, two large species of Emydians have

been discovered. The Wealden and Purbeck formations abound in Chelonian

remains of both fluviatile and marine genera. From the Isle of Purbeck

numerous fine examples have been obtained;[683] my own researches

in the strata of Tilgate Forest (_Foss. Til. For._ p. 60) have also

brought to light several species, and in particular an interesting

Chelonian related to the soft-skinned, fresh-water tortoises,

_Trionyces_ (_Geol. S. E._ p. 255). In the Cretaceous formation of

England the remains of these reptiles are not frequent. The Greensand

of Cambridgeshire (_Rep. Brit. Assoc._ 1841, p. 172,) has yielded a

marine species, and that of Kent a fine Emydian form (Owen, _Monog._

1851); and in the White Chalk a few examples have been obtained, to

which we shall hereafter more particularly allude. On the Continent

fine examples have been found in the slate of Glaris (see _Bd._ pl.

xxv′.); and in the upper Cretaceous strata of the Netherlands, at

Maestricht, and at Melsbroeck, near Brussels, many beautiful specimens

of fresh-water tortoises (_Emydes_), and marine turtles (_Chelones_),

have from time to time been obtained; these are figured and described

by Baron Cuvier (_Oss. Foss._ tom. v. pp. 236, 239). In the Eocene

strata of England, several species of Chelonians have been collected;

of these eleven belong to the marine genus _Chelone_; eight to the

fresh-water _Trionyx_; and eight to the marsh-tortoises, _Emys_ and

_Platemys_. The Isle of Sheppey and Hordwell have yielded the majority

of these relics; the turtles are smaller than the recent analogues,

which now inhabit intertropical latitudes.[684] The Eocene strata

of France contain several fresh-water tortoises, some of which are

referable to the Emydes, and others to the Trionyces. From the gypsum

beds, near Paris, the remains of one or two species of Trionyx have

been obtained (_Oss. Foss._ tom. v. p. 222), of another at Aix, in

Provence, and of three or four species in other localities. A fine

specimen of fresh-water tortoise from Œningen, near Constance, is

described and figured by Professor Bell in Geol. Trans. 2d ser. vol.

iii. The fossil remains of _Testudinidæ_, or land-tortoises, are

exceedingly rare. No well-determined remains are known in the British

strata; the impressions of scutes found in the Stonesfield slate, and

the foot-prints above described, being the only indications of the

existence of these reptiles. The presence of land-tortoises in the

strata of France appears to be equally problematical, for the relics

obtained from Montmartre and Aix (_Oss. Foss._ p. 245) afford no

certain data as to the character of the original.

[681] See _Rep. Brit. Assoc._ 1841, pp. 168, et seq.

[682] See _Rep. Brit. Assoc._ 1841. pp. 160 and 169.

[683] Some of the most beautiful of these almost perfect specimens

have lately been figured and described by Prof. Owen in his Monograph

on the Fossil Chelonian Reptiles of the Wealden and the Purbeck;

Palæontographical Society, 1853.

[684] Rep. Brit. Assoc. 1841, p. 177, and Monograph on Fossil Reptiles,

Pal. Soc. 1849, in which the anatomical details are given with the

characteristic accuracy and minuteness of the author.

The Tertiary formations of India, however, have furnished decided

examples of fossil terrestrial tortoises; and among the innumerable

relics of the beings of an earlier world, which the indefatigable

labours of Dr. Falconer and Captain Cautley have brought to light, and

which those accomplished naturalists have so skilfully developed, are

the remains of land tortoises of prodigious magnitude (_Colossochelys

atlas_); one specimen indicating a length of twelve or fourteen feet,

with a breadth and height of corresponding proportions! These remains

are associated with the bones gigantic extinct mammalia, allied to the

_Palæotheria_ and other pachyderms of the eocene deposits of the Paris

basin; and with those of Emydian and Crocodilian reptiles.[685]

[685] _Petrif._ pp. 11 and 468.

Fossil Marine Turtles.--In illustration of this subject, I select a

specimen discovered in the lower Chalk, at Burham, Kent, which is

remarkable for its beautiful state of preservation, and its peculiar

osteological characters.

[Illustration: Lign. 238. Chelone Benstedi: _nat. size_.

_Chalk. Kent._

The dorsal shield or carapace of this specimen admits of being removed;

and four sternal plates, a coracoid-bone, and several vertebræ are then

exposed.]

Chelone Benstedi. _Lign. 238._--To Mr. Bensted, of Maidstone, whose

discoveries have rendered his quarry of Kentish Bag classic ground to

the British palæontologist, I am indebted for this splendid fossil

turtle. The quarry whence it was obtained is situated at Burham, a

short distance from the banks of the Medway, between Chatham and

Maidstone, and presents a good section of the lower Chalk. This

locality is rich in fossil remains, rivalling in this respect the

quarries near Lewes, Worthing, and Arundel, in Sussex. Two other

fossil Turtles have been obtained from this quarry, and now enrich

the cabinets of Sir P. Egerton and Mr. Bowerbank. Other relics of

Chelonians found in this place are four marginal plates of the

carapace, and fragments of ribs,[686] some marginal plates of a much

larger individual, mandibles, and other fragments, which are noticed

in Prof. Owen’s Monograph, 1851. The specimen, of which _Lign. 238_ is

a reduced figure, consists of the dorsal buckler or carapace almost

entire; it is of a depressed elliptical form, with a longitudinal

median ridge; it is six inches in length, and three and a half inches

in breadth across the middle. It is composed of eight ribs, or costal

plates, on each side the dorsal ridge, which is formed of ten neural

plates; and there is a border of marginal plates. These plates are

united to each other by finely indented sutures, and bear the imprints

of the horny scutes, or tortoise-shell, with which they were originally

invested. The expanded ribs are united throughout the proximal half

of their length, and gradually taper to their marginal extremities,

which are supported by the plates of the osseous border.[687] This

description applies to the specimen as seen in _Lign. 238_; but Mr.

Bensted so skilfully cleared away the chalk as to admit of the

removal of a great part of the dorsal shield, by which means some of

the vertebræ, four sternal (_hyosternal_ and _hyposternal_) plates,

and one of the coracoid bones are displayed. This brief description

will suffice to convey a general idea of the characters of this

fossil, which differs from any known recent turtle, and possesses

some anomalous features, that appear to indicate some slight Emydian

affinities.

[686] See _Geol. Proceed_, vol. iii. p. 299.

[687] See also _Phil. Trans._ 1841, p. 153, pl. xi. and xii.; and

_Palæontograph. Monograph_, 1851, p. 4, plates i. ii. and iii.

[Illustration: Lign. 239.

Beak or Mandible of a Turtle: _nat. size_.

_Chalk. Lewes._]

Among the numerous fossils obtained from the Chalk of Sussex, the only

trace of a Chelonian reptile that has come under my observation is the

bony mandible or beak of a Turtle, _Lign. 239_. Its surface displays

a fibrous cancellated structure, denoting the attachment of the horny

sheath with which, in a recent state, it was covered. More or less

perfect specimens of such mandibles also occur in the Chalk of Kent and

elsewhere, but no bones of the skull have yet been met with in that

deposit. In the Greensand of Cambridgeshire, however, the cranium of a

small turtle has been found. It is figured and described by Prof. Owen

as _Chelone pulchriceps_ (_Monograph_, 1851).

Chelone Bellii. _Lign. 240_, _Petrif._ 155.--In the strata of Tilgate

Forest, fragments of the carapace, of the plastron or sternum, and of

the marginal plates, with some of the bones of the extremities, of a

large marine turtle have been discovered; several specimens are figured

in _Foss. Til. For._ pl. vi. and vii. Some examples must have belonged

to an individual at least three feet in length. Unfortunately, the

specimens hitherto obtained are very imperfect, and do not exhibit

essential distinctive characters, with the exception of the ribs, which

are united to within a short distance of their distal or marginal

extremities; hence the costal interspaces are reduced to much smaller

dimensions than in any recent or fossil Turtles with which I have had

the means of comparing them. The fragment of a rib, imbedded in Tilgate

grit, figured _Lign. 240_, well exhibits this character.

[Illustration: Lign. 240. Chelone Bellii[688] (G. A. M.). _Wealden._

_Tilgate Forest._

Portion of a costal plate, and the extremities of a rib: _nat. size_.

(_Foss. Tilg. For._ pl. vi. _fig._ 2.)]

_a._ The striated pointed extremity of rib.

_b._ The distal portion of the costal plate.

[688] The remains of this reptile were noticed in the "Fossils of

the South Downs, or Illustrations of Geology of Sussex," 4to. 1822,

p. 47, and subsequently figured in the "Illustrations of the Geology

of Sussex, with figures and descriptions of the Fossils of Tilgate

Forest," 4to. 1827, p. 60, pl. vi. and vii.; and this extinct _Chelone_

was regarded as a species, characterized by the great development of

the rib-plates, and named after Professor Bell, the eminent zoologist,

in the first Edition of the "Medals." But in the _Monograph_, _Weald.

Rept._ 1853, this determination has lately been overlooked; and the

specimen figured _Tilg. Foss._ pl. vi. _fig._ 2, is referred to the

newly named _Ch. costata_, characterized by its broad and prominent

ribs. A third name even (_Ch. Mantelli_) has been bestowed on this

interesting fossil, by a German palæontologist.

Fossil fresh-water Tortoises.--The remains of fresh-water Tortoises,

referable to the _Emydidæ_, occur in the Purbeck and Wealden strata

(Owen’s _Monograph_, 1853, and _Rep. Brit. Assoc._ 1841); the

resemblance of some of these to the Jurassic species from Soleure was

noticed by Cuvier (_Oss. Foss._ vol. v.). Among the Chelonian remains

of the Wealden, some of the most remarkable are the costal plates

and other bones of a Tortoise, which in its essential characters is

closely allied to the Trionyces,[689] but differs from the recent

forms, in having possessed a dermal horny integument, formed of

scutes of tortoise-shell. The chelonians of the genus Trionyx (so

named from their having three claws) have the extremities of the ribs

free, and not articulated to a border of marginal plates, and there

are intervals between their costal plates even in the adult state.

The external surface of the bones of the buckler is covered with

granulations, or with little pits, for the attachment of the soft

skin, the only integument with which these animals are invested; and,

being destitute of horny scutes, their bones exhibit no furrows, as

in the other genera. But the fossil rib-plates (see _Lign. 241_) have

a shagreen-like or punctated surface, like the recent Trionyces, and

at the same time bear the imprints of horny scutes; and, instead of

being nearly of an equal width throughout their entire length, as in

the existing species, have one extremity much wider than the other,

as in the land-tortoises. From the slight degree of convexity of

the ribs, it is evident that the carapace was much flattened, as in

the Trionyx.[690] Except in having a defensive dermal integument,

and agreeing in this respect with many of the Crocodilian reptiles,

with which its bones are associated, the original must have closely

resembled the existing predaceous fresh-water soft Turtles; and,

doubtless, like those reptiles, inhabited the muddy beds of lakes and

rivers, preying upon the eggs and young of the larger reptiles, and

on the uniones and other fluviatile mollusca, whose shells are very

commonly found imbedded with its remains.

[689] The relations of these peculiar remains to _Trionyx_ were pointed

out in _Foss. S. D._ 1822, p. 47.

[690] See _Petrif._ p. 157, &c.

[Illustration: Lign. 241. Tretosternon Bakewelli; [691] 1/3 _nat. size_.

_Wealden._ _Tilgate Forest._

(_Foss. Tilg. For._ pl. vi. _fig._ 1.)

One of the costal plates.]

[691] This Tortoise, with the sanction of Baron Cuvier, was described

under the name _Trionyx_, in _Foss. Tilg. For._ 1827, p. 60, and its

distinctive characters were pointed out. In _Geol. S. E._ 1833, p.

255, the specific name _Bakewelli_ was proposed in honour of the late

Robert Bakewell, Esq., whose excellent works have so greatly promoted

the advancement of geology; a privilege to which, as the original

discoverer of the species, and of its zoological relations, I was

fairly entitled. But this name does not appear in the list of British

Chelonians, either in _Rep. Brit. Assoc._ 1841, or in Mr. Morris’s

_Cat. Brit. Org. Rem._ 1843. With a melancholy pleasure I now restore

the name of my lamented friend, as a just, but very inadequate tribute

of respect to his memory.

[Illustration: Lign. 242. Palæophis toliapicus: 2/3 _nat. size_.

_London Clay. Isle of Sheppey._

Six concavo-convex vertebræ of the trunk.]

[Sidenote: FOSSIL SERPENTS.]

VII. Ophidians, or Serpents. _Lign. 242._--The remains of the vertebral

columns of extinct Serpents were discovered many years since in the

London clay of the Isle of Sheppey, and specimens were obtained by

the celebrated Hunter, and preserved in his museum. These specimens,

together with others in the collections of Messrs. Saull, Bowerbank,

Dixon, Combe, and S. Wood, have been figured and described, and their

relations to existing types elaborately worked out, by Professor

Owen.[692] The _Palæophis typhæus_, from the Bracklesham clay, had a

length of about twenty feet, and, from the compressed character of

its caudal vertebræ, was probably a sea-serpent. A somewhat smaller

species also occurs at Bracklesham. The Sheppey specimens are referred

to another species of this extinct genus, namely, the _P. toliapicus_

(_Lign. 242_); it was from ten to twelve feet in length. The remains of

two species of land-serpents, respectively about four and three feet

long, have been found at Hordwell Cliff. These belong to the extinct

genus _Paleryx_, thus named in reference to the near affinities of the

Hordwell vertebræ to those of the recent _Eryx_, one of the Boa and

Python group of serpents.[693]

[692] Geol. Trans. 2d ser. vol. vi. p. 209, &c. pl. xxii.; Rep.

Brit. Assoc. 1841, p. 180; "Dixon’s Geology and Fossils of Sussex,"

pp. 211-217, pl. xii. _fig._ 14; and especially Palæontographical

Monograph, 1850, p. 51, _et seq._; and plates xii. to xvi.

[693] See Monograph on Eocene Reptiles, 1850, from which these notices

of the Eocene Ophidians are abridged.

The vertebræ of Serpents are distinguished by a transversely oblong

anterior concavity, forming a deep cup, and a corresponding posterior

convexity or hall; by the interlocking of the projecting posterior

oblique processes with the anterior pair; and by the oblong tubercle

on each side of the anterior part of the body of the vertebra, for

moveable articulation with the head of the ribs; a spinal column thus

constructed combines in the highest degree perfect flexibility with

great strength.

In addition to the ophidian relics above referred to, fossil vertebræ

of a small serpent (_Palæophis?_) have been found in the Eocene sand

below the Bed Crag, at Kyson in Suffolk;[694] a locality that has

yielded other organic remains of great interest (see chap. xix.; and

_Wond._ p. 258). The only fossils of this order of reptiles known to

Baron Cuvier appear to have been some vertebræ from the bone-breccia of

Cette (_Oss. Foss._ tom. iv. p. 177).

[694] Rep. Brit. Assoc. 1841, p. 181; and Monograph, 1850, p. 66.

Fossil eggs of snakes are occasionally met with in a comparatively

recent limestone, of fresh-water origin, in Germany, near Offenbach,

associated with shells of land and fresh-water molluscs. Like the

turtles’ eggs on the shores of Ascension Island, these ova were

probably laid in the moist mud, and became encrusted and preserved by a

deposit of tufa.[695]

[695] Quart. Journ. Geol. Soc. vol. vi. part 2, p. 42.

[Sidenote: BATRACHIANS.]

VIII. Batrachians.--The reptiles termed Batrachians (from the Greek

name for Frog) are characterized by the metamorphoses which they

undergo in the progress of their development from the young to the

adult state; the Frog, Toad, and Newt are familiar examples of this

order. Their organs of aërial respiration consist of a pair of lungs;

but in their young state they are provided with gills, supported, as

in fishes, by cartilaginous arches. These organs disappear, in most

species, when the animals arrive at maturity; but in a few genera, as

the Siren and Proteus, they are persistent. The skeletons of these

reptiles present corresponding modifications. The skull is, for the

most part, much depressed, and the cerebral cavity small; it is united

to the vertebral column by two distinct condyles, situated on the

sides of the occipital or cranio-spinal aperture.[696] The vertebral

column, in some genera (as, for example, in the common frog), is very

short, and is reduced to eight or ten bones, the caudal vertebræ being

fused into a long cylindrical style; but in the higher organised

Batrachians the spine is composed of concavo-convex vertebræ, as in

the Crocodile: in the lower type, as the Siren, Proteus, and Axolotl,

the vertebræ are biconcave, as in numerous species of fossil Saurians.

The ribs are merely rudimentary, being very short and few; a condition

which has relation to the mode of reproduction in these animals, the

eggs being accumulated and shed at once.[697] Some of the Batrachians

are edentulous, but others have numerous small, conical, uniform,

closely-arranged teeth, placed either in a single row, or aggregated

like the rasp-teeth in fishes.[698]

[696] Saurians, like birds, have a single occipital condyle.

[697] See Dr. Roget’s _Bridgewater Essay_, p. 395.

[698] The variations in the dental system of these animals are given in

_Odontography_, chap. ii. p. 187.

[Sidenote: FOSSIL BATRACHIANS.]

Batracholites; or fossil remains of Batrachians.--The skeletons,

vestiges of the soft parts, and imprints of the feet of several genera

of Batrachians occur in a fossil state in tertiary deposits, all of

which, like the existing races, appear to belong to fresh-water or

terrestrial species. In the pliocene or newer tertiary strata, on the

banks of the Rhine, at Œningen, and in the _papierkohle_ of the Eifel,

several species of Frog, Toad, and Newt, have been discovered. Fossil

frogs of a small species, very similar to the recent, occur in numbers

in a dark shale, overlaid by basalt, in the vicinity of Bombay.[699]

[699] Quart. Geol. Journ. vol. iii. p. 221.

A celebrated fossil of this class is the gigantic Salamander

(_Cryptobranchus_), three feet in length (_Lign. 243_), found at

Œningen (see _Wond._ pp. 263, 580), which a German physician of some

note (_Scheuchzer_) supposed to be a fossil man![700] and he described

it in an essay, entitled "_Homo diluvii testis et Theoscopos_," as

being the moiety, or nearly so, of a human skeleton, with the bones and

flesh incorporated in the stone.[701] A fine example of this fossil

Salamander is preserved in the British Museum (_Petrif._ p. 186).

[700] Phil. Trans, for 1726, vol. xxxiv.

[701] Ample description and figures of this highly interesting fossil

are given by Cuvier, _Oss. Foss._ tom. v. part ii. p. 431, pl. xxv.

xxvi.

[Illustration: Lign. 243. Cryptobranchus Scheuchzeri: 1/11 _nat. size_.

_Tertiary._ _Œningen._]

[Sidenote: LABYRINTHODON.]

Labyrinthodon. _Ly._ p. 290-293; _Wond._ p. 550. By far the most

interesting evidence of the existence of Batrachian reptiles in the

earlier ages of our planet has been afforded by Professor Jäger’s

discovery of the skull, teeth, and other remains of gigantic extinct

animals, allied to the Salamander, in the Upper New Red Sandstone

(_Keuper_) of Wirtemberg.[702]

[702] Über die Fossile Reptilien welche in Würtemberg aufgefunden

worden sind, von Dr. Geo. Friedr. Jäger. 4to. Stuttgart, 1828. See also

Hermann von Meyer’s Notice of the Saurians of the Muschelkalk, Banter

Sandstein, and Keuper, _Quart. Geol. Journ._ vol. iv. pt. ii. p. 40.

These remains were referred by this eminent physician and naturalist

to saurian genera, although the double condyle of the occipital bone

indicated Batrachian affinities. It was reserved, however, for our

distinguished countryman, Professor Owen, to correct the error into

which the German _savant_ had fallen,--remove the obscurity in which

the subject was involved,--determine the natural relations of the

original,--and develope a modification of dental organization of the

most unexpected and interesting character.

Dr. Lloyd, of Leamington, having discovered some fossil teeth and

bones in the light-coloured sandstone of the New Red, at Warwick and

Leamington, submitted them to Professor Owen, who, struck with their

general resemblance to the teeth of the gigantic _Salamandroïdes_ of

Wirtemberg, instituted a microscopic examination of the British and

German specimens. The result proved that the teeth from both localities

possessed a remarkable and complicated structure, produced by the

convergence of numerous inflected folds of the external layer of cement

towards the pulp-cavity; to which, as we have already seen (p. 666),

a very slight approach was made in the tooth of the Ichthyosaurus,

and a still closer approximation by the teeth of certain fishes

(_Lepidosteus_, p. 616). From the intricate meanderings or labyrinthine

inflections observable in the sections of these teeth, Professor Owen

has given the name of _Labyrinthodon_ to these extinct Batrachian

reptiles, and has determined five British species; one of which (_L.

Jægeri_) he conceives to be identical with a species described by my

friend, Dr. Jäger.

The remains of the skeletons of these reptiles, hitherto found in

Warwickshire, consist of portions of the cranium, and of the upper and

lower jaws, with teeth, vertebræ, a sternum, and some of the bones of

the pelvis and the extremities. From a specimen (of _L. scutulatus_)

consisting of an aggregated group of bones, imbedded in sandstone,

comprising four vertebræ, portions of ribs, a humerus, a thigh-bone,

and two leg-bones, with several small osseous scutes, it appears

that one species, at least, resembled the Crocodiles in its dermal

structure. But Professor Owen remarks, that this modification of the

dermal system does not affect the claims of the Labyrinthodonts to be

considered as Batrachians, although all the known living species of

this order are covered with a soft, lubricous, naked integument; for

the skin is the seat of the most variable characters in all animals;

and the double occipital condyle, the simple lower jaw, the palatal

vomerine bones, and the teeth of these fossil reptiles must be deemed

decisive of their essentially Batrachian nature.

From the specimens of the cranium the important fact has been

ascertained, that the Labyrinthodonts had subterminal nostrils leading

to a wide and shallow nasal cavity, which is separated by a broad

and almost continuous palatal flooring from the cavity of the mouth;

indicating, by its horizontal position, that the posterior apertures

were placed far behind the external nostrils; whereas in the recent

air-breathing Batrachians the nasal canal is short and vertical, and

the inner apertures pierce the anterior part of the palate. The nasal

cavities in the Frog are vertical; for this reptile swallows air. The

Labyrinthodonts must, therefore, have breathed air like the Crocodiles,

and were probably provided with well-developed ribs, and not mere

rudimentary styles, as in most living Batrachians.

Tooth of the Labyrinthodon. _Pl. VI. fig. 3._--The tooth of the

Labyrinthodon is of a conical figure, very slightly recurved, and

marked externally with shallow, fine, longitudinal strife. _Pl. VI.

fig. 3^a_, represents (1/2 _nat. size_) a specimen presented to me by

Dr. Jäger. The tooth is implanted, by a single fang, in an alveolar

groove to which it is anchylosed. It consists of a simple central

pulp-cavity, surrounded by a body of dentine, which has an external

thin coat of cement; and a vertical duplication or fold of this cement

penetrates the substance of the tooth at each of the striæ, which are

arranged at intervals of about one line around the entire circumference

of the tooth. The inflected folds of cement extend inwards towards the

centre, in a straight direction for about half a line, then become

undulated, and finally terminate in a dilatation or loop, close to the

pulp-cavity, from which it is separated by a thin layer of dentine.

Within these inflections of the cement, the dentine, or tooth-bone, is

similarly disposed; a layer of dentine lining the folds of cement, and

having corresponding interspaces, which are filled up by the processes

from the pulp-cavity. It is this blending of the cement and dentine

in labyrinthine folds, that gives the peculiar character observable

in transverse sections of the teeth. _Pl. VI. fig. 3^a_, represents

a transverse section of half the diameter of the tooth; the vacancy

in the middle of the line at the bottom is a section of half the

pulp-cavity. _Fig. 3^b_ is a vertical section of a fragment near the

summit of the tooth; and _fig. 3^c_, a highly-magnified view of one of

the anfractuosities, showing a fold of cement, surrounding a fold of

dentine, and in the centre of the latter the termination of a process

of the pulp. The section of the tooth of the Ichthyosaurus, _Pl. VI.

fig. 9_, shows the most simple modification of this structure; the

apparent complication of that of the Labyrinthodon arises from the

inflections of the three elements of dental organization being more

numerous and diversified. But the beautiful plates and the graphic

description of the original discoverer must be seen and perused to

obtain an adequate idea of the exquisite structure of the fossil

teeth; for the distribution of the extremely minute calcigerous

tubes of the dentine is as diversified as that of the constituent

substances. And even after viewing these _chefs-d’œuvres_ of structural

delineations, should the reader have an opportunity of examining a

transverse section of a tooth under the microscope, he will feel how

feebly any engraving can represent the characters of the original.[703]

[703] Professor Owen’s Memoir on the Labyrinthodonts, in _Geol. Trans._

2d ser. vol. vi. pp. 503-543, with five admirable lithographs by that

excellent artist, Mr. Scharf, and the description of the structure

of the teeth, _Odontography_, p. 195, pl. lxiii. lxiv. should be

consulted. See also _Cyclop. Anat._ Art. Teeth.

[Sidenote: ARCHEGOSAURUS.]

Archegosaurus. _Lign. 244_, _Ly._ p. 336, _figs._ 384,[704] 385.--The

occurrence of reptilian remains in deposits of higher antiquity than

the Triassic was first established in 1844, by the discovery of the

skull and other portions of the skeleton of an air-breathing reptile,

the _Apateon pedestris_, related to the Salamanders, and about three

feet in length, in the coal of Münster-Appel in Rhenish Bavaria.

In 1847 Professor Von Dechen obtained, in nodules of argillaceous

ironstone, from the coal-field of Lebach, in the district of Saarbrück,

three species of the same type of reptiles; these have been described

by Goldfuss, under the name of _Archegosaurus_.[705] One of them was

well known to collectors, but had previously been regarded as a fish

(the _Pygopterus lucius_ of M. Agassiz).

[704] The original of this figure of _Archegosaurus minor_ is now in

the British Museum.

[705] See a notice of the researches of Goldfuss, Von Dechen, and Von

Meyer in the geological and zoological history of this interesting

group of batrachoid reptiles, _Quart. Journ. Geol. Soc._ vol. iv. part

ii. (Miscell.) p. 513, _et seq._

The skull and portions of the trunk of this species (_A. Dechenii_),

see _Lign. 244_, indicate an animal three and a half feet in length.

Seventeen dorsal vertebræ, imprints of the ribs, and remains of the

extremities, have been collected. The jaws to beyond the orbit

have small fine conical teeth, longitudinally striated. The eye was

furnished with an osseous ring. The skin, of which a considerable part

was detached, was covered by long, narrow, wedge-shaped, horny scales,

arranged in rows (_Lign. 244_). The cranial bones are characterized

by reticulating grooves and pittings, similar in character to the

reticulate markings on the cranial bones of the Labyrinthodon, but of

a more delicate sculpturing. The original reptiles were quadruped; the

fore and hind feet had distinct toes; but the limbs were feeble, and

only capable of swimming, or, when on land, of a slow creeping movement.

The Archegosaurus is closely allied to the Labyrinthodonts;[706] and,

in the words of Professor Owen,[707] it is "essentially Batrachian,

and most nearly allied to the perennibranchiate, or lowest or most

fish-like of that Order of Reptiles."

[706] We may remark that in the opinion of Dr. Goldfuss and Von Meyer

(_loc. cit._) the Labyrinthodon and the Archegosaurus are saurian

forms connecting the Crocodiles and the Lizards, and representing in

the ancient fauna an arrested or "permanent larva-condition of the

loricated reptiles, as the sirens do among the recent batrachians."

Professor Owen’s estimation of the affinities of these genera is stated

above, and in the _note_ at p. 55, Geol. Journ. vol. iv. part ii.

[707] Quart. Geol. Journ. vol. ix. p. 69.

Parabatrachus Colei.--Under this appellation Professor Owen has lately

described (_Quart. Geol. Journ._ vol. ix. p. 67, pl. ii. _fig._ 1,)

a batrachoid fossil, consisting of cranial and maxillary bones with

teeth, probably from the shale of the Glasgow coal-field, at Carluke,

Lanarkshire. The slab of coal-shale in which the specimen is imbedded

contains also a large scale of the _Holoptychius_ (see p. 618).

[Sidenote: DENDRERPETON ACADIANUM.]

Dendrerpeton Acadianum.[708] (_Quart. Journ. Geol. Soc._ 1853, pp.

58-67, plates ii. and iii.)--The remains of a reptile and a land-shell,

resembling a _Pupa_, were discovered in 1852, by Sir C. Lyell and

Mr. J. W. Dawson, in the interior of an erect stamp of a fossil tree

(_Sigillaria_), in the coal-measures at the South Joggins cliffs,

Nova Scotia. These remains were fully described by Professor Jeffries

Wyman, of Harvard University, U. S., and Professor Owen in the Appendix

to the Memoir by Sir C. Lyell and Mr. Dawson, in the Journal of the

Geological Society, vol. ix. Some of the bones were recognised as

having a near resemblance to those of the recent _Menobranchus_ and

_Menopoma_ (Perennibranchiate Batrachians, inhabiting North American

fresh-waters); the sculptured cranial bones are analogous to those

of the _Labyrinthodon_ and _Archegosaurus_; and the teeth have a

Labyrinthodontoid structure: numerous, small, concentrically striated

scutes, of an irregular oval shape, accompany the bones and teeth.

[708] The _Tree-reptile of Acadia_ (Acadia being the ancient Indian

name for Nova Scotia).

[Illustration: Lign. 244. Archegosaurus Dechenii. 1/2 _nat. size_.

_Coal Formation._ _Saarbrück._]

Fig. 1.--The cranium and part of the lower jaw.

2.--A portion of the skin, or dermal scutes, magnified.

3 and 4.--Magnified figures of two teeth.

The conclusions arrived at by the eminent comparative anatomists to

whose examination the remains in question were submitted, show that the

character of the fossils are those of Perennibranchiate Batrachians;

that, with regard to the long bones, it is not improbable that the

corresponding bones in the _Archegosaurus_ (p. 745) and _Labyrinthodon_

(p. 741) would present similar correspondences with those of the

existing perennibranchiates; and that, although the _Dendrerpeton_

cannot be referred to any known form of the two genera just mentioned,

yet there exists strong evidence of its close affinity with these

extinct Batrachians.

The _Dendrerpeton Acadianum_ was probably between two and three feet in

length. A series of minute biconcave vertebræ were found with the other

remains in the erect tree, these, however, from their relatively small

size, and from other characteristics, are regarded by Professor Wyman

as having probably belonged to some other associated reptile.

The Labyrinthodont reptiles have been regarded as characteristic of the

Permian and Triassic epochs, their remains being found in Germany and

England in rocks of that age. The commencement of the existence of this

family of sauroid-batrachians, however, is of greater antiquity, since

their relics also occur in the formations of the Carboniferous epoch.

The _Archegosaurus_ (p. 745), a batrachian but slightly removed from

the true Labyrinthodont type, has left its well-characterized remains

in the Coal of Germany; the _Parabatrachus_, in that of Scotland;

and the allied _Dendrerpeton_, in the Nova Scotian coal-field. This

last-mentioned great carboniferous formation has, however, afforded

fossil evidence of the existence of the true Labyrinthodonts in the

Coal-period, for some cranial bones, imbedded in a mass of Pictou

coal, lately sent to England by Mr. J. W. Dawson, and the subject

of a Paper by Professor Owen, read before the Geological Society,

were demonstrated by that distinguished palæontologist to have close

affinity with the corresponding parts of the skull of the Triassic

genera _Capitosaurus_ and _Metopias_.

[Sidenote: ICHNOLITES.]

Ichnolites (_Foot-prints on stone_). _Lign. 245._--The sandstones and

mud-stones of many localities retain the track-prints of animals that

have passed along on the surface of the beds when in a soft state.

These foot-prints, or _ichnolites_, either occur as impressions on the

surface originally marked lay the animal in the act of progression,

or as the reverse of such impressions, being casts _in relief_ on the

under side of the layer covering the surface originally impressed. Such

indications of footsteps and trails have been noticed especially in the

forest marble, a member of the Lower Oolite series, where Crustacea

and Mollusks have left their markings, and in the New Red Sandstone,

where the indications of reptilian quadrupeds and of bird-like

bipeds[709] have been here and there preserved in great distinctness.

Tracks referable to Crustaceans have been found by Mr. W. E. Logan,

on the very ancient and rippled surfaces of the Potsdam Sandstone of

North America (see p. 543, _note_); and very lately Mr. J. W. Salter

has communicated to the Geological Society the discovery of markings,

referred by him to the little entomostracous Hymenocaris (see p. 526),

on the Lower Lingula Flags of North Wales,--deposits of as great an

age, if not older. The most ancient reptilian ichnolites are those

discovered by Capt. L. Brickenden[710] in the Old Red, at Cummingston,

near Elgin, which have some resemblance to the track of a club-footed

Chelonian (_Ly._ _fig._ 521); and those of the Devonian sandstone of

Sharp Mountain, Pennsylvania, discovered by Mr. I. Lea,[711] which

exhibit distinct toes, and are probably allied to the Cheirotherian

ichnolites, about to be mentioned, as are also other ancient fossil

foot-tracks in the Carboniferous deposits[712] of Pennsylvania, which

are figured and described in _Ly._ pp. 337-340.

[709] See Ornithoidichnites, in chap, xviii.

[710] Quart. Geol. Journ. vol. viii. p. 97, pl. iii.

[711] Across the ridges of the ripples on this slab is a narrow groove,

passing along between the two rows of foot-prints; this might have been

made by the body or the tail of the animal. _Rep. Brit. Assoc._ 1849,

Sect. pp. 56 and 134; and _Trans. Americ. Phil. Soc._ new series, vol.

x. part ii. plates xxxi. and xxxii.

[712] With regard to the distribution of reptilian life during the

carboniferous and succeeding epochs, see above, page 748.

The sandstones of the New Red or Triassic series frequently retain the

track-prints of animals, and numerous notices of such occurrences have

been published.[713] In addition to the account of these invaluable

evidences of the existence of bygone creatures that is here given, the

attention of students is especially directed to Dr. Buckland’s most

interesting description and illustrations of such as were known when

his Treatise was published (_Bd._ i. p. 259, &c.; and ii. p. 36, pl.

xxvi. &c.).

[713] The following are the principal notices of ichnolites by English

authors which are not referred to in the text:--Cunningham, Yates,

and Egerton on Cheirotherian traces in Cheshire, _Geol. Proc._ vol.

iii. pp. 12-15; Dr. Black on foot-prints at Runcorn, _Quart. Geol.

Journ._ vol. ii. p. 65, pl. ii.; Mr. Cunningham. _Liverpool Lit. and

Phil. Proc._ 1848, p. 129, plates iii.-v.; Mr. Hawkshaw on the New Red

with foot-prints at Lymm, _Rep. Brit. Assoc._ 1842, Sect. p. 56; Mr.

Rawlinson on the same, _Quart. Geol. Journ._ vol. ix. p. 37; Prof.

Harkness on the track-bearing beds of Dumfriesshire, _Rep. Brit.

Assoc._ 1850, Sect. p. 83; _Quart. Geol. Journ._ vol. vi. pp. 389 and

393; and _Annals Nat. Hist._ 1850, vol. vi. p. 203; Sir W. Jardine,

_Annals Nat. Hist._ _loc. cit._ Foreign authorities may be found by

reference to Pictet’s _Traité de Paléontologie_, a new and enlarged

edition, vol. i. 1853, p. 567, _et seq._

The imprints of the feet of some large quadrupeds, having the

fore-paws much smaller than the hinder, have been found in Saxony

(see _Wond._ p. 555, _Bd._ p. xxvi.); and also in strata of the same

age in Warwickshire and Cheshire. The quarries at Storeton Hill,

near Liverpool, are celebrated for the abundance and variety of these

imprints.[714] Some of the strata of sandstone in this locality are

divided by thin beds of clay; a lithological structure which admits of

the ready separation of the stone in the direction of the sedimentary

planes.

[714] The Museums at Warwick, Warrington, and Liverpool are rich in

impressed slabs from the Triassic districts. Numerous fine specimens

may be also seen in the Museum of the Geological Society, Somerset

House, the Museum of Practical Geology, in Jermyn Street, and in the

British Museum (see _Petrif._ pp. 14 and 63).

[Sidenote: RAIN-PRINTS ON STONE.]

Imprints are found on the face of each successive stratum; and on

some of the layers, not only the tracks of animals that have walked

over the clay when soft are distinctly observable, but the surface is

often traversed with casts of the cracks caused by the desiccation

of one layer of clay previously to the deposition of the succeeding

layer of sand or mud; and it often presents a blistered or warty

appearance, being covered with either little hemispherical eminences

or depressions, which an accurate investigation of the phenomenon has

proved to have been produced by showers of rain (_Ly._ figs. 526-528).

On the slabs of sandstone, the forms of the sun-cracks, rain-drops, and

foot-prints appear in relief, being casts moulded in the soft clayey

mud upon which the original impressions were made; while on the clay or

shale, corresponding depressions are apparent.[715]

[715] The impressions of rain-drops on stone were first noticed, and

their origin explained, by Mr. Cunningham. _Geol. Proc._ vol. iii.

p. 99. See also an interesting Paper by Sir C. Lyell, _Quart. Geol.

Journ._ vol. vii. p. 240.

The foot-prints on these strata are of several kinds; some appear to

have been produced by small reptiles and crustaceans; but the principal

imprints are identical with those which have been observed in Saxony,

and are referable to some large quadruped, in which the fore-feet

were of a much smaller size than the hind-feet (_Lign. 245_). From

a supposed resemblance of the imprints to those of a human hand,

Professor Kaup proposed the name of _Cheirotherium_, to designate the

unknown animal which had left these "footsteps on the sands of Time."

But since Professor Owen’s discovery, that the bones and teeth of

reptiles found in similar strata in Warwickshire belong to gigantic

Batrachians, and since the fore and hind-feet of the frog-tribe are

often as dissimilar in size as the impressions of the _Cheirotherium_,

it has been suggested, with much probability, that the foot-prints in

question may be those of Labyrinthodonts; but until the form of the

feet of these extinct Batrachians can be ascertained, this inference

must be regarded as conjectural (_Ly._ _fig._ 331).

[Sidenote: CHEIROTHERIUM.]

[Illustration: Lign. 245. Cheirotherium Kaupii. 1/8 _nat. size_.

Casts of the foot-marks of a gigantic extinct Batrachian, probably a

Labyrinthodon; with casts also of the cracks of the opposed surface.

_Trias._ _Hessburg, near Hildburghausen, Saxony._]

Fig. 1.--Casts of the imprints of a hind and a fore-foot of the same animal.

2.--Similar tracks of another individual on the same stone.

Allusion has already been made to foot-prints, supposed to be those of

tortoises (see p. 729), on slabs of Triassic sandstone in Scotland.

Of these there are five species at Corncockle Muir, in Dumfriesshire:

they are termed _Chelichnus_ by Sir W. Jardine, who has lately

described them in his _Ichnology of Annandale_, a splendid folio work,

illustrated with full-sized lithographs, coloured after nature. They

are accompanied with three other forms of footstep (_Herpetichnus_,

_Batrachnis_, and _Actibatis_), one of which Sir W. Jardine regards as

indicative of an animal probably of a saurian form.

At Grinsill quarry, from which the remains of the _Rhynchosaurus_ (p.

712) were obtained, some small foot-prints have been observed, which,

with some probability, have been referred to that animal (_Rep. Brit.

Assoc._ 1841, p. 146).

A beautifully distinct series of foot-prints, with the mark of a

trailing tail, on a rippled slab from the New Red of Shrewley Common,

Warwickshire, are figured and described by Strickland and Murchison

(_Geol. Trans._ 2d ser. vol. v. pl. xvviii.). This ichnolite has

been provisionally assigned by Professor Owen to _Labyrinthodon

leptognathus_.[716] Similar impressions occur in company with other

Cheirotherian imprints at Storeton Hill and at Grinshill.

[716] Geol. Trans. 2d ser. vol. vi. p. 525. The probable relations of

_Cheirotherium Hercules_ to _Labyrinthodon Jægeri_, and of _Ch. Kaupii_

to _L. pachygnathus_, are pointed out by the same high authority,

_ibid._ pp. 537, 538.

[Sidenote: ON COLLECTING FOSSIL REPTILES.]

On Collecting the Fossil Remains of Reptiles.--The length to which this

article has extended, compels me to omit a retrospect of the geological

distribution of fossil reptiles; and I must refer the reader to the

brief review of the Age of Reptiles in _Wond._ p. 568, _et seq._, and

_Petrif._ p. 147, &c., and close this chapter with some directions

for collecting reptilian remains, and a list of a few British

localities.[717]

[717] An able Summary on British Fossil Reptiles is appended to Prof.

Owen’s Report, _Rep. Brit. Assoc._ 1841, p. 191.

The fossil _Teeth of Reptiles_ are commonly found in as perfect a state

of preservation as those of fishes; and require but the usual care for

their preservation. But the collector should assiduously search for

vestiges of the jaw and cranium; and it is desirable to place in the

same drawer any undetermined bones found associated with the teeth;

as they may ultimately afford some clue to the nature of the original

animal. The microscopical examination of the teeth is to be conducted

in the manner previously directed (p. 639); but for valuable specimens

the lapidary should be employed, and transverse sections made from near

the apex, the middle, and base of the tooth; if due care be taken,

several slices may be obtained from one specimen. I have ten slices

from one tooth of the Labyrinthodon. The bones imbedded in limestone

generally partake of the chemical character of the rock, and are

often permeated with calcareous spar; mere fragments, when polished,

frequently display the internal structure.

The suggestions for repairing fossil bones (p. 46) render further

instructions on that head unnecessary; and the description of the

development of the specimen of Hylæosaurus (p. 689) affords a practical

lesson to the young collector.

When a vertebra is found in an imperfect state, it should be closely

examined on the spot, and, if it present proofs of recent fracture, the

detached processes should be sought for; even if the body of a vertebra

be imbedded in stone, and the processes appear to have been broken off

before it was enveloped in the rock, the corresponding parts will often

be found in the same mass of stone. There is in the British Museum a

very fine Saurian vertebra imbedded in a large slab of Tilgate stone,

in which the spinous process is seen lying in the same block, several

inches distant from the centrum or body; when observed in the quarry

the latter only was exposed, and I was about to detach it from the

slab, for the convenience of carriage, when I perceived indications of

the spinous process. The vertebra was therefore allowed to remain, and

the stone chiselled away, so as to expose the spine; and the specimen

then displayed its present interesting character.

It may frequently happen that a fragment of a large bone,--as, for

example, the thigh-bone of the Iguanodon,--may be obtained from a

quarry; and after an interval of some weeks the corresponding portions

be discovered. This was remarkably exemplified in the first specimen

which revealed to me the peculiar characters of the femur of the

Iguanodon. The lower part, or condyloid extremity, of a gigantic

bone, firmly impacted in a block of Tilgate-grit, was found in a

quarry near Cuckfield; it was evidently but a fragment of the fossil,

for the fracture was recent; I therefore requested the quarry-men

to make diligent search for the corresponding portion, but without

success. Several months afterwards, upon a fresh explosion in the

quarry, the head of a large bone was found loose among the fallen

mass; but there were no indications that it belonged to the specimen

previously found; and it was regarded as another relic of some one

of the colossal animals whose bones were distributed in the Wealden

deposits. Teeth, fragments of bones, and other fossils were from

time to time obtained from the same quarry; and among these a huge

quadrangular fragment of bone, similar to the enormous mass that had so

long been in my possession, and had defied all attempts to ascertain

its character.[718] It was some time before it occurred to me, that

the three portions of unknown colossal bone might belong to the same

specimen; but eventually they were found to correspond, and upon

cementing them together, the femur of the Iguanodon was, for the first

time, developed.

[718] The fragment alluded to is figured, _Foss. Til. For._ pl. xviii.

The figures in _Lign. 206_ will assist the collector in recognising

the different vertebral processes, even when occurring as detached

fragments. When specimens are evidently rolled or water-worn, there

is, of course, no probability that the corresponding portions will be

met with. Every fragment of a bone the nature of which is not obvious

should be carefully preserved; for sooner or later its characters may

be ascertained. It is scarcely necessary again to remind the collector,

that search should be made for indications of the soft parts around the

bones; the specimen of the paddle of the Ichthyosaurus (_Lign. 215_, p.

669), with its integument, must have impressed this fact too strongly

on the mind to be soon forgotten. If the impression of the extremities

of a bone, of which a fragment only remains, be observed, the block of

stone should be preserved, as a cast may be taken, and the entire form

of the original be ascertained.

BRITISH LOCALITIES OF FOSSIL REPTILES.

Aust Cliff, near Bristol. _Lias._ Plesiosaurus.

Barrow-on-Soar. _Lias._ Ichthyosaurus, Plesiosaurus.

Bath. _Lias._ Plesiosaurus.

Battle, Sussex. _Wealden._ Iguanodon, Cetiosaurus, Goniopholis,

Chelonians.

Binstead, Isle of Wight. _Upper Eocene._ Fresh-water Tortoises.

Bognor. Lower Eocene. Chelone.

Bolney, Sussex. _Wealden._ Hylæosaurus, Iguanodon, Chelonia,

Goniopholis.

Bracklesham Bay. _Middle Eocene._ Crocodiles, Serpents, Chelonians.

Brighton. Chalk. Vertebra of Mosasaurus or Leiodon.

Bristol. _Lias._ Ichthyosaurus.

Brook-Point, Isle of Wight. _Wealden._ Iguanodon, Cetiosaurus, &c.

Burham, near Maidstone. _Chalk._ Chelone, Dolichosaurus,

Pterodactylus.

Bur wash, Sussex. _Wealden_; quarries in the neighbourhood.

Goniopholis, Turtles.

Cambridge. _Lower Chalk._ Raphiosaurus, Polyptychodon. Charmouth.

Lias. Ichthyosaurus.

Charmouth. _Lias._ Ichthyosaurus.

Cheltenham. _Lias._ Ichthyosaurus.

Chipping Norton. _Oolite._ Streptospondylus.

Clayton. _Chalk._ Coniosaurus.

Corncockle Muir, Dumfries. _New Red._ Imprints of feet of Reptiles.

Coton-End, Warwickshire. _New Red._ Labyrinthodon, &c.

Cubbington, Warwickshire. _New Red._ Labyrinthodon.

Cuckfield. _Wealden_; quarries in the vicinity. Iguanodon,

Pelorosaurus, Hylæosaurus, Trionyx, &c.

Culver Cliff, Isle of Wight. _Wealden._ Streptospondylus.

Dover. _Chalk._ Ichthyosaurus, Plesiosaurus.

Garsington, Oxfordshire. _Oolite._ Cetiosaurus.

Glastonbury. _Lias._ Ichthyosaurus.

Grinsill, Warwickshire. _New Red._ Rhynchosaurus.

Guy’s Cliff, Warwick. _New Red._ Labyrinthodon.

Harwich. _London Clay._ Chelonia.

Hastings. _Wealden._ Iguanodon, Pelorosaurus, Goniopholis, Turtles.

Heddington, Oxfordshire. _Kimmeridge Clay._ Pliosaurus.

Hordwell. _Middle Eocene._ Crocodiles, Chelonians, Serpents.

Horsham, Sussex. _Wealden_; quarries in the vicinity. Hylæosaurus,

Iguanodon, Goniopholis, Turtles, &c.

Ilminster. _Upper Lias._ Ichthyosaurus, Teleosaurus.

Kyson, Suffolk. _Eocene._ Serpent, Lizard.

Leamington. _New Red._ Labyrinthodon.

Lewes. _Chalk._ Vertebra; of Mosasaurus or Leiodon.

Lyme Regis. _Lias._ Pterodactyles, Ichthyosauri, and Plesiosauri in

abundance.

Maidstone. _Lower Green Sand_; quarries near the town; particularly

Mr. Bensted’s "_Iguanodon quarry_." Iguanodon, Plesiosaurus,

Polyptychodon, Fresh-water Tortoise.

Malton. _Oolite._ Megalosaurus.

Market Rasen. _Kimmeridge Clay._ Pliosaurus.

Norfolk? _Chalk._ Leiodon: very rare.

Portland, Isle of. _Oolite._ Turtles.

Purbeck, Isle of. _Purbeck._ Goniopholis, Chelonians. _Kim. Clay._

Pliosaurus.

Redland, near Bristol. _Magnesian Conglomerate._ Palæosaurus,

Thecodontosaurus.

Saltwick. _Lias._ Teleosaurus.

Sheppey, Isle of. _London Clay._ Turtles, Serpents, Crocodiles.

Shotover, near Oxford. _Kimmeridge Clay._ Pliosaurus, Teleosaurus.

Southerham. _Chalk._ Mosasaurus, Plesiosaurus.

Stonesfield. _Oolite._ Megalosaurus, Teleosaurus, Pterodactyles.

Stourton, Cheshire. _New Red._ Foot-prints of reptiles

(Cheirotherium), &c.

Street, Somersetshire. _Lias._ Ichthyosauri and Plesiosauri.

Swanage, Isle of Purbeck. Goniopholis, Chelonians.

Tilgate Forest. _Wealden_; quarries in various localities. Iguanodon,

Megalosaurus, Hylæosaurus, Suchosaurus, Turtles, and Tortoises.

Watchett, Somersetshire. _Lias._ Plesiosauri, Ichthyosauri.

Warwick, Guy’s Cliff, near. _New Red._ Labyrinthodon.

Westbrook, Wilts. _Kimmeridge Clay._ Ichthyosaurus.

Weston, near Bath. _Lias._ Plesiosaurus.

Whitby, Yorkshire. _Lias._ Ichthyosauri, Plesiosauri, Teleosaurus.

Wight, Isle of; along the southern shore, near Brook-Point.

_Wealden._ Iguanodon, Cetiosaurus, &c., washed up on the sea-shore.

CHAPTER XVIII.

ORNITHOLITES; OR FOSSIL BIRDS.

Excepting in strata of comparatively modern origin, the remains of

Birds are of extreme rarity in a fossil state. In the caverns that

contain the skeletons of carnivorous animals, and which in many

cases were once their dens, the bones of several species of existing

genera of Birds have been discovered, in England, on the Continent,

in America, and in Australia; and recently there have been obtained

from alluvial deposits in New Zealand the skeletons of Birds, some

of enormous magnitude, and under conditions which leave some doubt

whether, like the _Dodo_, the species may not have been extirpated by

man during the last few centuries; or even if some stray individuals of

the race may not, according to the belief of the aborigines, be still,

in existence in the interior of the country.

From the gypsum quarries at Montmartre, near Paris, Baron Cuvier

obtained several species of Ornitholites; and Prof. Owen has described

the relics of three or four species from the London Clay: these fossil

birds of the eocene tertiary deposits are the most ancient relics

of this class known to the geologist, with the exception of the

foot-prints on the _New Red_ sandstone of North America, that have been

referred to animals of this class.

The rarity of the remains of Birds may probably in some measure

be attributable, as Sir C. Lyell has suggested, to the peculiar

organization of these animals; for their power of flight necessarily

renders them less liable to be engulphed and imbedded in the deltas of

rivers or in the bed of the ocean, than quadrupeds; and the lightness

of their structure, occasioned by their tubular bones and feathery

dermal integument, generally prevents the sinking of the bodies of such

as die on, or fall into, the water; so that their carcases are devoured

or decomposed.

In illustration of this subject, I purpose, in the _first_ place, to

explain such peculiarities in the osteology of the animals of this

class, as may assist the collector in the identification of their

fossil remains; _secondly_, to take a cursory survey of the geological

distribution of fossil Birds, and examine a few of the most interesting

examples; and _lastly_, consider the striking phenomena presented

by the foot-prints of supposed Birds on the strata of those ancient

deposits which are comprised in the _Trias_ or New Red formation.

[Sidenote: OSTEOLOGY OF BIRDS.]

I. Osteological Characters.--The skull in adult birds presents this

remarkable feature, that it is composed of but one bone without any

trace of suture: the osseous tissue is very compact; the bone is

white, and very smooth externally. The lower jaw is formed, as in

reptiles, of several bones, namely, articular, angular, supra-angular,

and dental; it is united to the skull by the intervention of a bone

(_os quadratum_), as in certain reptiles. Both jaws are destitute of

teeth, and are protected by dense horny sheaths, which form powerful

dentary organs. The vertebral column of the neck is exceedingly

flexible, and is composed of a greater number of bones than in any

other living animals; for the cervical vertebæ, which in the mammalia

amount to seven, in birds vary from ten to twenty-four, as in the

Swan. To admit of this extreme mobility of the neck without injury to

the enclosed spinal cord, the annular part, or neural arch, of each

cervical vertebra is enlarged at the extremities that form a junction

with the corresponding bones; thus presenting a modification of

vertebral development directly the reverse of that possessed by the

extinct saurian of the Magnesian conglomerate (see p. 714). The dorsal

and sacra vertebral, on the contrary, are firmly interlocked, and

often anchylosed together, and constitute a strong, inflexible pillar

to afford a fixed point of support to the powerful locomotive organs

of flight. There are no _lumbar_, or rib-less vertebræ. The sacrum

often consists of eighteen, twenty, or more vertebræ, anchylosed into

a solid bone. In the young Ostrich the vertebræ may be found separate

and distinct; and the neural arch is shifted to the union of two

vertebræ, as in the _Megalosaurus_. The sacral spinal cord is almost

as large as the brain; to supply the large muscles. The foramina for

the passage of the nerves are double, one for the sensitive, and the

other for the motive root, which pass out separately and unite in. a

ganglion externally. The ribs are formed so as to combine strength with

lightness in the construction of the walls of the chest, for each rib

has a _recurrent apophysis_, or process, that extends backwards, and

glides over the contiguous bone; this is a very peculiar and obvious

character.[719] The ribs are united in front to the sternum by bony

processes, analogous to the _costal-arcs_ of the Plesiosaurus. The

pectoral arch is distinguished by the prominent longitudinal keel or

crest of the sternum; a structure designed to give attachment to the

powerful pectoral muscles which move the wings, and which presents

characteristic modifications in the different orders; and by the

peculiar bone, termed the _furcula_, or merry-thought, which connects

the clavicles. The clavicles are strongest and most open in birds of

strongest flight. The coracoids (in birds) relate to respiration, and

serve to admit of contraction and expansion of the sternum and abdomen.

The bones of the anterior extremities are modified to adapt these

instruments for the purposes of flight, and those of the fore-arm

(_radius_ and _ulna_) are very long, and firmly united together; the

ulna has a row of slight eminences for the attachment of the quills

of the secondary feathers. The wrist, or _carpus_, is composed of but

two bones, articulated to the radius and ulna, and which admit only

of a _lateral_ movement, by which the wings are folded close to the

body. The bones of the hinder extremities consist of the thigh or

_femur_;[720] the leg-bones, _tibia_[721] and _fibula_, the latter very

small and anchylosed to the former; and of a single shank-bone, which

supplies the place of the tarsal and metatarsal bones of other animals.

This bone is articulated at its upper extremity to the tibia, and

terminates at the lower end in distinct processes, which correspond in

number with the toes; each process having a groove for the pulley-like

tendon that moves the corresponding toe. This construction is peculiar

to birds; for although in some quadrupeds, as the horse for example,

the metatarsus consists of but one piece, the tarsus is composed of

several bones.

[719] In very old crocodiles an analogous apophysis, which is

generally cartilaginous, is sometimes found, ossified (_Owen_).

[720] The acetabulum, or socket for the head of the thigh-bone, is

always perforated. The femur has a surface for the articulation of

the fibula; and by this character the femur of all birds may be

distinguished. There is always a _patella_.

[721] The lower end of the tibia is very like that of the femur.

The toes of birds present deviations equally recognisable; for the

number of the articulations (or _phalangeal_ pieces of bone) in each

toe is different. Thus the thumb, or short toe, has _two_ bones; the

first toe on the inner side _three_; the the middle toe _four_; and

the outer toe _five_. In general, three toes are directed forwards,

and one backwards. In some species, the thumb or opposable toe is

altogether wanting; in others, as in the swallow, it is directed

forwards; in climbing birds, both the outer and the back toe are

situated behind. The position of the hind toe, therefore, affords an

important indication of the habits of the bird (see _Wond._ p. 146,

_Lign. 23_), and from a fragment of the lower extremity of the shank

or tarso-metatarsal bone, with any trace of this articulation, we may

determine whether the individual to which it belonged was a climber,

wader, &c. In the toes of Crocodiles alone, the number of joints is

the same as in birds; but in these reptiles, each toe is supported

by a distinct metatarsal bone. The osteological peculiarities above

enumerated may assist the collector in arriving at some general

inferences as to the nature of any fossil remains of birds.

[Sidenote: FOSSIL BIRDS.]

II. Ornitholites, or Fossil Birds.--The fossil remains of birds consist

in general of their osseous skeletons, and of detached bones, and

rarely of the feathers and eggs.

Pleistocene Epoch.--Bones of the Dodo[722] (see _Wond._ p. 131), a bird

which appears to have become extinct by human agency within the last

two centuries, have been found, associated with the remains of a recent

species of Tortoise, beneath a bed of lava in the Isle of France. And

in some caverns in the island of Rodriguez, the bones of one or more

large birds allied to the Dodo have also been discovered.

[722] See Penny Cyclopædia, _Art._ Dodo, and the beautiful work on the

natural history of the Dodo and its Kindred, by the late lamented Mr.

Strickland and Dr. Melville, 4to.

Dinornis (_fearfully great bird_). _Pict. Atlas_, frontispiece, and p.

172--Numerous bones of large extinct birds have been obtained in New

Zealand by Mr. Rule, the Rev. W. Williams, Col. Wakefield, Mr. Walter

Mantell, and others. These have been referred by Professor Owen to

tridactylous struthious birds (one of which was one-third larger than

the African ostrich), resembling the living _Apteryx_ of New Zealand

(_Wond._ p. 128, _Petrif._ p. 106) in the proportions of the tibia to the

metatarsus, and also in the rudimental state of the wings. The bones

are found in the recent alluvium, but probably in some cases at least

they have been washed by the streams from older alluvial deposits.

An account of the history of the discovery of the gigantic Moa’s bones

in New Zealand (_Wond._ p. 129) is given in full in _Petrif._ p. 93,

_et seq._; and the scientific description of the various parts of

the skeleton of the Dinornis and Palapteryx, chiefly collected from

Professor Owen’s elaborate and finely illustrated memoirs in the

Transactions of the Zoological Society, should be consulted, _Petrif._

p. 108, &c. Of _Dinornis_ Professor Owen discriminates seven or eight

species; of _Palapteryx_, three species; and indications of a species

of a third associated genus, Aptornis.

Fragments of egg-shell accompany these interesting relics of birds

from New Zealand. From Madagascar also bird-bones and eggs have

been obtained in a fossil state, that indicate the original bird

(_Æpyornis_) to have been even of a greater size than the Dinornis.

Ornitholites of the Caverns.--Many limestone districts abound in

fissures and caves, which vary in extent from more superficial hollows

to deep excavations and caverns of considerable magnitude (_Wond._ p.

175, &c.) Beneath the stalagmitic or sparry floors of some of these

caverns, the bones of extinct species of Cats, Bears, and Hyænas, occur

in immense quantities; but the full consideration of these phenomena

will be reserved for the next chapter. The skeletons and detached bones

of several kinds of Birds are often found imbedded with these remains;

and under circumstances which seem to indicate that they were brought

into these caverns as prey by the carnivora, with whose relics they are

now associated. Some examples show that the birds had fallen into the

fissure; others, that their bones had been transported to their present

situation by the action of water.

In the Cave of Kirkdale, in Yorkshire (_Wond._ p. 179), Dr. Buckland

found bones of the Raven, Lark, Pigeon, Duck, and others; and as almost

all the specimens were the remains of wing-bones, it is considered

probable that they are the relics of dead birds, which had been brought

into the cave by the hyænas, whose den it is supposed to have been for

a considerable period (_Reliquiæ Diluvianæ_, p. 34).

Similar remains have been discovered in the Kent’s Hole cavern, and in

that at Berry Head, Torbay; from the latter Professor Owen has obtained

the wing-bones of a Falcon (_Brit. Fos. Mam. and Birds_, p. 558).

In France, the Lunel-Viel caverns have yielded a few bird-bones; and

many such remains occur in the caves of Brazil, described by M. Lund.

The so-called "bone-breccia" of the coasts and islands of the

Mediterranean (_Wond._ p. 185) contains frequent remains of birds: they

have been especially noticed at Cette, Nice, Sardinia, and Gibraltar.

In the deposits especially referred to the northern drift or

Boulder-clay period, fossil birds appear to be very rare, although the

remains of vertebrate terrestrial animals are locally abundant. Dr.

Buckland states that some bones, apparently of a species of goose,

found at Lawford, with the remains of Hyæna, Elephant, Rhinoceros, &c.,

is the only instance he has met with of fossil birds in the drift of

England (_Reliq. Diluv._ p. 27).

On the Continent, bird-bones have been found, at Quedlingbourg,

Meissen, and in the Lahn Valley, in deposits said to be of this age.

Ornitholites of the older Tertiary Deposits. (_Lign. 246._)--The

very rich pliocene deposits at Œningen (p. 559) have afforded a few

fragments of birds’ bones.

Three or four species of Ornitholites (Duck, Heron, Flamingo, &c.),

and several examples of the eggs of birds, have been discovered in

the lacustrine strata of Auvergne. Birds’ bones also occur in the

fresh-water limestone near Issoire, in the Buy de Dôme, associated

with the remains of eocene mammalia. In Germany, bird-bones have been

found in tertiary deposits at Wiesbaden, Wiesnau, and Mornbach. In

the Siwalik Hills the remains of birds are associated with the fossil

reptilia and mammalia, to which reference has already been made (p.

731).

From the quarries of gypseous limestone of Montmartre, near Paris,

Baron Cuvier obtained many bones, and some connected portions of the

skeletons of several birds related to the Pelican, Sea-lark, Curlew,

Woodcock, Owl, Buzzard, and Quail.[723] In several of these examples

there are the imprints and remains of the quills and feathers; in some

the skeleton has perished, and a pellicle of dark-brown substance, with

the configuration of the original, alone remains (see _Lign. 246_).

These Ornitholites are associated with the bones of the Palæotheria,

and other extinct mammalia of the eocene period. Two or three

Ornitholites have been discovered at Montmartre, in which almost the

entire skeleton is preserved. In one example, described by Cuvier,

the remains of a bird are displayed in such a manner as to render it

probable that the animal had fallen on its belly, and become partially

impacted in the surface of the soft gypsum, which is now become solid

stone; and that, previously to its being completely enveloped, the

principal part of its head and the left leg were removed either by

some voracious animal, or by the action of the water. In addition to

the other parts of the skeleton, the under side of the bill is very

distinctly impressed on the stone, and the left branch is entire; there

are also the remains of the cellular basis of the skull; and both the

wings are well preserved. Nine or ten species of fossil birds were

identified by Cuvier from the Paris eocene strata.

[723] Ossemens Fossiles, tom. iii. p. 302, plates lxxii.--lxxv.

[Sidenote: FOSSIL VULTURE.]

[Illustration: Lign. 246. Fossil Bird.

_Eocene._ _Montmartre._

(Cuvier, _Oss. Foss._ vol. iii. p. 318, pl. lxxiii. _fig._ 2.)

The remains of this individual consist only of a thin brown pellicle,

indicating the form and proportions of the head, body, and limbs.]

Lithornis vulturinus. _Geol. Trans._ 2d series, vol. vi. p. 206, pl.

xxi. figs. 5 and 6.--Under the name of Lithornis (_petrified-bird_),

Professor Owen has described the fossil remains of a bird, consisting

of two most characteristic bones,--the sternum and sacrum,--and

fragments of other bones, obtained from the London Clay of the Isle of

Sheppey. These relics present a close agreement with the corresponding

bones of the Vulture tribe, but indicate a smaller species of Vulture

than any now known to exist.

In his "History of British Fossil Mammalia and Birds," 1846, Professor

Owen has also described another sacrum from the Sheppey Clay, a

_sternum_ from Primrose Hill, and the _cranium_ of a bird, probably

of the _Halcyonidæ_ family, from the same eocene deposit at Sheppey.

This has also yielded a portion of shank-bone, which, according to Mr.

Bowerbank, indicates a bird of the size of a full-grown albatross.

Brit. Assoc. 1851.

Some few specimens of cylindrical bones from the Chalk and the

Wealden[724] have been previously referred to Birds, and described

as remains of species of that family. These fossils, however, have

lately been reexamined in comparison with more perfect bones of similar

character; and, with the exception of a few, the structure of which

decidedly has the characters belonging to bird’s bone, the result of

this investigation has assigned them to Pterodactyles.[725] The long

thin cylindrical bones from the Stonesfield Oolite are probably all

Pterodactylian also, as suggested by the late Mr. Miller.

[724] One fragment of a bone, apparently of an _ulna_, retained a row

of small eminences, probably the points of attachment for the quills of

the secondary feathers of the wings. This specimen would appear to have

a decided reference to ornithic structure, but it was transferred to

the British Museum, and is not now to be seen.

[725] See _Quart. Geol. Journ._ vol. ii. p. 96, &c.; and Owen’s

_Monograph on Chalk Reptiles_, 1851, p. 80, _et seq._ It is to be

hoped that the eminent microscopists, Mr. Bowerbank and Professor

Quekett, may be enabled before long to elucidate the intimate structure

of pterodactylian bone; which, although of an essentially reptilian

type, has characters of its own, offering some resemblances to

bird-structure, that have not yet been fully described. Some specimens

of bones from the Wealden (for instance, the specimen figured in

_Geol. Trans._ 2d ser. vol. v. pl. xiii. _fig._ 6, and _Geol. Journ._

vol. iv. pl. i. _fig._ 9,) exhibit under the microscope an intimate

structure resembling that seen in bird-bone, in contradistinction

to that characteristic of reptilian bone. But until we are better

acquainted with the microscopic structure of the osseous tissue of

the Pterosaurians, and are in possession of more perfect specimens of

bones, it cannot be satisfactorily determined to what extent the class

of Birds existed in the country of the Iguanodon.

[Sidenote: ORNITHOIDICHNITES.]

III. Ornithoidichnites. (_Bird-like foot-prints._) _Ligns._ 247, 248.

_Bd._ pl. xxvi. _a_, xxvi._b_.--The palæontological history of the

class of birds, as evidenced by the foregoing pages, is carried back

but to a comparatively recent era in the earth’s history: and indeed,

in the present state of our knowledge, it may be said that all positive

evidence of the former existence of this highly organized class of

vertebrated animals is confined to the Tertiary and Wealden deposits.

A most interesting discovery, however, by Dr. James Deane,[726] of

Greenfield, U. S. seems to prove that numerous bird-like bipeds,

and some of gigantic size, existed at the period when the Triassic

or _New Red_ strata were in the progress of formation; that period,

as the reader will remember, in which the Labyrinthodonts and other

extraordinary reptiles flourished. _Rep. Brit. Assoc._ 1841, p. 230,

note.

[726] See "Illustrations of Fossil Foot-prints of the Valley of the

Connecticut," 1849, 4to. with nine plates.

In certain localities of the New Red sandstone in the valley of the

Connecticut, numerous tridactyle markings had been occasionally

observed on the surfaces of the slabs of stone when split asunder,

in like manner as the ripple-marks appear on the successive layers

of sandstone in Corncockle Muir, Tilgate Forest, &c. Some remarkable

distinct impressions of this kind at Turner’s Falls (Massachusetts)

happening to attract the attention of Dr. Deane, that sagacious

observer was struck with their resemblance to the foot-marks left

on the mud-banks of the adjacent river by the aquatic birds which

had recently frequented the spot. The conviction that the imprints

on the stone were referable to a similar origin with those on the

mud was so strongly impressed on his mind, that he immediately

collected a series of specimens, and communicated his discovery and

opinion to Professor E. Hitchcock, who followed up the inquiry with

a zeal and success that have led to the most interesting results.

No reasonable doubt now exists that the imprints in question have

been produced by the tracks of bipeds, impressed on the stone when

in a soft state. The announcement of this extraordinary phenomenon

was first made by Professor Hitchcock, in the American Journal of

Science (January, 1836); and that eminent geologist has subsequently

published full descriptions of the different species of imprints

which he has detected, with excellent lithographs, in his "Geology of

Massachusetts." (See _Petrif._ pp. 64-73.)

Three highly interesting specimens of the Ornithoidichnites of North

America, collected and developed by Dr. James Deane, have been lately

added to the collection of organic remains in the British Museum. They

exhibit several varieties of the foot-prints, and are in a very fine

state of preservation. The surface of the largest slab is eight feet

by six, and bears upwards of seventy distinct impressions, disposed

in several tracks, as shown in the _Lign. 247_. The direction and

disposition of the foot-tracks are rendered more distinct by the lines

drawn from one imprint to another in the consecutive series.

The principal tracks on this slab, _Lign. 247_, are as follow;

Fig. 1 to 1, directed from below upwards, is a track consisting of six

large footsteps.

2 to 2, from above downwards; a track of four foot-prints, disposed

almost in a right line, and very far apart.

3 to 3, a track of five foot-prints, from above downwards, of a

large, heavy animal, like fig. 1.

4 to 4, from above downwards, four foot-prints like _fig._ 2,

disposed in a nearly straight track, and far apart.

5, a track of five heavy foot-prints, directed obliquely

upwards.

6 to 6, five foot-prints of a large biped, in a track from below

upwards.

7, a series of five delicate foot-prints.

8 to 8, a track of eleven very small foot-prints, disposed in

zigzag, and extending obliquely from the right extremity

to the upper edge of the slab.

9 to 9, a track of four large and distant foot-prints, passing

obliquely across the stone from left to right.

I subjoin also a representation of one of the smaller foot-prints, of

the natural size, the surface of the stone being sprinkled also with

hemispherical markings produced by drops of rain. (_Lign. 248._)

A Slab of New Red Sandstone (_eight feet by six_), from Turner’s Falls,

Massachusetts, United States, covered with numerous Foot-marks of

Bipeds; indicating the Tracks of ten or twelve individuals, of various

sizes. Discovered by _Dr. James Deane_, of Greenfield, Massachusetts.

This Specimen is now in the British Museum.--(_From the American

Journal of Science_, vol. xlvi. p. 73.)

[Illustration: Lign. 247. Ornithoidichnites, or Imprints of the

Footsteps of Bipeds with Bird-like Feet, on Sandstone.

_To face_ p. 770.]

[Sidenote: ORNITHOIDICHNITES.]

The above will suffice to give the reader a general idea of the nature

of these extraordinary impressions. A few shapeless fragments of

bones are the only vestiges of the skeletons of any animals, with the

exception of fishes, that have been found in the strata which have

furnished the slabs of Ornithoidichnites. Some Coprolites also have

been discovered.

[Illustration: Lign. 248. Bird-like Footprint, and impressions of

Rain-drops, on Sandstone (_nat._). _New Red Formation; Massachusetts._

[Amer. Journ. of Science, (1843,) vol. xlvi. p. 73.]]

The enormous size of some of the foot-marks is calculated to excite

great surprise. I have in my possession (through the kindness of Dr.

Deane) imprints that prove the size of the foot to have been fifteen

inches in length, and ten inches in width, exclusive of the hind

claw, which is present in some species, and is here two inches long.

The foot-prints of this biped when in a consecutive series of five

or six, are from four to six feet apart; which, of course, must have

been the length of the stride; the longest stride was probably made

by the animal when running; the shortest, when walking at a moderate

pace. These footsteps indicate proportions so far exceeding those

of all known living bipeds,--for the foot of the African ostrich is

but ten inches long,--that the geologist may be pardoned for having

hesitated to adopt the opinions of the American savans, in the absence

of any relics of the osseous structure of the supposed birds; although

sanctioned by the high authority of Dr. Buckland, who, from the first,

concurred in the views of Professor Hitchcock (_Bd._ ii. p. 39): but

this objection has been in a great measure removed by the discovery of

the remains of the gigantic Moa or Dinornis of New Zealand, with feet

equal in magnitude to the largest of the Connecticut foot-prints. See

p. 763, and _Pict. Atlas_, frontispiece. Professor Hitchcock is of

opinion that upwards of forty species of these biped foot-prints may be

distinguished. Foot-prints referable to chelonians, batrachians, and

lizards are associated with the above.[727]

[727] Trans. Amer. Phil. Soc. n. s. vol. x. pt. ii. p. 312.

In the New Red Sandstone of Stourton Hill, near Liverpool, Mr.

Cunningham has observed tridactylous, webbed foot-prints,[728] 2-1/2

inches long, which he refers to a bird; Mr. Hawkshaw also noticed

some bird-like tracks at Lymm; and Professor Harkness met with a trace

of a biped at Weston Point, near Runcorn. These appear to be the only

indications of ornithoidichnites in the Trias of England; and these are

very obscure.

[728] These are accompanied by cheirotherian prints, and by the

cast of an impression quite similar to that made on the sands of the

sea-beach of to day, by the Medusa (sea-nettle or jelly-fish) left by

the reflux of the tide and exposed to a few hours of sunshine. Mr.

Cunningham and Mr. Pidgeon have furnished a figure of this interesting

impression of the "jelly-fish," which has left "the solid memorial of

its evanescent existence en the ancient strand" of the Triassic sea,

showing that the physical conditions of land, water, and atmosphere

were the same then as those that now obtain.--_Liverpool Lit. Phil.

Soc. Proc._ 1848, p. 128, _fig._ 1. A similar imprint on a Jurassic

rock in Germany is referred to at p. 280.

In the Wealden of Hastings and the Isle of Wight, the natural casts of

large tridactylous foot-prints have been observed by Mr. Taggart and

Mr. Beckles (see _Quart. Journ. Geol. Soc._ vol. ii. p. 267, vol. vii.

p. 117, vol. viii. p. 396, and _Geol. Isle of Wight_, p. 328), but as

yet no solution of the mystery at present enwrapping these gigantic,

tridactylous, biped (?) ichnolites has presented itself: we only know

that the creature that left them traversed the borders of the mighty

river which floated down the bulky carcases of the Hylæosaur and

Iguanodon.

[Sidenote: ON COLLECTING FOSSIL BIRDS.]

On Collecting the Fossil Remains of Birds.--Notwithstanding the extreme

rarity of fossils of this class, the student should not be discouraged

in his search for the remains of Birds in the secondary rocks. That

far more instructive specimens than any that have fallen under my

observation may be discovered in the Wealden strata by diligent

research, there can be no reasonable doubt. It is also very probable

that the Stonesfield slate, which abounds in remains of terrestrial

plants and animals, will be found to contain Ornitholites. It is

important for the collector to bear in mind, that when only a fragment

of the shaft of a bone remains imbedded in the stone, if the imprint

of the other portions be preserved, he may obtain a knowledge of the

form of the extremities; in the same manner as the external markings

of the surface of a shell may be ascertained, when the shell itself is

lost or destroyed, and a smooth stony cast of the internal cavity only

is left. The same remark will apply to the bones of reptiles and other

animals; for example, a perfect leg-bone may be imbedded in a block of

limestone; but, when exposed by breaking the stone, a portion of the

shaft may alone remain attached, and both extremities be shattered to

pieces by the concussion of the blow; yet, if the impression remains,

the entire form of the original may be determined.

The _foot-prints_, not only of birds, but of reptiles and other animals,

should be diligently sought for on the surfaces of laminated strata of

sand and clay, and especially where the presence of ripple-marks, and

the impressions of rain-drops, indicate that the beds were deposited in

shallow water. The forest-marble flags at Castle Comb, north of Bath,

the Stonesfield slates, and the sandstones around Horsham (in Sussex),

and particularly at Stammerham (see _Geol. S. E._ p. 213), are often

rippled, and it is therefore probable that the foot-prints of some of

the Oolitic and Wealden quadrupeds and bipeds, if such existed, will

sooner or later be discovered.

CHAPTER XIX.

FOSSIL MAMMALIA.

The remains of Mammalia discovered in a fossil state include an immense

number of species, and furnish examples of almost every living genus,

and of numerous genera, and even orders, of which no existing species

are known. Yet amidst the vast accumulations of the skeletons of the

higher orders of vertebrata contained in the tertiary deposits, and in

the superficial drift, belonging to species which have successively

appeared on the surface of our planet, flourished for indefinite

periods of time, and then become annihilated, no vestiges of Man, or

of his works, have been detected. Human skeletons, naturally imbedded,

have hitherto only been observed in the silt of modern alluvial

plains,[729] in peat-bogs (_Wond._ p. 64), and in conglomerates

of recent date, such as are in the progress of formation on the

sea-shores, particularly where the water is loaded with the detritus of

shells and corals, and the waves transport the calcareous matter along

the margins of creeks and bays, or deposit it in the shallows along the

coast (see _Wond._ p. 87, and _Petrif._ p. 483).

[729] There seems, however, reason to believe that the human skulls

and bones found with elephantine and other remains in the Alps of

Swabia, are of contemporaneous origin with these extinct mammals. (See

_Literary Gazette_, 1853, p. 1027.)

The geological distribution of fossil mammalia,[730]--the occurrence of

the entire carcases of extinct species of Elephant and Rhinoceros in

blocks of ice (_Wond._ p. 151),--of recent species in the superficial

alluvial clay and silt,--of recent and extinct forms in the Drift or

Pleistocene deposits (_Wond._ p. 147),--of the gradual preponderance

of unknown species and genera, in proportion as we carry back our

retrospect to the most ancient Tertiary strata (_Wond._ p. 254),

--the sudden disappearance of all vestiges of the entire Class of

Mammalia, with the last bed of the Eocene deposits,--with the exception

of a few minute jaws in one set of beds of the Oolite in England

(_Wond._ p. 510), and of a few teeth in the Trias (?) of Germany,[731]

the sole records of the existence of any of the highest types of

animal organization throughout the vast periods of the secondary

formations--are so fully treated of in the _Wonders of Geology_, that I

need not dwell upon the subject in the present volumes. Neither is it

desirable to enter at large upon this department of Palæontology, for

it were vain to attempt the elucidation of the anatomical characters

of but one extinct species of Mammalia, without giving details of

structure, that could only be successfully demonstrated in a work

expressly devoted to the subject. Referring, therefore, to Cuvier’s

_Ossemens Fossiles_, and to Professor Owen’s "_History of the British

Fossil Mammalia_," 8vo. 1846, I must limit my remarks on the Fossil

Mammalia to a brief summary of modern discoveries, with suggestions for

the identification and collection of some of the most interesting or

prevalent remains.

[730] For a notice of the distribution of mammalian remains in the

Upper Tertiaries of Europe, see Phillips’s _Geology_, 1853, vol. i. p.

45, &c.

[731] For an account of these teeth of small insectivorous mammals from

the "bone-bed" of Würtemberg, which has an analogous position at the

top of the Trias with the "bone-bed" of Axmouth and Aust Cliff, see

_Ly._ p. xiv. figs. 529-531.

The fossil remains of Mammalia will be considered under the following

heads:--

I. Cetacea, or animals of the _Whale tribe_.

II. Ruminantia; including the _Camel_, _Giraffe_, _Deer_,

_Sheep_, _Ox_, &c.

III. Pachydermata; comprising the _Proboscideans_, as the

_Elephant_, and the ordinary _Pachyderms_, as the

_Rhinoceros_, _Horse_, _Swine_, &c.

IV. Edentata: animals without teeth, or with only

molars, as the _Ant-eater_, _Sloth_, _Megatherium_, _Mylodon_,

&c.

V. Rodentia, or Gnawers; as the _Hare_, _Beaver_, _Rat_, &c.

VI. Marsupialia; animals with an abdominal pouch, as

the _Kangaroo_, _Opossum_, &c.

VII. Carnivora; including the _Bats_, _Moles_, and the carnivorous

tribes in general.

VIII. Quadrumana; _Apes_ and _Monkeys_.

IX. Bimana; or _Man_.

[Sidenote: FOSSIL WHALES.]