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MONS (Natio We:
A MONOGRAPH

ON THE

FOSSIL REPTILIA

THE CRETACEOUS FORMATIONS,”

BY

PROFESSOR OWEN, D.C.L., F.RS., F.LS., F.GS., &.

LONDON:
PRINTED FOR THE PALHONTOGRAPHICAL SOCIETY.

1851—1864.

The Monograph on ‘Tue RepriLia oF THE CRETACEOUS FoRMATIONS’ was published as follows :

Part I, pages 1—118; plates I—XXXVII, with VIIa and IXa, June, 1851.
Supplement I, pages 1—19 ; plates I—IV, November, 1859.

Supplement II, pages 27—30; plate VII, March, 1861.

Supplement III, pages 1—25; plates I—VI, March, 1861.

Supplement IV, pages 1—18; plates I—IX, August, 1864.

CONTENTS

OF THE

MONOGRAPH ON THE REPTILIA OF THE
CRETACEOUS FORMATIONS.

OrpER—CHELONIA. Family—Martna.

Chelone, observations on genus : : Part I. Page 1
Chelone Benstedi 5 ‘ ee Fri A
3 pulchriceps 3 : ¢ 5p 8
i Camperi d y : ‘ 9
Chelones indeterminate . : : ie 11

Family—Patupinosa.

Protemys, new genus : : . 3 15
Protemys serrata i 4 i 2 Me
Orver—LACERTILIA. Tribe—Repentia.

Raphiosaurus, observations on genus. 5 5 Ng
Coniosaurus, observations on genus F ; ie 21
Coniosaurus crassidens ‘ : ‘ i

Dolichosaurus, observations on genus . § a 22
Dolichosaurus longicollis . . . 2» »

Tribe — Nartanmta.

Mosasaurus, observations on genus ‘ : of 29
Mosasaurus gracilis : 9 0 a 31
Leiodon, observations on genus : i 5 Al
Leiodon anceps . , : 0 ms 42

Orper—CROCODILIA.

Crocodilus (?), observations on a specimen from the Greensand

of Sussex . H : j hi 45
Orper—ENALIOSAURIA.
Polyptychodon, remarks on genus : ; es 46
Polyptychodon continuus . : bp 47
Remarks on a gigantic fossil Saurian fon Hythe . 5 yi
Polyptychodon interruptus . é , $5 55

Plesiosaurus, remarks on genus : . - 58

il CONTENTS.

Plesiosaurus Bernardi

55 constrictus

oD pachyomus
Plesiosauroid paddle
Ichthyosaurus, remarks on genus
Ichthyosaurus campylodon

ah i teeth of
a 55 jaws of
5 53 vertebree of .

Orxpur—PTEROSAURIA.
* Pterodactylus, remarks on genus
Pterodactylus Cuvieri
5 giganteus :
in s scapular arch of
eS compressirostris
Long bones of Pterodactylus Cuvieri
$5 a compressirostris
Orper—DINOSAURIA.
Iguanodon, remarks on genus ¢ :
5 dorsal and caudal vertebre, clavicle, &c.
on teeth

Orper—PTEROSAURIA.
Pterodactylus, specimens of genus
Pterodactylus Sedgwickii

e Fittoni

a (sp. inc.) teeth .

3” ” vertebree

39 5 sacrum :
55 ; caudal vertebree
3 2D frontal bone (?)
2 x scapular arch .
” BS humerus

” 3 wing-metacarpal

Orper—DINOSAURIA.
Tguanodon, dentition of the upper and lower jaws of

Orver—PTEROSAURIA.
Pterodactylus, additional remarks on genus
Pterodactylus simus ;
33 Woodwardi .
6 (sp. inc.) mandible
; 3 basi-occipital

Part I. Page 60

Sup. II.

Sup. IT.

61
64.
66
68

CONTENTS. iii

Pterodactylus (sp. inc.) atlas and axis : Sup. III. Page 6
A 4y cervical vertebre bs 7
3 3 caudal vertebree : A 8
mI * sternum 6 F of IL
bp a humerus : ; ies 13
3 es carpal bones rf ae 17
Bs % ungual phalanx : oS 19
Orper—SAUROPTERYGIA.*
Polyplychodon interruptus . : ; Pi 20
x oh cranium and teeth . 55 3
33 BG cervical vertebre ay 22
33 5 atlas and axis a 24.
Plesiosaurus planus : : : Sup: IV). 2
33 » vertebral centrum Hh <
Plesiosaurus Bernardi “ 7
55 FI cervical vertebra FS ¥
Plesiosaurus neocomiensis . : : Py 11
3 3 cervical vertebre “ a
Plesiosaurus latispinus ‘ 6 : Ke 14
a - cervical and dorsal vertebree Pe 4
a is ilium and coracoid Bs Es

* The Enaliosauria of Conybeare were divided into two orders, ‘Sauropterygia’ and ‘ Ichthyopte-
rygia,’ in a “ Memoir on the Classification of Recent and Fossil Reptilia,” in the ‘ Reports of the British
Association,’ 1859, on the grounds therein assigned, pp. 159, 160.

er eae

+ Has

INDEX

TO THE

i SPECIES DESCRIBED IN THE MONOGRAPH

ON THE

REPTILIA OF THE CRETACEOUS FORMATIONS.

Chelone Benstedi, Owen, Lower Chalk. Part I, p. 4, tabs. 1, 1, 111.

» Camperi, Owen (?), Upper Chalk. Part I, p. 9, tab. v.

» pulchriceps, Owen, Upper Greensand. Part I, p. 8, tab. viia, figs. 1, 2, 3.
Chelones indeterminate, U.C.—L.C. Part I, p. 11, tabs. vii, via, figs. 410; tab. xxix.
Coniosaurus crassidens, Owen, U. C—L. C. Part I, p. 21, tab. ix, figs. 13, 14, 15.
Crocodilus (?), sp., L. G. S. Part I, p. 45, tab. xv.

Dolichosaurus longicollis, Owen, L. C. Part I, p. 22, tab. x, figs. 1, 2, 3, 4.

Emys Benstedi, Mant., L. C. Part I, p. 4, tabs. i, ii, iii.

Ichthyosaurus campylodon, Carter, L. C—U.G. Part I, p. 69, tab. iv, figs. 1—10, 18—
16; tabs. xxii, xxiii, xxv, xxvi.

Iguanodon Mantelli, Meyer, L. C.—L.G.S. Part I, p. 105, tabs. xxxiti—xxxvu; Sup. II,
p- 27, tab. vii.*

Leiodon anceps, Owen, U. C. Part I, p. 42, tab. ix a.

Mosasaurus gracilis, Owen, U. C. Part I, p. 31, tab. viii, figs. 1, 2, 3; tab. ix, figs. 1—5;
tab. ix, fig. 9.

Plesiosaurus Bernardi, Owen, U.C.—U.G. Part I, p. 60, tab. ix, figs. 8, 9; tab. xviii;
Sup. IV, p. 7, tab. iv.

Plesiosaurus constrictus, Owen, U.C. Part I, p. 61, tab. ix, figs. 6, 7.

% latispinus, Owen, L.G. Sup. IV, p. 14, tabs. vii, viii, ix.
a6 pachyomus, Owen, U. G. Part I, p. 64, tabs. xx, xxi.

5 planus, Owen, U. G. Sup. IV, p. 2, tabs. i, ii, iii.

oy neocomiensis, Campiche, U. G. Sup. IV, p. 11, tab. vi.
Pe sp., L. C. Part I, p. 63, tab. xix; p. 66, tab. xvii.

Py SplieG.) Partly p. 62) tab) xx. fies: 75.9.

Pterodactylus compressirostris, Owen, L. C. Part I, pp. 95, 98, tabs, xxiv, xxvii, fig. 5;
tab. xxviii, figs. 8—10; tab. xxx, figs. 4, 5*.

Pterodactylus Cuvieri, Bowerbank, L.C. Part I, pp. 88, 97, tab. xxviii, figs. 1—7; tab. xxx,
figs, 1—3*,

* For additional remarks on the Iguanodon, see ‘ Monograph on the Wealden Reptilia.’

vi INDEX.

Pterodactylus Fittoni, Owen, Up. Greensand. Sup. I, p. 4, tab. 1, figs. 3, 4, 5.

giganteus, Bowerbank, L. C. Part I, p. 91, tab. xxxi.
35 Sedgwickii, Owen, U. G. Sup. I, p. 2, tab. i, figs. 1, 2, 6, 7; tabs. i, i,
tab. iv.
Pterodactylus simus, Owen, U. G. Sup. III, p. 2, tab. i, figs. 1—5.
ue Woodwardi, Owen, U.G. Sup. III, p. 4, tab. 1, figs. 6—16; tab. ii, figs.
1h TO,
Polyptychodon continuus, Owen, C.—L. G.S. _ p. 47, tab. xiv, figs. 4, 5, 6.
o continuus (?), L. G. 8. Part I, p. 47, tabs. xii, xiii.
. interruptus, Owen, M. C.—U.G. Part I, p. 55, tab. x, figs. 7, 8, 9; tabs.

xl, xiv, figs. 1, 2; Sup. III, p. 20, tab. iv, figs. 1—s.
Protemys serrata, Owen, L. G. S. Part I, p. 15, tab. vii.
Raphiosaurus subulidens, Owen, L. C. Part I, p. 19, tab. x, figs. 5 and 6.
53 Sty Wo (5 jo HO:

MONOGRAPH

ON

THE FOSSIL REPTILIA

OF THE

CRETACEOUS FORMATIONS.

BACB Dk.

Paces 1—118; Puates I—XXXVII, with VIIa and IXa.

CHELONIA (Uacertitia, &c.).

BY

PROFESSOR OWEN, D.C.L., F.RS., F.LS., F.GS., &c.

Issued in the Volume for the Year 1851.

LONDON :
PRINTED FOR THE PALZONTOGRAPHICAL SOCIETY.
1851.

MONOGRAPH

ON

THE FOSSIL REPTILIA

OF

THE CRETACEOUS FORMATIONS. |

OrpER—CHELONTA.
Genus, CHELONE, (Turtles.)

One of the earliest, if not the first, indication of the occurrence of fossil
Turtles in the formations of the Cretaceous Period, is given by the celebrated
anatomist CAMPER, in a ‘Memoir on the Petrifactions found in St. Peter’s Mount,
Maestricht,’* where, referring to some specimens which he had procured for the
British Museum, he writes :—“ Another very beautiful specimen, a foot and a half
long, and about ten inches broad, I have been induced to add, because it contains the
anterior part of the scutum of a very large Turtle. Of this Mr. Joon HUNTER has
an analogous bone from the same mountain in his valuable collection, but sent to him
under another name. I am convinced it belonged formerly to a Turtle ;—first, because
I have from the same mountain the entire back of a Turtle, four feet long and sixteen
imches broad, a, little damaged at the sides, and a pretty large fragment of another
Turtle in my possession: secondly, because I have a similar one, but so placed
within the matrix, as to show the inside of that piece in the back of a large Turtle I
got in London, by the favour of Mr. SHELDON: thirdly, because I have amongst these
bones the lower jaw-bone of a very large Turtle, of which the crura, though not
entire, are seven inches long, and distant from one another six inches; the thickness
is equal to one inch and a quarter.’ In a collection of engravings belonging to my

* Philosophical Transactions, 1786. + Thbid., p. 450.

2 FOSSIL REPTILIA OF THE

late father-in-law, WILLIAM CuFt, Esq., F.R.S., there is one of a carapace of a large
fossil Turtle, corresponding in size with that mentioned by Camper, and in his style
of drawing. It is entitled “Tortue petrifice trouvée dans la Montagne de St. Pierre
pres de Maestricht;’ and exhibits the “nuchal” and anterior “marginal” plates;
ten “neural” plates, of a rhomboidal figure, carinated, and of nearly equal size, the
fifth being six inches in diameter: the eight costal plates of the left side, and the first
two and last three of those on the right side. The length of the first costal plate is
seven inches, that of the last is little more than three inches; remains of the long and
slender ribs are shown extending from the apices of the costal plates, which, in
proportion to the length of the entire carapace, and to their own antero-posterior
diameter, which is five inches, are extremely short, for in a carapace of a Turtle four
feet in length, the costal plates must be supposed to have attained their full extent of
ossification. The transverse diameter of the neural plates in this large fossil Turtle
from Maestricht is three fourths that of the costal plates at the fore-part of the
carapace, and is greater than that of the costal plates at the hind part,—a proportion
which I have not noticed in any other Turtle, recent or fossil. 'The same characters
appear in the figures given by M. Faujas St. Fond, of the same large species of Turtle.*
CuviER, whose superior anatomical knowledge enabled him to correct some erroneous
remarks which M. Faujas St. Fond had published respecting the Chelonian remains in
his ‘ History of the Fossils of St. Peter’s Mount, arrives at the conclusion, that they
belonged to the Turtles, or marine genus Chelone, and to a species distinct from any
existing Turtle ;+ but he does not notice the character of the great breadth of the
neural plates, as compared with that of the costal ones; he only remarks that the great
Maestricht Turtle appears to have much resembled the Chelone caretta.

The formation, near Maestricht, in which these Chelonian fossils occur, is the most
recent member of the deposits of the Secondary epoch,—the highest and last formed
of the cretaceous group: it consists of a soft yellowish stone, not very unlike chalk,
and includes “siliceous masses, which are much more rare than those of the chalk, of
greater bulk, and not composed of black flint, but of chert and calcedony.t{

Fossil remains of the Chelonian Order were deemed to be of rarer occurrence in
the Chalk formations of England, which are apparently of older date than those at
Maestricht. The first intimation of such was given by Dr. Buckland, in his ‘ Bridge-
water Treatise’ (1836), vol. ii, p. 67, pl. 44’, fig. 3d, which is described as a “ beak of a
small testudo from chalk, in the collection of Mr. Mantell, showing a fibro-cancellated
bony structure, very different from the compact shelly condition of the Rhyncolite, for
which it may, from its size and shape, be mistaken.” Dr. Mantell states, in his
‘Wonders of Geology’ (1839), vol. i, p. 330, that this specimen is “ from the Lewes

* Histoire Naturelle de la Montagne de Saint-Pierre de Maestricht, 4to, 1800, pl. xii-xiv.
+ Ossemens Fossiles, 4to ed. 1824, tom. v, pt. 2, p. 242.
t Fitton; Proceedings of Geol. Soc., 1830.

CRETACEOUS FORMATIONS. 3

chalk,” and probably, therefore, from the Lower Chalk. Further evidence of the
remains of Chelonia in the cretaceous deposit is given in my paper on that subject read
before the Geological Society, April 29, 1840, and published in vol. VI, p. 411, of the
Second Series of the ‘Geological Transactions.’ - The Chelonite there described and
figured was obtained from the Lower Chalk at Burham, in Kent, and consisted of
four marginal plates of the carapace, and a few other obscure fragments, sufficient to
prove that the species was not of a Zrionyx or Testudo ; and as they differed in form
from those of the recent species of Chelone, with which I compared them, and
resembled rather the posterior marginal plates of some Emydians, I stated that this
correspondence “rendered it probable that these remains are referable to that family
of Chelonia which live in fresh water or estuaries.” Subsequent observation of the
various interesting modifications by which extinct Chelones diminish, as it were, the
gap between the marine and fresh-water genera as they remain at the present day,
weakened the impression which the character of the marginal plates of the chalk
Chelonite first made in favour of its Emydian affinities; and the examination of the
beautiful Chelonite, obtained from the same quarries at Burham, in Kent, and relieved
from the chalk matrix by Mr. Bensted, described and figured by Dr. Mantell in the
‘Philosophical Transactions’ for 1841, demonstrated that it is not an Hmys but a true
Chelone, as I have stated in the note appended to my paper in the ‘Geological
Transactions.’

As one of the figures in Dr. Mantell’s Memoir, Pl. 12, fig. 2, exhibits the extra-
ordinary character of ten pairs of ribs in the carapace of this rare fossil, permission
was obtained for original drawings to be made from the specimen, and these form
the subjects of T. I-and T. II of the present Monograph.

From the time of CaLpzEs1,* the constancy of the number of pairs of ribs
which enter into the formation of the carapace of the Chelonian Reptiles has been
confirmed by all subsequent observations. No anatomical fact, perhaps, is better
determined, and more plainly and positively laid down, in all handbooks of Comparative
Anatomy. Perhaps no monstrosity would sooner arrest the attention, or excite more
wonder in the Comparative Anatomist, than the appearance in a recent or fossil
Chelonian of a greater number of pairs of ribs in the carapace than 8. When, there-
fore, I saw the figure 2 of Plate XII of the volume of the ‘ Philosophical Trans-
actions’ for the year 1841, exhibiting not fewer than 10 expanded ribs on the left or
entire side of the fossil carapace, and 9 expanded ribs on the mutilated right side of
the same carapace, and found the experienced and well-known author appealingyt to

* Osservazioni anatomiche intorno alle Tortarughe maritime d’Acque dolce et Terrestre ; 4to, 1687.

+ Dr. Mantell’s words are—“The inner surface of the carapace is also thus displayed (Pl. 12, fig. 2),
together with the mode of union and growth of the costal processes, and the attachment of their distal
extremities to the osseous border. The accuracy of the drawings renders any detailed description un-
necessary.’’—Phil. Trans., 1841, p. 156.

4A: FOSSIL REPTILIA OF THE

the accuracy of the drawings as an excuse for omitting any detailed description of the
rare fossil, I was at first inclined to infer the existence of an extraordinary anomaly in
the construction of this extinct Chelonian of the Cretaceous period; but, having more
pleasure in the contemplation of the harmonies and constants of Nature than her
wonders, it was with no regret that I found that the error or lusus lay with her
illustrator, and not with his subject, as I have ascertained by a careful inspection of
the original. The artist has supplied the additional ribs from his imagination; and in
the view, in fact, in which his attention was kept more closely to the parts, as in that
of the upper surface of the same carapace (PI. XI, Phil. Trans., 1841), he gives the
true number of 8 pairs of carapacial ribs or costal plates; and the author, in refer-
ence to the characters of the carapace “as shown in plate XI,” states, that “it is
composed of eight ribs on each side the dorsal ridge.” The correct view of the
under surface of the carapace is given in T. II, fie. 1 of the present Monograph.

CHELONE BENsTEDI, Owen. T. I, II, and III.

Syn. Emys Brnsrrep1, Mantell, Philosophical Transactions, 1841,
CurLone BunstepI, Owen. Report of British Fossil Reptiles, in ‘ Reports of the British
Association,’ 1841, p. 173.

The fossil in question consists of nearly the whole carapace (T. 1), and a
considerable portion of the plastron (T. II, fig. 2), with a coracoid bone (T. II,
fig. 2, 52, 53).

The carapace includes all the neural plates; the usual number, viz., eight pairs
of costal plates (p/.1—8,T.1); and the entire border of marginal plates, save the
nuchal and two or three succeeding ones. In the plastron (T. IJ, fig. 2), the
hyosternal (4s) and hyposternal (ps) bones may be distinguished. The general form
of the carapace is elliptical, terminated by a point at the narrower posterior end,
which, however, is less contracted than in some other Chelones. It is as depressed as
in Chelones generally, as is shown in the side view T. I, fig. 2. To judge from the
unmutilated and exposed neural plates, which are the first, the second, and the sixth
to the tenth inclusive, the carapace appears to have been traversed by a median longi-
tudinal crest, from which the sides gently slope with a slight convex curvature, as in
Chelone mydas.

The more immediate indications of the close affinity of the fossil to the marine
Turtles, are given by the incomplete ossification of the costal plates and of the
elements of the plastron; the latter bemg in consequence dislocated from each other ;
and more especially by the shape and size of the marginal plates (T. I, fig. 1, 6, 7, 8, 9)
attached to the third, fourth, fifth, and sixth ribs; as also by the form and length of
the coracoid bone.

CRETACEOUS FORMATIONS. 5

The neural plates are as narrow relatively as in the ordinary Chelones, and differ in
this respect from the broad rhomboidal plates in the Chelone Camperi of Maestricht.
The first and second are long and narrow, with almost parallel sides; they are carinate
above, and the first is crossed by the indentation of the juncture between the first and
second vertebral scutes. The third and fifth are similarly indented. The eighth,
which is the smallest of the neural plates, is crossed near its anterior border, by the
impression of the juncture between the fourth and fifth vertebral scutes; this neural
plate is 3 lines in length and 2 in breadth:* the ninth expands posteriorly into a
triangular form; both these have their middle part raised into a ridge: the tenth
plate is suddenly expanded, with angular sides, which slope away from a median
longitudmal ridge: this is crossed by a transverse impression just anterior to its
junction with the pygal or median terminal plate (py) of the marginal series, which is
convex above and traversed by a median longitudinal furrow. The margins of this
plate meet posteriorly at an open angle. The second to the seventh pairs of costal
plates extend along the upper part of only the vertebral halves of the ribs, of which
they appear to be expansions. The length of such expanded part of the third rib
(pl. 3) is 9 lines; its narrow, tooth-like part, before it reaches the marginal plate, is
9 lines; about 3 lines of its extremity is inserted into the deep groove of the concave
surface of the sixth marginal plate, m6. The width of the interspace between the
narrow parts of the third and fourth ribs is 4 lines; the length of the expanded part
of the first rib is 105 lines; the breadth of the expanded part of the first rib is 8 lines ;
the length of the narrow end of the rib, clear of the marginal plate, is 3 lines. In the
superior breadth of the first rib, the Chelone Benstedi agrees with existing turtles, and
differs strikingly from the Purbeck species. The last short rib (pi. 8) sends almost
directly backwards a short, narrow, tooth-like process, at right angles to the anterior
margin of its sub-triangular expanded part. In Chelone obovata it is extended more
nearly parallel with the expanded part.

The marginal plates (m4 to py) have the same general uniformity of size which we
observe in the existing Chelones (see the Cuts 1 and 2, p. 3, of the ‘ Monograph on the
Reptiles of the London Clay’); the posterior ones are not expanded as in the Purbeck
Chelone, and in certain Hmydes, as mys serrata, &c.; but the most decisive evidence
against the Emydian affinities of the present fossil is afforded by the form and develop-
ment of the inferior borders of the marginal plates attached to the fourth, fifth, and
sixth ribs (m7, m8, and m9, T. I, I, fig. 1); for these plates, instead of being expanded
and extended inwards to join the hyo- and hyposternals and to combine with these
elements of the plastron in forming the lateral supporting wall of the carapace, are
not so much developed in breadth as the same parts of the posterior marginal plates,
but form with them an even free border, as in other Chelones, in which not any of the

* In all Hmydes the proportions of this plate, when it is not suppressed, are the reverse of those
in the fossil.

6 FOSSIL REPTILIA OF THE

marginal plates are joined with the sternum. This unmistakeable evidence of the marine
character of Mr. Bensted’s beautiful fossil is unequivocally shown at 4, in Pl. 12, fig. 2)
of the ‘Philosophical Transactions’ for 1841, in which, nevertheless, the fossil is
referred to the genus Hmys.

With reference to the general imperfect ossification of the carapace, the deductions
in favour of the marine nature of the Chalk Chelonite might be invalidated by the
hypothesis, that it was the young of some very large species of Hmys ; but the existing
Emydians at the immature period when they exhibit the incomplete ossification of the
carapace and plastron, have the marginal plates opposite the lateral processes of the
hyosternals and hyposternals joined with those processes by an inward development of
their inferior border, which is suddenly and considerably broader than the inferior
border of the contiguous free marginal plates.

The outer contour. of the tenth, eleventh, and twelfth plates of the Chelone
Benstedi, projects in the form of a slight angle, and they thus differ from the same
parts of Chelone mydas and Chelone obovata ; most of the others have a straight free
margin. ‘The marginal plates appear as if bent upon themselves to form their outer
margin, at a rather acute angle, receiving the extremities of the rib im a depression
excavated in the concavity of the angle; they are nearly twice as long in the direction
parallel with the margin of the carapace than transverse to it, and they are traversed
in the latter direction, along the middle of their upper surface, with the groove or
impression of the marginal scutes. The free edge of the upper plate of the marginal
pieces is slightly notched above the insertion of the rib, and they correspond with those
of the Chelonite, from the Burham chalk pit, in the collection of Sir Philip de M. Grey
Egerton, Bart., F.R.S.

The form of the median or vertebral scutes of the perishable “ tortoise-shell,”
may be traced by their somewhat wide and moderately-deep impressions. They
progressively diminish in size from the second to the fifth, which is the smallest, and
which covered the ninth and the major part of the eighth and tenth neural plates ;
but their relative breadth and the outward extension of their lateral angles correspond,
like the characters of the more enduring parts, with the type of structure of the
marine turtles. The breadth of the first vertebral scute is 1 inch 8 lines, that of the
second scute is 2 inches, that of the fifth scute is 1 inch.

The coracoid is a bone that varies in form so as to be very characteristic of the
different genera of Chelonians; it is a triangular plate in Zestudo, a more elongated
triangle in Chelys, a broad, bent, elongated plate in Zrionyr, a narrower bent plate in
Fnys, a long, straight, slender bone, slightly expanded and flattened at the sternal
end, in Chelone: now it is precisely the latter form that this bone (T. II, fig. 2, 52, 53),
fortunately preserved in the present specimen, here exhibits, showing that the same
modifications of the skeleton, in reference to the actions of swimming, are combined
in the past as in the present species of Chelone; it is 1 inch 7 lines in length,

CRETACEOUS FORMATIONS. 7

cylindrical at its humeral half, and gently expanded to a breadth of 3 lines at its sternal
end. The proportion which this bone presents of one fourth the length of the
carapace is only paralleled in the existing Chelones; it is much shorter in the Himydes.

The hyosternal and hyposternal bones resemble rather those of the Turtles than of
the young Emydes; certainly no Himys, with a carapace 5 inches in length, presents
such forms as these bones exhibit in the present fossil; several rays or pointed spines
of bone are developed from the anterior half of the median margin of the hyosternal
piece, as in Chelone caretta ; the rest of the margin continues to form the circumference
of the large central aperture of the sternum. The hyposternal sends similar rays from
the posterior half of its outer margin, leaving the anterior half to join, probably the
same proportion of the outer margin of the hyosternal, so as to form a deep, lateral,
angular notch of the sternum. The length of the hyposternal is 1 inch 2 lines. The
epi-, ento-, and xiphi-sternal bones are not preserved.

From the preceding description, it must be obvious, as has been already observed,
that the present Chelonite of the chalk can only be supposed to belong to the genus
Emys, on the supposition that it is a very young specimen of some unusually large
species ; but against this supposition, the poimted form of the hind end of the carapace,
the regularity of the size of the marginal plates, the non-development of the lower
margin of any of these plates for a junction with the plastron, the long and slender
coracoid, the narrow elongate form of the vertebral plates, and the broad vertebral
scutes, collectively and separately militate. Whilst in all these modifications, the Turtle
from the Chalk so closely corresponds with the true Chelones, that I cannot hesitate to
refer it to the marine family of the order.

From the breadth-of the xiphisternals in the remains of this species first described
by me, I was induced to suppose that a new subgenus (Cimochelys) of marine Turtles
was thereby indicated, having a closer affinity to the Hmydes than the typical species ;
and the same affinity seems to be shown by the more regular elliptical form of the
carapace of Mr. Bensted’s beautiful specimen. The structure of the cranium, when
this desirable part of the skeleton is discovered, may confirm the propriety of the sub-
generic distinction ; but the numerous decided marks in other parts of closer affinity
to Chelone leave no alternative than to regard the fossil species of the chalk as a
member of that genus.

It differs from all known species, especially the sub-carinated species of Sheppey
(Chelone subcarinata and Chelone subcristata), m the form of the carapace, which is more
truly elliptical than in any other species with which I am acquainted.

A second specimen of Chelone Benstedi, of the same size with that above described,
also obtained from the lower chalk at Burham, in Kent, and now in the fine collection
of J. S. Bowerbank, Esq., F.R.S., gives a better view of the upper surface of the
carapace, but the marginal plates have been dislocated and pressed inwards beneath
the narrow pointed ends of the ribs. All the neural plates are narrow and carinate

8 FOSSIL REPTILIA OF THE

above. They area little broader in front than behind. The slight angular production
of the middle of the outer border of the posterior marginal plates is somewhat better
marked than in the preceding specimen, and it gives a serrated character to that part
of the circumference of the carapace which is formed by those marginal plates.

An upper view of Mr. Bowerbank’s specimen is given in T. III, fig. 1; a side
view in fig. 2; an oblique front view, showing some of the anterior marginal plates
in fig. 3; and an outline of the transverse vertical section of the Turtle in fig. 4:
all of the natural size.

CHELONE PULCHRICEPS, Owen. T. VII 4, figs. 1, 2, 3.
Report on British Fossil Reptiles, Trans. British Association, 1841, p. 172.

With the exception of a few more or less mutilated mandibles, no parts of the
skull of a Chelonian reptile have been, hitherto, discovered in the chalk itself, either
at Burham or elsewhere in England; but I have had the opportunity, through the
kindness of the Rev. Thomas Image, M.A., of Whepstead, of examining and com-
paring the fossil cranium of a small turtle from the green-sand which underlies the
chalk. The specimen was discovered near Barnwell, in Cambridgeshire. The general
form of the skull is elongate and depressed ; and it is chiefly remarkable for having
the nasal bones (15) marked off by a suture from the pre-frontals (14), being a return
to the typical characters of the vertebrated cranium, which I have also noticed in
the skull of a larger turtle, from the Portland Stone, where, however, the course of
the suture is different.

The characters of the genus Chelone are clearly expressed in the skull of the
Chelone pulchriceps, by the extensive roof of bone over-arching the temporal fosse,
and by as large a proportion of this roof being formed by the post-frontals (12) as in
existing Chelones. ‘The orbits are also large, and their superior interspace is broad.

The median or true frontals (11) form a small proportion of the upper border of the
orbits; the anterior extremities of the median frontals, instead of converging to a
point, are extended forwards, between the pre-frontals, in a broader proportion than
in the Portland turtle, and are obliquely truncated: it is only in the genus Chelys
among existing Chelonians, that the pre-frontals are thus separated from each other ;
but in the Chelys, the intervening extremities of the frontals are continued to the
upper border of the external nostril. In the present fossil cranium, the median
extremities of the pre-frontals are arrested at the distance of four lines from the
nasal aperture, which is bounded above by two distinct nasal bones (15) ; these bones are
joined by suture to the frontals, to the pre-frontals, and to the superior maxillaries (21) ;
the nasal processes of which extend upward, and exclude the pre-frontals from the
nasal boundary. The superior maxillaries are traversed obliquely by a large and

CRETACEOUS FORMATIONS. 9

deep scutal impression, above which the superior maxillary forms a convex promi-
nence at the anterior part of the orbit. The groove, which traverses the frontals,
is as strongly marked; that which impresses the post-frontals is fainter. The
expanded trumpet-shaped portion of the tympanic bone comes nearer the upper
margin of the cavity than in existing Chelones.

The palatal bones (20), have no palatal process anterior to the inner nostril, as
in the Chelone cuneiceps* and modern Turtles; but are situated behind that aperture,
as in Hmys and Trionyz, and the vomer does not penetrate between them. The
palatal processes of the intermaxillary and maxillary bones form an unusually pro-
minent angular ridge, running nearly parallel with the trenchant margin of the jaw;
the bony palate is not extended along the middle line beyond the intermaxillaries,
which here enter into the formation of both the inner and outer nostrils. The
pterygoid bones present moderately wide and deep external emarginations.

The following are the chief dimensions of this fossil skull :

In. Lin.
Length of the cranium from the occipital tubercle 2 4
Breadth of the cranium above the tympanic cavities ©
Depth of the cranium at the parietal bones ©
Antero-posterior diameter of the orbit oO 9
Breadth of the interorbital space ° 5 5 O &

The supracranial scutation of the Chelone pulchriceps much resembles that of the
Chelone Couanna. A large oval syncipital scute defending the middle region of the
epicranium, and being surrounded by the smaller “ frontal,” ‘“ superorbital,” “ pa-
rietal,” and “ occipital” scutes: the bones supporting the latter have, however, been
too much mutilated to allow of their proportions and forms being determined. The
fronto-nasal scutes are each bounded behind by well-defined bold curved lines, convex
towards the frontal scute, and deeply indenting the frontal bones. Amongst the
existing Chelonia, the character of the distinct nasal bones has been, hitherto, met
with only in an Emydian species, on which the sub-genus Mydromedusa has been
founded. ‘The modifications of the bony palate in the Chelone pulchriceps afford
another indication of its Emydian affinities.

CHELONE CAMPERI, Owen. (?) Tab. V.

Larce Turtie, Camper. Philosophical Transactions, vol. lxxvi, 1786.

I am induced provisionally to refer to the above species the two large bony plates
or scutes figured in T. V, on account of their size, their shape, and especially their
carinate structure. They have a smooth exterior surface, marked only by faint lines
radiating from the median “ carina’ or ridge. They are thickest at this part, which

* Monograph on the Chelonia of the London Clay, t. xv, fig. 3, 20.

10 FOSSIL REPTILIA OF THE

is from one to two lines, and become gradually thinner to their peripheral border,
which, however, is too much fractured to show whether it has been terminated by a
dentated suture like the neural plates, which unite with the costal plates in the
ordinary Chelones. The degree of thinness of the actual margins of the large
scutes in question shows that they were not suturally united to costal plates. On
the hypothesis, therefore, that they are the median or neural plates of a Turtle, they
can only be referred, as not uniting laterally with costal plates, to the ninth and tenth
of the series of neural plates, which are under the same circumstances, and which also
differ from the eight preceding plates, in having contracted no osseous continuity or
adhesion to the subjacent neural spines. In order to test this particular conformation
I carefully excavated the chalk matrix beneath the median part of both scutes to
beyond the middle of it, and exposed only a smooth concave surface: there was no
trace of the median ridge, which is continuous with the summit of the spine, in the
first eight neural plates of the Chelonia.

But besides the two plates, the exterior surface of which is exposed, there is a
third plate, the position of which is reversed, and which has slipped under one of the
scutes that has retained its natural position. A portion of a fourth similar plate is
also present in a similar reversed position in the same block of Chalk. This fact,
together with the thin borders of the plates, leads me to suspect that they may belong
to the series of marginal plates of a large Turtle, notwithstanding the open angle at
which the sides diverge from the median ridge, which, in that case, must have formed
the outer and anterior border of the carapace.

On the hypothesis that these large plates have belonged to a Turtle, they indicate
an individual with a carapace between forty and fifty inches long; as large, for
example, as that of which CaMpER makes mention in the memoir above quoted.
There is a possibility, however, that those large scutes may have belonged to some
Saurian reptile, although the probability is small, on account of the absence of any
rugosities, pits, or other sculptured character which marks the exteroir surface
of all the dermal bony scutes of Saurians hitherto found. It is possible that the
Polyptychodon, or the Mosasaurus, if their skin was so defended, might have had
light and smooth scutes; but the balance of evidence is at present in favour of the
Chelonian character of those in question. Their microscopic structure shows that
they have not belonged to a cartilaginous fish, and it agrees pretty closely with that
of the osseous tissue of unquestionably Chelonian neural plates of smaller size, from
the chalk formation.

Another circumstance which also inclines me to view the large plates above
described as being Chelonian, is the corresponding thinness of the costal plates where
they are unattached to the subjacent ribs in the specimen from the Burham Chalk-
pit, figured in T. VI, fig. 3. The outer surface of these plates is also smooth, or at
most marked by fine striz. The borders by which they are in contact do not show

CRETACEOUS FORMATIONS. a

any very distinct character of suture, but appear to have been jomed by a wavy
line. The length of the rib which projects beyond the conjoined costal plate is con-
siderable, being proportionally greater than in the much smaller Chelone Benstedi ; and
the free portion of the rib is narrower, with a smoother upper surface, evidently indi-
cating a distinction of species. ‘The portion of carapace in question may belong to a
young Chelone Campert.

Of the marginal plates of that species only the anterior ones appear, as yet, to
have been discovered at Maéstricht; but the liability of such slightly attached parts
to be scattered and lost, renders their discovery in natural connection, as in the speci-
mens in T. V, more remarkable, perhaps, than their absence, and affords, at least, no
sufficient grounds for the speculation of Faujas St. Fond, that they were cartilaginous
in the large Turtle from Maéstricht. The outer surface of the bones of the carapace
of the Chelonian Reptiles which actually retain the marginal plates in a gristly state,
is characterised by a sculptured character, well shown in several plates of a former
Monograph, ex. T. XVI, but of which no trace exists in the Chelone Camperi, from
Maéstricht, any more than in the neural or marginal plates in Tab. V, or the costal
plates in Tab. VI of the Chelonites from the upper chalk of Kent.

CHELONES INDETERMINATS.

Various portions of the fossilised skeletons of Chelonian Reptiles have been kindly
submitted to me by Mrs. Smitu, of Tonbridge Wells; by J.S. Bowerbank, Esq. ;
and by THomas CHARLES, Esq., of Maidstone, from which specimens I have selected
the subjects figured in T. IV, T. VI, and T. VII 4.

The specimen, fig. 8, T. VII 4, from the Collection of J. S. Bowerbank, Esq., is of
a similar nature to those above described and figured in T. V; but it is rather
smaller, and is more decidedly shown to belong to the marginal series of scutes by the
unsymmetrical development of the two sides which slope away from the median
ridge; and this, also, is oblique: the sides form a less open angle: their substance,
which is hardly a line in thickness at the meridian ridge, gradually thins off to the
border, which is produced on one side into a number of dentated processes, that to
all appearances are natural.

There are two similar but rather smaller marginal scutes in the same Collection.

Mr. John Quekett, the Assistant Conservator of the Museum of the Royal College
of Surgeons, has kindly prepared sections for the microscope from the preceding
specimens, and the form, size, and arrangement of the bone-cells agrees with those in
similar preparations from the scutes of the recent Turtle.

The portion of mandible, T. VII 4, figs. 4 and 5, resembles that of the Chelone
planimentum, TV. 1X, of a former Monograph, and of some of the Eocene Turtles from
Bracklesham, figured in Mr. Dixon’s work ‘On the Tertiary and Cretaceous Deposits
of Sussex, Tab. XIII, in the great extent of the bony symphysis; but this differs in

12 FOSSIL REPTILIA OF THE

having the upper surface traversed by two longitudinal furrows, slightly converging
as they approach to the point. The outer or alveolar borders are obtusely rounded ;
and are perforated, as m most Chelonians, by a series of small vascular foramina : the
rounded border increases in breadth as it extends backwards where it is continued
upon, or forms, the outer surface of the beginning of the ramus of the jaw. The com-
mencement of the coracoid process rises from the inner border of the ramus which is
continued from the hinder and upper border of the broad symphysis. In this
character, also, the present mandible differs from all that I have previously seen,
either fossil or recent. In its general form it resembles, like some of those from the
Bracklesham Clay, the mandible in the Zrionycide, rather than that in the existing
Chelones. The specimen is in the Collection of James 8. Bowerbank, Esq., F.R.S.

In the same rich depositary of British Fossil remains is the portion of a Chelonian
mandible, T. VIL4, figs.6 and 7. It has formed part of a longer, narrower, and more
pointed lower jaw than the one above described. The bony symphysis is much
shorter; the rami longer, deeper, and more regularly convex on their outer side. It
thus, likewise, presents the characters rather of a Zrionyxr than of a modern Chelone ;
but the modifications of the lower jaw, in indubitable species of true Turtle from
the older Tertiary deposits, forbid a conclusion against its having belonged to a
similarly modified species of Chelone.

I am indebted to Mr. Catt, of Brighton, for the specimens of the right scapula and
coracoid, in almost their natural juxta-position, of a Turtle which must have been
about two feet in length, from the chalk, T. VII4, fig. 9. The letter @ shows the
surface contributed by the scapula to the humeral joint, the letter 4 that by which it
was united with the coracoid: ¢ is the base of the acromial process or clavicle, which
has been sent off in the same oblique direction as im the recent Turtles; d is the
beginning of the body of the slender scapula. The coracoid has been rotated, so as
to show its scapular surface at 4: that which it contributed to the shoulder joint is
shown at a: the long and slender shaft of the coracoid and its very gradual expansion
is eminently characteristic of the marine nature of the species to which it belonged.

In Tab. VIL4, fig. 10, is shown the opposite side of the right coracoid of a Turtle
of double the dimensions of that from which the preceding specimens came. It is
from the chalk-pit at Burham, so fertile in fine fossils, and forms part of the collection
of Mrs. Smith, of Tonbridge Wells. The margin of the articular end is more produced
than in the Chelone mydas, and, as in the preceding fossil, the articular surface 4 for the
scapula is relatively less im proportion to that for the humerus @, than in the same recent
Turtle: the slender beginning of the shaft of the bone is more compressed, less triedral.
I estimate the fossil fragment, by the proportions of that of the Chelone mydas, to have
been part of a coracoid of one foot in length, and calculating the proportions of the
carapace by those of the Chelone Benstedi, it must have been about three feet six inches
in length in the Turtle from which the coracoid in question came.

CRETACEOUS FORMATIONS. 13

T. IV, fig. 1 is the slender portion of the entosternal, es, and a fragment of the
right hyosternal of a turtle, which must have been about one foot eight inches in length.

Figure 2 gives an inside view of a rib, with the connate costal plate, the gradual
narrowing of which towards the free end of the rib resembles that in the Chelone
Benstedi.

Figure 3 is a similar specimen from the carapace of a larger turtle, with the neck
of the rib more freely relieved from the connate costal plate.

Figure 4 is a more mutilated example of a larger rib and costal plate.

Figure 5 is the right hyposternal of the Chelone Benstedi, and has belonged to a
specimen not larger than either of those figured in T. I—III.

Figure 6 is the humeral end of the connate scapula and clavicle of a turtle.

Figure 7 is the outer side of a marginal scute of a large turtle.

Figure 8 is the left humerus of a turtle, which differs from that of the existing
species in the greater expansion of its distal end.

Figure 9 is the left ulna of a turtle, belonging to a larger example than that to
which the humerus belonged.

I have been favoured with the opportunity of inspecting portions of the skeleton
of a large Chelonian obtained by Mrs. Smith, of Tonbridge Wells, from the lower
chalk at Burham, Kent, and skilfully relieved from their mineral bed by that lady.
The principal bones consist of two series, one containing five, the other three and
parts of two, of the marginal plates of the carapace, in natural connection, and from
that part of the margin where they receive the extremities of the vertebral ribs (T. VI,
figs. 1 and 2). These marginal plates in Chelone mydas are three-sided, and have two
thick terminal borders by which they are united, suturally, to one another: of the three
free surfaces, the one, directed towards the interior of the body, is concave and
characterised by a deep depression for the reception of the tgoth-like extremity of
the rib (fig. 2); the other two (upper and under) surfaces meet at an angle, which is
produced at certain parts to form the marginal dentations of the lateral and posterior
parts of the carapace in that species of turtle, but is more open and obtuse in the
marginal plates at the anterior part of the carapace. In the fossil the marginal plates
have the general characters of those of the genus Chelone, but differ from those of
the Chelone mydas in bemg more concave on the central or perforated side, and they
are also concave at the upper side, and in a slighter degree at the under side; these
sides likewise meet at a more acute angle, and this angle is produced into a sharper
and more continuous ridge; but this ridge subsides at one end of the series of plates
in fig. 1, and the upper and under sides gradually meet at a more open angle, which
is rounded off in the first of the series. This plate, therefore, answers to the third
marginal plate in the Chelone mydas, or that which receives the end of the first
expanded vertebral rib; and the remainder, therefore, to the fourth, fifth, sixth, and
seventh marginal plates: now these are precisely the marginal plates in the Himys

14 FOSSIL REPTILIA OF THE

which have their inferior margins developed inwards, and articulated by suture to the
lateral wall of the carapace: but these margins not being so developed or terminated
in the present fossil, but, on the contrary, being inferior to the upper margin in
breadth,* and terminating like that margin in a blunted edge, prove the present
Chelonite to belong, like the smaller Chelonite from the same chalk-pit already
described, to the marine genus Chelone.

The length of the carapace of the Chelone mydas is about nine times that of the
sixth marginal plate, whence I calculate the length of the carapace to which the
marginal plates here described belonged to have been about fourteen inches.

The following admeasurements will show the different proportions of the marginal
plates of the present specimen as compared with the corresponding ones of a Chelone
mydas of similar general size :—

Fossil Chel. Chel. mydas.
In. Lin. In. Lin.

Length of the series of five plates in a straight line . 7B 3 2
Breadth of the upper surface of the third (fifth) e eatal 0 10
Interspace of costal depressions. c : c Wi = 6

Thus the marginal plates of the chalk turtle, besides bemg more concave, are
broader in proportion to their length, or antero-posterior diameter. In these respects
they correspond with the form of the marginal plates in the Chelone Benstedi, but
more evidence must be had, before these large fossil marginal plates can be referred
to a larger and older specimen of the species.

There are other two marginal plates imbedded in the same portion of chalk, with
their upper, smooth, slightly concave surfaces exposed; and the toothed or sternal
extremities of three of the vertebral ribs, which by their length and size also prove
this specimen to be a Turtle. One of these fragments of rib measures 53 ches, and
the expanded plates developed from each side of its upper surface are concave on
their exterior surface, which is flat or slightly convex in Chelone mydas.

A separate portion of chalk from the same pit contains the scapula and its acromial
branch or anchylosed clavicle, with the articular surface which joins with the coracoid
and humerus. The angle at which the scapula and clavicle meet is more open in Chelone
than in Lmys or Chelys: the present specimen presents the same angle as in the
Maéstricht Chelone figured by Cuvier,* in which it is rather more open than in the
recent species of turtle. A broad, thin, slightly concave plate of bone appears, by

the radiation of the fine strize at its under part, to represent the expanded parietal
bone of the cranium.

* The upper margin, which is distinguished by a slight notch where the costal groove leads to the pit,

is broader than the lower one, in these plates of the Chelone mydas; but the difference is less than in the
present fossil species.

+ Ossem. Foss., tom. v, part ii, pl. xiv, fig. 5.

CRETACEOUS FORMATIONS. 15

Genus, PROTEMYS, Owen.

In the operations of quarrying a rock of the hard variety of the gray arenaceous
limestone, called “Kentish Rag,” which belongs to the ‘‘Green-sand” Formation,
near the town of Maidstone, in Kent, Mr. Bensted, the owner of the quarry, had
the good fortune to discover the dislocated remains of the carapace and plastron of
a Chelonian reptile, which remains were grouped together in a slightly dislocated
mass, having a circumference of three feet. This fine specimen, still unique of its
kind, has been liberally transmitted, by Capt. Guise, F.G.S., its present possessor, to
me for the purposes of being described and figured in the present Monograph.

It represents, as will be shown in the account that follows, a distinct sub-genus in
the Family Himydide, which may be characterised as follows :—

Sternum dilatatum, per gomphosin cum testa conjunctum, suturis hyo-et hypo-sternorum

in medio lateribusque sterni interruptis.

PROTEMYS SERRATA, Owen. Tab. VII.

The specimen consists of the principal part of the carapace and a small part of
the plastron. The carapace presents an ovate form, being apparently widest about
two thirds from the nuchal plate. Both the nuchal (T. VII, cz) and the pygal
(ib., py) plates are preserved, and the total length of the carapace is 1 foot 13 inch.
The extreme breadth of the carapace at the part above indicated appears to have
been about 9 imches. The carapace is moderately convex, but becomes concave
near the margin of the hinder half, by a slight upward curve of the marginal plates
there.

The nuchal plate is tranversely oblong, slightly but widely emarginate anteriorly,
3 inches 9 lines in transverse length, 1 inch 2 lines in the axis of the carapace.
The first vertebral scute, » 1, advances within three lines of the anterior border of the
nuchal plate, which bears the impressions of a small nuchal scute 10 limes wide, of
the first marginal scute, and of part of the second marginal scute on each side.

The first costal plate, (pi. 1,) articulates anteriorly with the nuchal and first
marginal plates, m 1, and is connate with the subjacent rib to within half an inch of
its pomted end, which penetrates or abuts against the third marginal plate, m3. It is
impressed by the triradiate line of union of the first, »1, and second, »v 2, vertebral
scutes with the first costal scute. The rib forms a strong projection on its under
surface, as is shown by the impression on the left side of the carapace. The length
of the first costal plate, exclusive of the free end of the rib, is 2 inches 8 lines. The
first neural plate is lost. The second, s 2, is long and narrow, and has been, apparently,

16 FOSSIL REPTILIA OF THE

notched posteriorly, between the two truncate angles. Its length is 1 inch 5 lines;
its breadth 6 lines: there is no appearance of a carina on its upper surface. The |
second costal plate, pi.2, is 3 inches 2 lines in length, 1 inch 4 lines im breadth;
it is slightly concave in the axis of the carapace; convex in the direction of
its own length or across the carapace. On the right side it is fractured, and its outer
end is overlapped by the dislocated fourth marginal plate, m4, ito the upper border
of which the free end of the rib, which now projects below it, was implanted. The
upper surface of the costal plate is impressed by the triradiate line of union of the
second vertebral scute, » 2, with the first, ¢1, and second, ¢2, costal scutes. The
third, pi.3, and fourth, pi.4, costal plates have their median ends straight with the
posterior angles truncate. About seven lines of the free end of the connate rib pro-
jects beyond their broad outer ends. Beyond these the carapace is broken through
by the pressure of the plastron from below: the upper surfaces of the conjoined
hyposternals appear at ps, ps, the dislocated parts of the carapace, which were above
them, having been removed. The outer portions of the fifth and sixth costal plates
are seen on the right side, terminating the one, pi.5, between the seventh and ‘eighth
marginal plates, the other, pi.6, between the eighth and ninth marginal plates. The
seventh and eighth, pl. 7, p/.8, costal plates are preserved on the left side. The median
ends of the eighth pair seem almost or quite to have met anterior to the ninth neural
plate, s 9, as in the Hmys /evis,* the ninth plate presents a triangular form with the
apex turned forwards: the breadth of its base is 1 inch 7 lines, its length is
1 inch. The tenth neural plate is a hexagonal one, 1 inch 10 lines im length.
It articulates immediately with the pygal plate, py, which is subquadrate, rather
broader behind, where it is notched in the middle. Its length is 1 inch 5 lines; its
breadth 1 inch 8 lines. Not any of these neural plates are carinate.

The left hyosternal (ps) has been displaced, so that its under or outer surface
would be in view in the block displaying the upper surface of the carapace, T. VII,
were not the major part of its substance retained in the other half of the block, which
therefore shows in part the contour of its upper or inner surface, T. VII 4, ps, from
which, however, the produced outer and anterior angle is broken off, that part
remaining attached to the other moiety at ps, T. VII, where it dips beneath the
border of the carapace. It is this produced angle which, bending upwards and for-
wards, effects the union between the plastron and carapace at the fore part of the
lateral wall, by its insertion into the carapace; and it affords the chief proof of the
Emydian affinities of the Chelonite under consideration.

Yet in some respects, the hyosternal in the fossil resembles more that of a young than
of an old Emydian: its median border is not straight, and the concavity of the hinder
half of that border indicates a persistent vacuity in the middle of the bony plastron ;

* Monograph on the Reptiles of the London Clay, t. xxii, fig. 1.

CRETACEOUS FORMATIONS. 17

the posterior border is convex, showing that it was not united in its whole extent to
the corresponding anterior border of the hyposternal.

With the broad nuchal plate (ca) is articulated the first marginal plate m1, of the
right side: its upper surface is square, and is impressed by the junction of the first
costal scute with the second and third marginal scutes. The second marginal plate
is lost. The third is displaced, and its concave side is turned upwards: the upper
and under walls of the concavity are of almost equal extent, and meet externally at
aright angle. Unless the back part of this plate has been turned forwards, it differs
from the corresponding plate in the Emydians in not having the inner concavity con-
fined to the posterior part, but extending its whole length, as in Thalassians ; its
proportions, however, are such as we find in the genus Hmys. The fourth margmal
plate, m4, has its inferior and superior walls equally produced, as in Emydians, and
meeting at a right angle: it articulates with the second costal plate, and probably,
also, with the hyosternal below, but it has been displaced upwards. ‘The fifth
marginal plate is lost. Only the outer margin of the sixth, m6, is produced; this
also shows an upper and an under plate meeting at a right angle. The seventh
marginal plate, m7, which is preserved on the left side, although fractured, shows its
rapid progressive compression towards its posterior border. The eighth marginal
plate, m8, is a broad, subquadrate, depressed plate, with a thin outer margin, and
the thicker inner margin slightly produced into the angle between the fifth and sixth
costal plates: its upper surface is concave, and impressed with the T-shaped union
of the third costal scute with the eighth and ninth marginal scutes. The ninth
marginal plate, m9. presents a similar form; its outer border is injured. In the
tenth marginal plate, m 10, the impression of that border is left on the matrix, showing
that it had an angular notch. The same character is as strongly marked in the
eleventh marginal plate, m11, and the pygal plate, as has been already observed is
notched at the middle of the posterior border. It is from the consequent serrated
character of the hinder border of the carapace that the specific name has been taken.

Compared with the existing species of the genus Chelone, the present fossil differs
greatly in the completeness of the ossification of the carapace, due to the extension of
the costal to the marginal plates: in the form and proportions of the marginal plates,
especially from the first to the seventh inclusive; and in the form of the recognisable
elements of the plastron, more particularly in the curved and produced angle of the
hyosternal. But when we compare it with some of the extinct Turtles of the Eocene
epoch, as e.g., Chelone longiceps, Chelone convexa, and Chelone subcarinata, the differ-
ence in regard to the extent of ossification of the costal plates is less; whilst the
persistent partial want of union between the elements of the plastron in the present
fossil, approximates that part of its skeleton to the condition of the plastron in the
Eocene Chelones above cited, in which the ossification of the plastral elements has
proceeded further than in the typical Turtles.

oo

18 FOSSIL REPTILIA OF THE

In these extinct species, the life-periods of which successively stretch backwards —
in time from the oldest Tertiary to the newer Secondary Epochs, there is plain
evidence of a gradual breaking down of the distinctions that now trenchantly divide
the fresh-water from the marine species: the actual interval being then filled up by
several well-marked species, that have apparently perished.

The Thalassian affinities of the Emydoid Chelones of the Eocene Period were,
nevertheless, in some instances well established by the structure of the shell, and by the
forms and proportions of the limbs,—parts, which it is important to bear in mind, are
more constant in their nature than the dermal ossifications on which the solidity or
otherwise of the carapace and plastron depends. And it must also be remembered,
that with the transitional species, there were associated good typical forms of Turtle,
e. g., Chelone planimentum and Chelone crassicostata, as well as of Fresh-water
Tortoises ; e.g., Hmys levis, Hmys bicarinata, Platemys Bullockit.

The Chelonite from the Maidstone Green-sand, which forms the subject of the
present section, deviates from the typical Emydian structure in the arrest of the
dermal ossification requisite for the complete solidification of the plastron, and,
perhaps, also in the form of the third pair of marginal plates ; but, with the exception of
this doubtful point, the structure and form of every other element of the carapace are
more strictly Emydian, than in the most modified of the Eocene Chelones above cited ;
and the Emydian affinity is more decisively shown in the form of the hyosternal ele-
ment, T. VII and VIIA, fig. 1, Ay. The departure of which from that of a mature typical
Emys does not bring it so near to the form of the same element in the typical Chelone,
as it does to that of an immature Hmys, T. VILA, fig. 1*. In the nature and amount
of departure from the Emydian type recognisable in the Profemys serrata, there is
plainly to be seen an arrest of the development of the plastron, which so far as it
has proceeded, has followed that type: there is no trace of a deviation from the
embryonal common fundamental pattern of the part towards the special modifications
characteristic of the genus Chelone.

In the small Turtle from the Chalk (Chelone Benstedi) the ossification has extended
from the hyosternal and hyposternal centres by many diverging rays; the inferior
plates of the marginal bones, T. II, fig. 1, 1-12, are feebly and subequally developed
throughout; and there are other differences from the Protemys serrata of the Green-
sand, which no degree of immaturity in the Chalk specimens exhibiting them would
explain, as, e.g., the carmated neural plates, T. I and III, s,s, and the pointed
pygal plate, T. I, fig. 1, py.

Were a recent form of Hmydian, so modified as the large species from the
Maidstone Green-sand, to be presented to the study of the modern Erpetologist, one
cannot doubt, but that it would be referred to a distinct sub-genus in the Fresh-water
family; and I have accordingly characterised such, as far as the condition of the
Chelonite in question will permit. It is to be hoped, that future discoveries may bring

CRETACEOUS FORMATIONS. 19

to light the modifications of the head and limbs of the Protemys: from those of the
plastron we may infer that the species was more aquatic in its habits than the
typical Emydians. The Protemys serrata may have been an Estuary species, and its
discovery in the same formation and quarry as that in which the remains of an
Iguanodon have been found, adds probability to the explanation of the occurrence of
the latter in a Green-sand or Neocomian Deposit, on the supposition that the carcase

had been drifted out to sea.

OrvER—LACHRTILIA.

In passing from the Tertiary to the Secondary periods of Geology, in quest of the
evidences of Reptilian organisation, we have found no material change in that of the
Chelonian order; the characters by which the marme species are now generically
separated from other 7?studines of Linneeus, and which were not deemed worthy
of that distinction by the great systematic reformer of Natural History, are recog-
nisably retained in the old Turtles, the contemporaries of the Ichthyosaurs, Plesiosaurs,
Pterodactyles, and Belemnites, that swam the ocean in which the Corals and Sponges
lived, which deposited the main part of the material that now constitutes our Chalk
Downs. The differences which are traceable on a comparison of the Turtles of that
period with those of the Tertiary deposits and of the actual seas, merely prove them
to have been distinct species, with some slight indications of a nearer affinity to the
Emydian type of structure than we observe in the present representatives of the genus
Chelone. A

The Lizards of the present day are characterised, with the exception of one genus,
Gecko, by the same cup-and-ball articulation of the vertebrae as the modern Crocodiles,
viz. with the cup at the fore part of the body of the vertebra and the ball at the back
part, an arrangement signified by the term ‘‘ proccelian,” as applied to such vertebre.
The fossil Lizards of the Cretaceous period, whether terrestrial, amphibious, or more
especially modified for marine life, present the same proccelian type.

Tribe, REPENTIA.

Genus, RAPHIOSAURUS, Owen.
‘Transactions of the Geological Society,’ vol. vi, 2d Series, p. 413, April, 1840.

Species, Raphiosaurus subulidens, Owen, (Tab. X, figs. 5 and 6).
Report on British Fossil Reptiles, ‘Trans. of British Association,’ 1841, pp. 145, 190.

In a Memoir communicated to the Geological Society of London in 1840, and in

20 FOSSIL REPTILIA OF THE

my ‘Report on British Fossil Reptiles,’ published in the volume of ‘ Reports of the
British Association’ for 1841, p. 145, I proposed the name of Raphiosaurus™ for a genus
of small extinct lacertine Svuria, characterised by slender awl-shaped teeth, attached
by anchylosis in a single series to the bottom of a shallow alveolar groove, and to the
inner side of an outer wall or parapet of the same groove; thus corresponding with
that type of saurian dentition called ‘ pleurodont’ amongst modern Lizards.

The specimen figured in T. X, figs. 5 and 6, was discovered in the Lower Chalk
near Cambridge, and forms part of the rich collection illustrative of the Cretaceous
Formations of Cambridgeshire, in the possession of JAMES CaRTER, Esq., M.R.C.S.,
to whose kindness I am indebted for the opportunity of describing the specimen. It
consists of a considerable portion of the dentary part of the lower jaw, and contains
twenty-two of the above-described teeth, arranged in a close series: in fig. 5 some
teeth are shown in place; in fig. 6, a, 6, and c show teeth with the crown broken off ;
and below fig. 6 is the groove or incomplete socket of a shed tooth.

At the period when this fossil was described,t the only vertebre of a lacertine
Saurian, which at all approximated to the proportions of the species indicated by the
jaw and teeth of the Raphiosaurus, were those which Sir Philip de M. Grey Egerton,
Bart., had kindly submitted to my inspection, and which are figured in the volume of
the ‘Geological Society's Transactions’ already cited.§ That chain of vertebree was
discovered in the lower chalk of Kent, at Burham pit, and manifested specific distine-
tions from the vertebree of the existing genera of Lacertians, with which I was able to
compare them in 1840; and at that time I could only suggest, when pressed fora closer
determination, that, on the hypothesis of their having belonged to the same species
as the fossil Lacertian from the Cambridge Chalk, they must be referred to a Lizard
generically distinct from any known existing species. Other specimens with which my
lamented friend Mr. Dixon subsequently supplied me, have rendered it highly probable
that the vertebree (figured in T. X, fig. 4) belonged to an extinct Lizard, distinct from
the Cambridge Raphiosaurus, with the vertebral characters of which species we are
still, therefore, unacquainted.

I have been favoured, by W. H. Bristow, Esq., with the inspection of portions, about
one inch and a half in length, of the upper and lower jaws of a Lizard; the rami of
the lower jaw being a third of an inch in depth, with long, slender, awl-shaped teeth,
answering to those of the Raphiosaurus. There were five of these teeth fully formed
in the portion of the upper jaw, with intervening small ones in the course of develop-
ment. The portion of lower jaw had three or four irregular rows of small apertures
opening on its outer side. These specimens were found in the chalk at Northfleet.

* From pagior, an awl; cavpos, a lizard. + Odontography, 4to, p. 182.
{ Transactions of the Geological Society, 2d Series, vol. vi, p. 412.
§ Ib. p. 413, pl. 39, fig. 3.

CRETACEOUS FORMATIONS. 21

Genus, CONIOSAURUS,* Owen.

Species, Contosaurus crassidens. (Tab. IX, figs. 13, 14, and 15.)

Dixon’s ‘Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex,’ 4to, p. 386.

Two genera of Lizards of the Cretaceous period, with proccelian cup-and-ball
vertebrze, similar in size and form to those of the series figured and described in the
‘Geological Transactions,’ vol. vi, 2d ser., pl. 39, fig. 3, are now no longer hypothetical,
but have been satisfactorily established by the discovery of portions of jaws and teeth
associated with such vertebree. The first of these specimens, which discloses a small
extinct Lacertian,. distinct from Raphiosaurus, and characteristic of the chalk formation,
was obtained from the Middle Chalk at Clayton, Sussex, and forms part of the choice and
instructive collection of HENRY Cart, Esq., of Brighton. It is figured in T. IX, figs. 14
and 15, anda group of vertebre of apparently the same species is represented in fig. 13.

These vertebra are represented of the natural size. Like those first figured in the
‘Geological Transactions, tom. cit., pl. 39, they present an anterior concavity or cup,
and a posterior ball upon the bodies for their reciprocal articulation ; and a tubercle is
developed from each side of the vertebral body near its anterior end, for the articulation
of the rib. The non-articular surface of the vertebra is smooth; its under part is
concave in the axis of the body, convex transversely. On the very probable supposition,
however, that the vertebree in fig. 14 belonged to the same animal as the jaw which
is imbedded in the same portion of chalk, such vertebree must be smaller in proportion
to the head than in the extinct species of Lacertine Saurian,'T. X, fig. 1, likewise from
the chalk, and to which there will be adduced reasons for believing that the fine speci-
men, in the collection of Sir P. de M. Grey Egerton, Bart. (ib. fig. 4), belongs. The
fossil jaw and teeth in fig. 14 determine the distinctness of the Coniosawrus from the
above-named fossil, as well as from all known recent Lizards.

The dentary bone contains from eighteen to twenty teeth; the anterior five or six
teeth are slender, slightly recurved, pointed, or laniariform; the rest progressively
increase in thickness as they are placed further back; expanding above the neck,
slightly compressed laterally, most convex inwardly, with an anterior border, which
is more prominent and curved than the posterior one: the anterior margin is further
characterised by a longitudinal groove on its outer side. Some of the posterior teeth
show a slight longitudinal indent near the posterior obtuse border; the last molar is
smaller and more obtuse than the others. The enamel is very finely wrinkled. The
teeth are closely and rather obliquely arranged; the long simple roots are anchylosed
to the bottom of the shallow alveolar groove, and to the inner side of the outer wall,

* Kove, ws, chalk; cavpos, lizard.

22 FOSSIL REPTILIA OF THE

and their excavations indicate the usual mode of succession and displacement: a few
alternate teeth have been shed.

The mode of attachment more resembles that which characterises the teeth in
Lacerta proper and other “ ccelodont” genera of the Lacertian tribe; but in the number,
proportions, and general shape of the teeth, the present species more resembles some
of the Iguanian tribe. The anterior coronal groove is continued to the anterior
margin of the crown, which it slightly indents in the larger teeth; but this is the only
approach to that complex structure which characterises the teeth of the typical
Tquande. Fig. 14 ais a magnified view of the crown of one of the anterior teeth;
and fig. 15 @ of one of the posterior teeth.

There is no existing species of the Iguanian or other herbivorous family, nor of any
of the ‘ pleurodont’ Saurians, with which the present chalk-fossil is identical ; nor can
I refer it to any of the established genera of Lacertilia. The absence of the cranium
and bones of the extremities, does not allow of any closer comparison with the Monitors,
Iguanas, or Scinks; but the characters of the teeth justify the consideration of the
fossil as the type of a hitherto undescribed genus and species, which I therefore
propose to call Coniosaurus crassidens, or the thick-toothed Lizard of the Chalk
formation.

The specimens represented in figs. 13, 14, and 15, are from the Clayton chalk-pit
near Brighton: a smaller portion of a lower jaw and a few teeth have been obtained
by Mr. Dixon from.the Washington chalk-pit near Worthing: and vertebra have been
found by Mr. Catt in the upper chalk near Falmer, during the cutting of the railroad
from Brighton to Lewes. ‘These are the only specimens of the genus and species that
have yet been discovered.

Genus, DOLICHOSAURUS,* Owen.

Dixon’s ‘ Geology of Fossils of the Tertiary and Cretaceous Formations of Sussex,’ 4to, p. 388.
Species, Dolichosaurus longicollis. (Tab. X, figs. 1, 2, 3, and 4.)

My esteemed friend the late Frederic Dixon, Esq., F.G.S., in the course of his
indefatigable inquiries respecting the fossils of the cretaceous period, obtained such
information relative to the unique specimen of the mutilated head and anterior thirty
six vertebre of the fossil Lizard from the lower chalk of Kent, in the admirable
collection of Mrs. Smith of Tunbridge Wells, figured in T. X, fig. 1, as left no doubt
in his mind that it formed part of the same skeleton with the chain of posterior
abdominal and sacral vertebre in the collection of Sir P. de M. Grey Egerton, Bart.,
M.P., F.G.S., and which is figured in the ‘ Geological Transactions,’ 2d Series, vol. vi,
pl. 39; and in the present work at T. X, fig. 4.

* Aodtyos, long, caupos, lizard.
Xx! ro) p

CRETACEOUS FORMATIONS. 23

Both specimens are from the same quarry or pit at Burham, in Kent, were found at
the same time, and there is good reason to suppose in the same block of chalk. It
appears, however, that they were disposed of by the quarrymen to different persons,
and ultimately found their way to the two collections of which they are now respec-
tively the ornaments.

Assuming, then, the two groups of vertebre to have belonged to the same skeleton,
and the conformity in shape and size of the vertebre and ribs favours the conclusion
which Mr. Dixon had drawn from the historical evidence, we may then enumerate fifty-
seven vertebree between the skull and the pelvis, supposing that none have been lost
between the end of the specimen in T. X, fig. 1, and the beginning of that in T. X,
fig. 4. Amongst existing Lizards this number of abdominal (cervical and dorsal)
vertebre is equalled only by those snake-like species (Pseudopus, Bipes, Ophisaurus)
which seem to make the transition from the Lacertian to the Ophidian reptiles: but
not any of such genera manifest so well-developed a humerus and scapular arch as are
indicated in T. X, fig. 1, at 51 and 53, or so complete a sacrum and pelvic bones as
are shown in fig. 4, at 62 and 63. Of those existing Lacertians which had the hinder
extremities as well developed as in the extinct species under consideration, the greatest
recorded number of vertebree between the skull and the sacrum is forty-one.*

Although the evidence relating to the discovery of the specimens (fig. 4 and fic. 1,
T. X) is such as to lead me to deem it highly probable that they form the anterior
and posterior moieties of the backbone of the same individual ; yet, as it does not
amount to absolute demonstration, the characters of the Saurian in question must
for the present be rigorously deduced from those parts which are unaffected by such
uncertainty. In this fit condition for scientific comparison must be regarded the frag-
ment of skull, and the chain of thirty-six vertebree imbedded in one block of chalk,
and represented in T. X, fig. 1. The most cautious and sceptical Paleeontologist must
admit, after scrupulous examination of the specimen, that the jaws and the portion of
vertebral column, which are accurately figured in the plate, have belonged to one and
the same animal, having been subject to no greater amount of dislocation than is
represented at the twenty-fifth vertebra for example, and in the position of some of
the ribs. Viewing the slight extent of displacement of any of these parts in the fossil,
it is very improbable that the scapular arch (51) should have been subjected to any
considerably greater degree of displacement; and taking, also, into consideration the
gradual diminution of the vertebrae, as they extend forwards from the place of the
scapular arch in the fossil, at the eighteenth or twentieth vertebree, to the cranium,
and the remarkable and striking difference in the shape and size of, the pleurapophyses
(vertebral ribs, p/., pl.) in those anterior vertebrze, I am led to conclude that the position
of the remains of the scapular arch (51) in the fossil was, in relation to the vertebral

* According to the table in Cuvier, Lecons d’Anat. Comp. i (1836), p. 221, e. g. in the Seincus ocellatus.

24 FOSSIL REPTILIA OF THE

column, its true position in the skeleton of the living reptile, and that the vertebrze
anterior to it answer to those which are called cervical by Cuvier, in the existing
lizards which have four well-developed extremities.

The artificial character of the ‘cervical’ vertebree of anatomy is more obvious in
the Lacertine Sauria than in most other vertebrates. Cuvier, who has assigned the
precise number of such vertebra to several species of Lacertians, in his ‘Table of the
Vertebre of Reptiles,* does not define their characters. He merely observes that
“they have inferior crests like the anterior dorsal vertebree.” t

With regard to the Monitor (Varanus) Cuvier affirms, in another work,{ that the
“inferior crest distinguishes the cervical from the dorsal vertebra ;”’ but he admits
that the first three of these dorsal vertebree have an inferior tubercle. Proceeding
next to speak of the American Monitor (J/onitor proper, or Zejus) he says,— Les
vertébres cervicales, déterminées par les fausses cOtes antérieures, sont au nombre de
huit, c’est-a-dire qu il y a six paires de ces fausses cdtes.”§ This number of so-defined
cervicals is found in the Iguanians, Basiliscs, true Lizards, Geckos, Anolises, Agamians
and Stellios. But Cuvier admits that two if not three of the last of these cervical
vertebree, although their false ribs (pleurapophyses) do not reach the sternum, are
embraced by the scapular arch, and concur in the formation of the chest: if these be
accordingly subtracted, the number of cervicals will be reduced, Cuvier says, to five.
In the ‘Table of Vertebree’ above cited, only four cervicals are allowed to the Iguana,
Basilisc, the banded Gecko, Anolis, Agama, and the Levantine Stellio. There is a dif-
ference, however, in the number assigned to some of these species in the table in the
‘Ossemens Fossiles.’||_ But all these discrepances depend on the inconsistent cha-
racters that hitherto have been assigned to the cervical vertebree of Lizards.

Recognising the artificial nature of such a group of vertebre, I believe that their
character, which must needs be arbitrary, would be most easily determined, and,
therefore, most convenient in its application, which should be founded on the absence
of sternal ribs (hamapophyses) : according to which character the vertebra that first
was joined to the sternum by sternal ribs would be reckoned as the first “ dorsal,”
and all anterior to it as “cervical vertebre.” This arbitrary character would agree
with that by which the cervical vertebre are, in point of fact, defined in the human
subject and mammalia generally.

In the fossil Lacertian, however, which forms the more immediate subject of this
description, there is no indication of a junction of the vertebral rib (pleurapophysis) by
a sternal rib (hemapophysis) with a sternum (hzemal spine), and I can only compare
the cervical region of the spine with that in existing Lacertians, in so far as relates to

* Lecons d’Anat. Comp. 1, (1835,) p. 220. +
{ Ossemens Fossiles, 4to, vy, pt. u, p. 284. $
|| Tom. cit. p. 288.

CRETACEOUS FORMATIONS. 25

the vertebra situated between the skull and the scapular arch. The number of
vertebrae so situated in modern Lacertians is usually five, and rarely exceeds six: in
the Dolichosaurus it was seventeen. In modern Lacertians the bodies and neural arches
of such cervicals are scarcely inferior in breadth to the succeeding vertebre, and
commonly surpass them in depth by reason of the largely developed inferior spinous
processes. The short anterior pleurapophyses are usually thick, broad, and expanded
at their extremities, or are “ hatchet-shaped” (Cyclodus, Tiliqua, Scincus). Besides the
superior number of the cervical vertebra in the Dolichosaurus, they exhibit a more
decided decrease of size as they approach the head: the pleurapophysis of the third or
fourth vertebra is short, almost straight, and very slender: that of the eighth or ninth
vertebra is also very slender, and but a little longer: those of the three succeeding
vertebre progressively, though slightly, increase in length, but the vertebral ribs
do not exhibit their normal length until the seventeenth or eighteenth vertebra : the
pleurapophysial character of these eighteen or twenty anterior vertebrae is much
more like that of the same vertebre in the Ophidian than in the existing Lacertian
reptiles: and there is no trace of any of the vertebral ribs having supported sternal
ribs, or having been attached by these to a sternum. The slender anterior ribs
increase in length, however, more gradually in the Dolichosaurus than in Serpents.
The occipital region of the fossil skull, with the atlas and dentata, have been too
much crushed to allow of their structure being accurately determined and compared:
the first tolerably entire vertebra appears to be the fourth from the head: the expanded
back part of the neural arch receives the contracted fore part of that arch of the fifth
vertebra: the base of the neural spine is slightly expanded posteriorly. In the fifth
and succeeding vértebree, the anterior articular processes look upwards, the posterior
ones downwards, and they are simple as in ordinary Lizards, but rather longer and
more slender. The thin base of the neural spine extends along the middle of the
summit of the entire arch; the sides of which slope downwards and outwards more
gradually, i. e. do not curve outwards so suddenly as in the /guana and Cyclodus. The
short convex diapophysis (d) supporting the rib is developed from the side of the fore
part of the centrum beneath anda little behind the anterior zygapophysis. I excavated
the chalk beneath the seventh vertebra, and exposed a short compressed ‘ hypapo-
physis, or inferior spine projecting downwards from the middle of the hinder half of
the centrum. ‘The ribs are hollow, as in the Cyclodus* and in Ophidians. The long
pleurapophyses of the twentieth and succeeding vertebre are more compressed than in
the Iguana and Cyclodus: they are less regularly or gradually curved ; the comparatively
straight middle portion after the first slight bend is too constant in the ribs of the
fossil not to be natural: this shape of the ribs indicates the abdomen to have been

* The vertebral ribs (pleurapophyses) are probably hollow in other Lacertians, but I cite only the
genus in which I have found them so in the present comparison,

26 FOSSIL REPTILIA OF THE

more compressed, as the number of vertebrze shows it to have been longer than in the
Iguana or Cyclodus. The twenty-sixth vertebra is dislocated: the two following are
turned upon their side and expose the under part: here the inferior spine has
disappeared: the surface is smooth, slightly punctate, gently concave lengthwise,
convex transversely. Figure 2 gives a direct side view of the best-preserved ramus
(the left) of the jaw: below, in outline, of the natural size; above, magnified.
The extent and upward curve of the coronoid piece (31) most resembles that in the
Varanus (Cuvier, loc. cit. pl. 16, fig. 8¢); but in this genus it is relatively shorter than
in the Dolichosaurus, and in other recent Lacertians it is still shorter and more pyra-
midal in shape. The extent of the surangular (30), and its length behind the coro-
noid, are Lacertian characters : but the outer surface is divided by a longitudinal ridge
or angle into an upper and a lower facet, the upper one being slightly excavated :
the enamelled crowns of the last four teeth show a simple obtuse shape; they are
chiefly remarkable for their small proportional size. The two dentary bones meet at
an acute angle; that on the right side joins a surangular piece which is con-
tinued back to near the articular surface. Allowing a symphysis of the ordinary
lacertian proportions, the length of the under jaw may be estimated to have been
four centimeters (one inch seven lines), or equal to between four and five dorsal
vertebrze. One of the vertical columelliform bones is preserved on the left side of
the cranium.

Parallel with the eighteenth, nineteenth, and twentieth vertebree le the remains of
a broad, thin, and flat bone (51), with a smooth emargination, and a rough or slightly
granulated surface. As the broad, thin, and anteriorly emarginate scapula of the
Iguana presents a similar surface, I conclude the part in the fossil marked 51 to be
scapula; and the short, thick, subcylindrical, hollow bone (53), slightly twisted and
expanded at both ends, to be the shaft of the humerus: it is shorter in proportion to
its breadth than in the existing Lizards, and probably supported a shorter fore-arm and
fore-foot ; the whole limb being therefore perhaps more formed for swimming than in
the Monitors and Iguane.

The ball-and-socket structure of the vertebrz is better adapted to sustain the
body on dry land than the biconcave structure; but the modern Crocodiles, the
Amblyrhynchus or marine lizard of the Gallopagos Islands, the Salamander, and even
the Lepidosteus amongst fishes, prove it not to be incompatible with aquatic habits.
The Dolichosaurus, with a proceelian type of vertebrate structure, and amongst the
earliest reptiles that manifested such structure, may well have been a good swimmer
and frequenter of the ancient ocean of its epoch, as well as a crawler on dry land.
Although the articulations of the vertebree must have limited if not prohibited rotation
or inflection of the spine in the vertical direction, the extent of lateral flexuosity is
considerable; the double curve of the fore part of the vertebral column, preserved
in fig. 1, being, if not the natural one assumed in the last struggles of the dying

CRETACEOUS FORMATIONS. 27

animal, that which the vertebral joint freely allowed in the dead carcase before it
became fixed in the chalk-mud.

Assuming that the specimens fig. 1 and fig. 4, T. X, give the natural length
of the neck and trunk of the Dolichosaurus, to which trunk the size of the anterior
caudal vertebra indicate a long and strong tail to have been appended, the progress
of the long and slender Dolichosaurus through the water would be by flexuous and
undulatory lateral movements of the entire body, like those of a water-snake or eel.

The specimen fig. 1, T. X, demonstrates that this proccelian Lizard of the cretaceous
period had a smaller head and a longer, more slender and tapering neck than any
known existing species of the Lacertian order of Reptiles.

The hinder moiety of the trunk-vertebree, with part of the pelvis and root of the tail,
fig. 4,—which, from the correspondence of size, shape and structure of the vertebre,
I refer to the Dolichosaurus, and from the evidence above given, corroborated by the
disposition of the parts in the chalk-matrix, I believe to be part of the same skeleton
as the anterior moiety, fig. 1, T. X—includes twenty-one abdominal, two sacral, and
five caudal vertebre. They have been exposed by the removal of the chalk from
their inferior or ventral surfaces, the operation having been commenced from the oppo-
site side of the block from that at which the exposure of the part of the skeleton in
the other portion of the same block of chalk has been effected. The bodies of the
vertebrze and the ribs show the same disposition and slight degree of dislocation as in
the specimen. The ribs have been pressed by the weight of the surrounding chalk, as
the soft parts yielded and became decomposed, close to the sides of the vertebrze, but
with scarcely any further dislocation; and the vertebree, maintaining the close articu-
lations of their cup-and-ball surfaces, continue, with not more deviation from the
straight line than a slight flexuosity, like that shown by the last six vertebrz in the
moiety of the skeleton in T. X, fig. 1.

The under surfaces of the vertebree exhibit the same smooth, imperforate, longitu-
dinally concave, transversely convex surfaces, as in the anterior dorsals of the last-
described specimen: as in that specimen, also, they are longer in proportion to their
breadth than in the Monitor (Varanus ?) figured by Cuvier,* or than in the Jyuaza,
Cyclodus and Tiliqua : the diapophyses rise by a shorter base than in the Jgwana: in an
Australian Zi/iqua I find the under surface of the centrum with two vascular perforations
towards its fore part, which are not present in the Dolichosaurus, nor in many of the
existing Lacertians. LKach diapophysis forms a short rounded tubercle, immediately
below the base of the anterior zygapophysis; and the simple, slightly expanded head
of the rib is excavated to fit the tubercle. In the degree of compression and expan-
sion of the proximal portions of the ribs, and in their curvature, the present precisely
corresponds with the preceding portion of the skeleton of the Dolichosaurus ; and it is

* Ossem. Foss., y, pt. ii, pl. 17, fig. 23.

28 FOSSIL REPTILIA OF THE

obvious that the natural form of the abdomen must have been deep and narrow, like
that of the Water-Snakes (/Hydrophides).

The length of the last two abdominal vertebre slightly decreases: a short, slender,
nearly straight and pointed pleurapophysis projects outwards from the diapophysis of
the last abdominal (lumbar) vertebra with which it has become anchylosed. The
pleurapophyses of the next two vertebre are equally confluent with the diapophyses,
but are rather longer and much thicker than those of the preceding vertebra: they are
also slightly expanded and truncate at their ends; they determine by these proportions
the ‘sacral vertebrz,’ which thus agree in number, as in general structure, in the
Dolichosaurus with those in existing Lacertians. ;

Part of the bodies of the two sacral vertebre has been destroyed, but evident traces
of the persistent cup-and-ball articulation between them remain. In the Scincoids
the bodies of the sacral vertebrae become anchylosed together. The extremities of the
sacral pleurapophyses come into contact in the Dolichosaurus, but do not coalesce: the
second sacral vertebra presents a ball to the first caudal, as in existing Lacertians, not
a cup, asin the modern Crocodilia. On the right side of the specimen the hinder half
of the iliac bone extends backwards, projecting freely a short way behind the second
sacral pleurapophysis, as in some modern Lacertians (Cyclodus, e.g.). On the left side
a part of the ilium is preserved, which extends to the acetabulum. A portion of the
expanded ischium is likewise preserved, and the distal half of the left femur extends
back in a right line from the position of the hip-jomt. The length of the entire femur
could not have exceeded three centimeters, or fourteen lines; it thus agrees in its
relative shortness with the humerus in fig. 1, 53, and accords with the idea that
the Dolichosaurus was more aquatic in its habits than the modern Lacertians, most of
which have longer proportional humeri and femora. The femur of the Dolichosaurus
had a medullary cavity. The under surface of the first two caudal vertebre is im-
pressed by a median, longitudinal, shallow canal, bounded by two slight ridges,
diverging posteriorly in the second caudal to the tubercles (hypapophyses) that have
supported the hamal arch; these tubercles are close to the posterior articulation. A
part of the spine of this hemal arch is preserved nearly in its true position.

The foregoing comparisons show that all the general characters of the Lacertian
type of the vertebrate skeleton are presented by the Dolichosaurus: they are most
modified in the cervical region, where the Ophidian type is rather followed in the
number and size of the vertebree, and in the size and shape of the ribs: a less decided
approach, but one still indicating an affinity to the Ophidians, is made by the unusual
leneth of the slender trunk, which includes, from the skull to the sacrum, not fewer
than fifty-seven vertebree, and is not less than eighteen inches in length. The smallness
of the head accords with the long and slender proportions of the neck, and must have
added to the snake-like appearance of this early example of proccelian lizard. But the
complete and typically Lacertian organisation of the scapular and pelvic arches, and

CRETACEOUS FORMATIONS. 29

of their locomotive appendages, prove that the Dolichosaurus was more strictly a lacer-
tine Saurian than the existing genera, Pseudopus, Bipes and Ophisaurus, which effect
the transition from the Lizards to the Snakes.

Tribe, NATANTIA.
Genus, MOSASAURUS.

The history of the discovery by Major Drouin, in 1766, of the gigantic marine
lizard called by Conybeare Mosasaurus, together with an account of the nature of the
formation in which its remains occur, are fully given by Cuvier, in his ‘ Recherches
sur les Ossemens Fossiles,’ tom. v, pt. i, pp. 310—320. The largest species of Mosa-
saurus is calculated to have been at least twenty-five feet in length, and derives its
name from the locality on the banks of the Meuse, near Maestricht, where the newer
cretaceous deposits occur in which its remains were found. The finest and most
perfect skull of the animal was discovered in the quarries at St. Peter’s Mount.
Camper saw it in 1785, in the house of the Rev. Dr. Goddin, canon of the chapter of
Maestricht, and writes:—‘“In this the greater part of both the upper and under
maxillary bones is entire, and a bone, with small teeth, belonging to the palate; by
which it appears, the animal had not only teeth in'the jaw-bones, but also in the
throat, as several fishes have, but which are never found in the mouth of crocodiles ;”*
and Camper naively expresses his surprise that notwithstanding all his endeavours to
convince his friends, he “never could prevail upon them to adopt his opinion, that
these bones belonged to the physeteres or respiring fishes.” In fact, neither the
physeter nor any other cetacean or respiring fish, have teeth on the palate any more
than the crocodiles. M. Adrien Camper, the son of the great anatomist, first pointed
out the affinities of the Mosasaurus to the Monitors and Jguana,t in which latter genus,
as in Amblyrhynchus, small teeth are present on the same bones, viz., the pterygoid,
in which they occur in the Mosasaurus. ‘The large fossil skull of the Mosasaurus was
yielded up by the Canon Goddin to the French army, after the capture of Maestricht
by the forces of the Republic in 1795, and it was transported to the Museum of the
Garden of Plants at Paris, where it still remains. M. Faujas St. Fond, who, in his
capacity as Commissary for the Sciences of the “ Army of the North,” transacted the
transfer of the famous specimen, gives the following account of its discovery :—

* Philosophical Transactions, 1786, p. 444.

+ Ina letter to M. Cuvier, in the ‘Bulletin de la Société Philomathique,’ Fructidor, An. vin (1790) ;
and in the ‘ Journal de Physique,’ Vendemiaire, An. ix (1791). See also his ‘Mémoire sur quelques
parties moins connues du squelette des Sauriens Fossiles de Maestricht,’ in the ‘Annales du Muséum d’Hist.
Nat.,’ tom. xix (1812), p, 215.

30 FOSSIL REPTILIA OF THE

“In one of the great galleries or subterraneous quarries in which the cretaceous
stone of St. Peter’s Mount is worked, about five hundred paces from the entrance,
and ninety feet below the surface, the quarry-men exposed part of the skull of a large
animal in a block of the stone which they were engaged in detaching. On this discovery
they suspended their work, and went to inform Dr. Hoffmann, surgeon to the forces at
Maestricht, who for some years had been collecting the fossils from this quarry, remu-
nerating the workmen liberally for the discovery and preservation of them. Dr. Hoffmann,
arriving at the spot, saw with extreme pleasure the indications of a magnificent
specimen ; he directed the operations of the men, so that they worked out the block
without injury to the fossil, and he then with his own hands cleared away, by degrees,
the yielding matrix, and exposed the extraordinary jaws and teeth, which have since been.
the subject of so many drawings,* descriptions, and discussions. This fine specimen
which Hoffmann had transported with so much satisfaction to his collection, soon,
however, became a source of much chagrin to him. Dr. Goddin, one of the canons
of Maestricht, who owned the surface of the soil beneath which was the quarry
whence the fossil had been obtained, when the fame of the specimen reached his ears,
pleaded certain feudal rights in support of his claim to it. Hoffmann resisted, and
the canon went to law. The whole chapter supported their reverend brother, and
the decree ultimately went against the poor surgeon, who lost both his specimen and
his money, for he was made to pay the costs of the action.” M. Faujas St. Fond,
the instrument of the more forcible and summary mode by which the French seized
upon the unique specimen, moralizes in his narrative of the robbery in the following
strain :—‘'The canon Goddin, leaving all remorse to the judges who had pronounced
the iniquitous sentence, became the happy and contented possessor of this unique
example of its kind. But justice, though tardy, comes at last.” (!) M. Faujas then
proceeds to narrate how, in the bombardment of the town, directions were given to
spare the suburb in which the famous fossil was understood to be preserved; and
how, after the capitulation, the French grenadiers discovered, seized, and bore off the
specimen in triumph to the commissarial residence; and concludes by a pean to the
“excellent soldiers who always knew how to appreciate and respect the monuments
of the arts and sciences.” ¢

The occurrence of remains of the dosasaurus in England was first noticed by,
Dr. Mantell, in a work entitled ‘The Geology of the South-east of England,” 8vo,
1833, in which woodcuts are given at p. 146, of a dorsal vertebrae, and of two
caudal vertebree, which were found in the upper (?) chalk, near Lewes. The body of
the dorsal vertebra is said to be “ about two inches long, and 1°4 inch high;” and the

* First by Buchoz, in his ‘Dons de Ja Nature,’ tab. 68; then by Faujas St. Fond, in plate iv of his
‘ Histoire Naturelle de la Montagne de St. Pierre ;’ afterwards by Cuvier, in his ‘Ossemens Fossiles,’ tom. v,
pt. 11, pl. xviii; copied by Buckland in the ‘ Bridgewater Treatise,’ pl. 20.

+ Tom. cit., p. 62.

CRETACEOUS FORMATIONS. 31

mutilated body of a vertebra of these dimensions, together with the two caudal ver-
tebre, form part of that collection which was sold by Dr. Mantell to the British
Museum. No proof is given that thege vertebrae belong to the same species as the
Mosasaurus Hoffmanni: the dorsal vertebre of the great Mosasaurus of Maestricit are
more than double the size of the one above cited, which, in the complete anchylosis of
the neural arch, would seem to have belonged to a mature individual of that cold-
blooded genus.

Subsequent discoveries of Mosasaurian Fossils in the English cretaceous deposits
have enabled the comparison with the specific characters of the J/osasaurus of Maes-
tricht, and of that from the Green-sand of North America, to be carried out satis-
factorily, especially in reference to the modifications of the teeth.

MOSASAURUS GRACILIS, Owen. Tab. VIII, figs. 1,2, and 3. Tab. IX, figs. 1, 2,
3, 4, and 5.

Dixon’s ‘ Geology and Fossils of the Tertiary and Cretaceous Deposits of Sussex.’ T. XXXIX.

Cuvier,” in his account of the great JJosasaurus of Maéstricht, which is entered
in the catalogues of M. v. Meyer and M. Pictet, under the synonyms J. Camperi
and MW. Hoffmanni, states that “all the teeth are pyramidal, a little curved, with their
external surface flat (‘ plane’) and divided by two sharp ridges from the internal surface,
which is round or rather semi-conical.” Messrs. Von Meyert and Pictet{ repeat
Cuvier’s description of the external characters of the crowns of the teeth; the one
says, ‘‘ihre Aussenseite ist eben’’—their outer side is flat or level; the other, “leur
face externe est plane.” My description{ of the teeth of the Maestricht Mosasaurus, in
which it is stated that “ their outer side is nearly plane, or slightly convex,” was founded
on an examination of the magnificent fossil skull in the Parisian Museum, the original of
Cuvier’s description ;—and the contour of the base of the crown of a maxillary tooth
of the Mosasaurus Hoffmanni given in T. IX A, fig. 7, is taken by accurate admeasurement
from a perfect specimen from the Maéstricht chalk: the enamelled crown of this tooth
was two inches (five centimeters) in length; the rest of the tooth was formed by the
enlarged coarse osseous fang; the total length of the tooth being four inches ten lines
(twelve centimeters and a half). Dr. A. Goldfuss, in his highly interesting and instruc-
tive description|| of the skull and teeth of the Mosasaurus Mazimiliani, accurately
describes and figures the finely dentated character of the two opposite longitudinal
ridges of the crown; but the feeble indications of angles observable in some of the

* Annales. da Muséum d’Hist. Nat., xii, 1808. Ossemens Fossiles, 4to, v, pt. ii, p. 322.
+ Paleologica, p. 219. { Traité élementaire de Paléontologie, ii, p. 63.
§ Odontography, 4to, p. 258. || Nova Acta Acad. Nat. Cur., t. xxi, p. 175.

32 FOSSIL REPTILIA OF THE

teeth, those of the upper jaw chiefly, of the Josasaurus Hoffmanni, do not bear out the
term ‘‘ polygonal” which he applies to the crowns of the teeth of that species, as well
as to those of his Mosasaurus Mazximiliani ; still less can I find these angles so con-
stant and regular as to divide the outer surface of the crown into five, and the ner
surface into seven facets; nor have I seen in any maxillary or mandibular tooth of
Mosasaurus Hoffmanni that near equality of extent and convexity between the inner and
outer surfaces of the crown, which Dr. A. Goldfuss describes (p. 178) and figures in
Tab. 9, fig. 4, of the memoir above cited. If that figure accurately represents a
maxillary tooth of the same species of J/osasaurus as the one described by Cuvier and
recorded by V. Meyer and Pictet under the name of JZ. Campert and Hoffmanni ; and
if the outer surface of the crown is ever flat or level, the range of variety between the
two extremes of flatness and convexity is greater than I have yet found in any of the
equally well-marked forms of teeth in other fossil reptiles.

The teeth in the specimens of upper and lower jaw of the species of Mosasaur from
the chalk-pit at Offham, Sussex, now in the Museum of Henry Catt, Esq., of Brighton,
and figured of the natural size in T. IX, fig. 1 and la, equally differ from the typical
form of tooth of the Mosasaurus Hoffmanni, and from those of the Mosasaurus Mazi-
miliant, T. IX. A, fig. 8: the outer surface of the crowns of the mandibular teeth of
Mosasaurus gracilis are more convex than those of Mos. Hoffmanni, and are less convex
than those of Mos. Maximiliani : not any of the teeth of Aosasaurus gracilis present that
angular disposition of the enamel which gives the polygonal form to the pyramidal
crowns of the teeth of the Jos. WMazximiliant. The lower jaw (T. IX, fig. 1) is more
slender, less deep in proportion to its length, than im the great Maestricht Mosasaur, and
the hinder teeth are relatively smaller and closer together; I have proposed, therefore,
to indicate the species by the name of MJosasaurus gracilis. The general form of the
crown of the teeth in Jos. gracilis is shown at 4, 6, and ¢, fig. 1 ; an exact contour of the
crown a little above its base is given at fig. 9, T. [IX4. The smooth and polished
enamel; the imequality of the outer and inner sides of the crown, such as it is; the
implanted fang of the tooth thickly coated by a coarse osseous cement; the general
anchylosis of the fang to the bony walls of the socket, which rise in a pyramidal form
from alveolar border of the jaw; all manifest the peculiar generic characters of the
great acrodont marine lizard, Mosasaurus. The maturity of the individual from which
the present specimen (fig. 1) has been derived, cannot be inferred from the solidifi-
cation and complete development of the anchylosed fangs of the teeth in a class of
animals in which those organs are repeatedly shed and renewed: the worn-out teeth,
m course of displacement, of the young crocodile, with their alveoli, present in
miniature all the senile characters of the corresponding teeth of the mature and aged
animal. If, however, the specimen of Mosasaur in question should be adult, it would
derive a well-marked specific character from its diminutive size as compared with the
Mosasaurus Hofmanni or Mos. Maximiliani ; being only one third the size of the latter,

CRETACEOUS FORMATIONS. 33

and one fourth that of the former species. But the characters of immaturity are not
manifested by the cold-blooded animals in their osseous and dental systems as they
are in the warm-blooded and higher organised mammalia.*

In all the teeth of the J/osasaurus gracilis in which the crown is broken, the
remains of the pulp-cavity are exposed in the centre of its base: but the immaturity
of the specimen is not demonstrated by this character; for, in the largest sized teeth
of the Mosasaurus Hoffmanni, even in one with a completely developed fang, measuring
with the crown nearly five inches in length, I have found a pulp-cavity extending
from the base of the crown into the expanded fang, but becoming almost obliterated
at the base of the fang. The cast of the crown of a still larger tooth of a Mosasaurus
from the green-sand of New Jersey, U-S., also shows the remains of a pulp-cavity at
its base. This cavity becomes filled in the fossil specimens with the matrix, which
is usually chalk; but sometimes the cavity, ike the air-chambers of polythalamous
shells, is filled with silex.

The number of teeth in each ramus of the lower jaw of Mosasaurus gracilis seems
not to have exceeded twelve. In Mosasaurus Maximilani they are reckoned at eleven; +
in Mosasaurus Hoffmanni at fourteen; and in this species they are placed closer
together than in the Jos. gracilis, as may be seen by comparing figure | of T. IX,
with that of the lower jaw given by Camper in the ‘ Philosophical Transactions’ for
1786, tab. xvi, which is copied by Faujas St. Fond, in pl. vi, of his ‘ Histoire de la
Montagne de St. Pierre. { The posterior teeth are rather smaller than the others in
Mosasaurus gracilis. At the fore part of the jaw the implanted and anchylosed base
of the teeth extends through about half the vertical diameter of the jaw; at the
posterior part of-the series the fangs sink into one third or one fourth the depth of
the jaw. The canal, which, as in the crocodile, extends below and along the-inner
side of the bases of the sockets and anchylosed fangs, is shown, filled by chalk, at
d, fig. 1. Traces of the vascular foramina along the outer side of ihe jaw are visible
in the right dentary piece, the outer side of which is exposed: the “splenial”
(“ opercular,” Cuvier,) element is shown at fig. 1, on the left ramus.

In the portion of the left superior maxillary bone (T. IX, fig. 1) all the teeth
are, unluckily, too much broken or abraded to give an idea of the precise form of
their crowns; they are rather more compressed at their base than in MWosasaurus
Hoffmann: : the posterior ridge is much less developed, and the whole of the posterior
longitudinally concave border is more transversely convex than in Mosasaurus Hoffmanne
or Mos. Maximilian. ‘There is as little indication of the angular or polygonal

* Dr. Goldfuss infers the maturity of his Mosasaurus Maximiliani from the characters, of which the
inadequacy is explained above. “Die vollstandige Verknocherung aller Theile, so wie die hiufige bemerk-
bare Aussfullung der Zahne beweisen, dass das Individuum seine vollstandige Ausbildung und mit dieser
nur die halbe lange des Mosasaurus Hoffmanni erreicht hatte.” (Loc. cit., p. 177.)

+ Goldfuss, loc. cit. p. 178. t Cuvier, loc. cit. p. 320.

5

34 FOSSIL REPTILIA OF THE

structure in these teeth as in those of the lower jaw; but the enamel shows some
longitudinal striations.

All the vertebrze of the J/osasaurus, according to Cuvier, are concave at the fore
part, convex at the hind part of their bodies; the convexity and concavity being
greatest on the anterior vertebree. The foremost of these are characterised by an
inferior process or “‘ hypapophysis,” developed from the middle of the lower surface of
the centrum: they have two transverse and four articular processes, and a long com-
pressed upper or neural spine. The centrum is longer than it is broad, and broader
than it is high: the terminal articular surfaces are transversely oval or reniform.
Such are the characters of the last cervical or first dorsal vertebre. The middle
dorsal vertebre are like these, but have no hypapophysis. Then follow vertebrz
which have no articular or oblique processes (zygapophyses), but have longer and
flatter transverse processes (diapophyses), and terminal articular surfaces of a pen-
tangular form, or of a triangular form with the base downwards (see T. VIII, fig. 5).
Next come vertebree with diapophyses and a pair of inferior processes (hypapophyses)
for the articulation of chevron-bones (hemapophyses); afterwards vertebrze without
transverse processes and with large anchylosed chevron-bones (heemapophyses) ; and
finally vertebree devoid of all processes whatever.

The vertebre discovered in the Kentish Chalk, with the jaws and teeth above
described, and of corresponding proportions to those parts which we observe in the
vertebrae of the MJosasaurus Hoffmanni, present all the generic vertebral characters of
that Lacertian genus, and correspond with the third and sixth kind, or with the posterior
dorsal and the anterior caudal vertebree, as defined by Cuvier. But the terminal articu-
lations of the centrum of the dorsal vertebree of MJosasaurus gracilis present a full oval
(not elliptical) form, the Jong axis of which is vertical and the great end downwards
(T. IX, fig. 4). The length of the centrum (2é., fig. 3), which is three centimeters
and a half, or one mch and five lines, exceeds the breadth; but this is equalled by
the height of the centrum. The diapophyses in fig. 2, d, are broken away; in fig. 3
it is uncertain whether the surface be a fractured one, or whether it is a natural
cavity for the rib; the analogy of MJosasaurus Hoffmanni favours the former view of
it. The neural arch (fig. 3, z) is anchylosed to the centrum, as in the larger species
of Mosasaurus. 1 can perceive only a feeble indication of zygapophyses, which shows
that the vertebra (figs. 2 and 3) comes from the posterior region of the back. The
neural canal (fig. 4, z) is small and triangular; a sharp longitudinal ridge rises from
the middle of its floor, and on each side of this there is a vascular canal descending
vertically into the substance of the centrum; this substance presents a coarse fibro-
cancellous texture; the areole extended longitudinally, and decreasing much in size
at the ends of the centrum. The outer surface of the vertebra is smooth ; the margins
of the anterior articular concavity are sharp.

The vertebra (fig. 2) shows, by the lower position of the diapophysis (@), that it

CRETACEOUS FORMATIONS. 33

comes from a more posterior position of the spine than that represented in fig. 3.
Fig. 5 gives a view of a caudal vertebra, which demonstrates another Mosasaurian
character in the anchylosis of the hemapophyses or chevron-bones to the centrum,
as in the posterior caudal vertebrae of Mosasaurus Hoffmanni; but the heemal canal
(fig. 4, e) is relatively wider, and the entire centrum is much longer than in the
corresponding kind of vertebra figured by Cuvier* or by Faujas St. Fond.

Three views of the body of a vertebra of the MJosasaurus gracilis, discovered
by the Rev. H. Hooper, M.A., distinguished by his geological researches in the
neighbourhood of Lewes and Brighton, are given in Mr. Dixon’s work above cited,
Tab. XXXIX, figs. 5, 6, & 7. This specimen is from the Sotheram Chalk-pit, near
Lewes.

From the genus Lezodon} (T. IXA, fig. 5**) the Mosasaurus gracilis (Ib. fig. 9)
differs, like the MJosasaurus Hoffmanni (Ib. fig. 7), in the inequality of the two sides
of the crown of the teeth, which are bounded or divided by the anterior and posterior
ridges. The MJosasaurus Maximiliani (Xb. fig. 8) differs from the genus Lezodon in the
polygonal character of the crowns of the teeth.

The interest which must be excited in the Naturalist and Palontologist by an
extinct Saurian, essentially organised according to the Lacertian type, but developed
on a scale surpassing that of the largest existing Crocodiles, and especially modified,
as it seems, for aquatic life, leads me to believe, that any additional facts tending to
complete its restoration will here be acceptable, although they may not have been
afforded by fossils from British strata. In the formations of the Cretaceous Period
in North America, answering in mineralogical characters to our Green-sands, though
probably contemporaneous with the newest chalk deposits of Europe, many fine
examples of MJosasaurus, of the species called by Goldfuss, Mos. Maximilian, have
been found, and the discovery affords a highly instructive instance of the coexistence
of particular forms of fossil Reptilia in remote parts of the earth, at. the same
geological epoch. In a series of remains of the MJosasaurus Mazximiliani, from a
Green-sand formation at New Jersey, United States, kindly submitted to my examina-
tion by Professor HENry Rogers, of Pennsylvania, I detected the basioccipital bone
of the cranium, which gave additional evidence of the Lacertian affinities of the
Mosasaurus, and new proof of the Cuvierian law of correlation of organic structures.
This basioccipital bone, which is figured in the ‘ Quarterly Journal of the Geological
Society, November, 1849, pl. x, fig. 5, was three inches and a half in length,
and four inches nine lines in extreme breadth. It resembled the centrum of the
“vertebra dentata” of the Crocodilia, in being convex behind and flattened in
front. The convexity formed the inferior and major part of the occipital condyle,
which must have been reniform, the angles being superior, and formed by the

* Cuvier, loc. cit., pl. xix, fig. 6, 4, B. + Loe. cit., pl. vit.
t Odontography, 4to, p. 261, pl. 72, figs. 1 and 2.

36 : FOSSIL REPTILIA OF THE

exoccipitals. The rough sutural surfaces for the articulation of these elements
were divided by a deep and narrow channel, which gradually expanded towards
the condyle. The anterior flat vertical articular surface of the basioccipital was
smooth, indicative of a persistent harmonia between it and the basisphenoid,
analogous to that which exists between the centrum of the axis and the odontoid
process. Two very thick and short exogenous processes (hypapophyses) diverge from
the under part of the anterior half of the basioccipital, and terminate in oblique and
slightly convex surfaces, irregularly pitted; they resemble the hypapophyses sent off
from the basisphenoid in the great Monitor (Varanus), against which the pterygoids
abut. This form and structure of the basioccipital of the Mosasaurus harmonizes
with the other indications of its Lacertian affinities. The basi-occipital in the
Crocodilia sends down a single hypapophysis.

No part of the organisation of the J/osasaurus is so little known as that of the
locomotive extremities. Cuvier gives copies of drawings which had been transmitted
to him of a portion of the scapula,* clavicle,t and coracoid,t of a portion of a long
bone, which he likens to the cubitus of a Monitor,) and of an os pubis,|| all of which
he believes to have belonged to the Mosasaurus.

The portion of the ulna would indicate, Cuvier remarks, that the J/osasawrus had
moderately elevated extremities ;4] but he adds that “ the bones of the fore and hind
feet, so far as they are known, would seem, on the contrary, to have belonged to a kind
of contracted fin, like that in the dolphin or Plesiosaur.** He, however, figures two
bones comparable with the two principal bones of the carpus of the Crocodile,t+ and
which one would scarcely expect to be associated with metacarpals and phalanges like
those of the Hzaliosaurs. And if the ungual phalanx, figured in pl. xx, fig. 21, of
the ‘Ossemen’s Fossiles,’ be rightly attributed to the Aosasaurus, it determines the
question in the negative, as to whether that Lacertian reptile had plesiosaurian
paddles ; the phalanx in question much resembles that in the British Museum (No. 384,
Mantellian Catalogue), which has been described as “ The Horn of the Jgwanodon.” The
phalanx represented in Pl. xx, fig. 5, of the same work, with almost flat articular
ends, must have belonged to a natatory form of foot; but as large Chelonians were
associated with the J/osusaurus in the Maestricht beds, it would be rash to conclude
that this phalanx absolutely belonged to the J/osasawrus. Cuvier, in fact, sums up
by admitting the hesitation which he feels in offering his conjectures as to the nature
of the extremities of the J/osasaurus, which were founded on the inspection of drawings

* Ossemen’s Fossiles, tom. v, pt. 2, 4to, pl. xix, fig. 9. + Ib., fig. 14.

de lby, fiosmllos § Ib., pl. xx, fig. 24. || Ib., pl. xix, fig. 10.

4 <<Il annoncerait que ses extremités étaient assez élevées.”’ (Ib., p. 336.)

** «Les os des mains et des pieds, autant qu’on les connait, sembleraient au contraire avoir appartenu
a des espéces de nageoires assez contractées, et plus ou moins semblables 4 celles des dauphins ou des
plesiosaurus.”” (Ib. p. 386.) +t Ib., pl. xx, figs. 4 and 5.

CRETACEOUS FORMATIONS. 37

only, for he says the immediate comparison of the bones themselves would hardly
suffice, so great is the diversity and so small the precision of the forms of those
bones in reptiles.*

M. Pictet, in the second volume of ge, ‘Traité Elémentaire de Paléontologie,’ 8vo.,
1845, terminates his brief summary of the characters of the M/osasaurus, by stating :—
“Les membres paraissent avoir été terminés par des nageoires aplaties,” (p. 62.)

In the collection of Saurian fossils submitted to me by Professor Henry Rogers
were some bones of the extremities, showing the Lacertian type of structure, and
agreeing in colour, petrified condition, and proportional size with the vertebre and
teeth of the Wosasaurus from the same Green-sand formation. They were too large to
be attributed to the Crocodilian species indicated by the vertebrae from the same
formation. I subjoin, therefore, a brief description of these interesting fossils which
appear to me to throw additional light on the structure of the locomotive organs of
the Mosasaurus.

The first of these bones gave the following dimensions :—

Feet. Inches.
Extreme length . ; : : : : : 2 8
Extreme breadth of the neat ol : : ; @ 0 8
Breadth of narrower end of the same bone Gapertect) : c 0 4i

The best preserved extremity of this long bone is expanded and subcompressed,
like the lower end of the fibula of the Varanus, one part of this extremity being pro-
duced into an obtuse angle. The extremity is smooth, slightly concave transversely
on one side, more irregular on the opposite side, with a thick prominent border
opposite to the produced angle. The shaft of the bone has an irregular full, oval,
transverse section with dense walls of concentric plates of bone, eight or nine lines
thick, surrounding a medullary cavity, one inch nine lines in diameter. The shaft
is very slightly. bent. The opposite extremity which gradually expands, preserving
the general form of the shaft, exhibits a strong longitudinal ridge of six inches in
extent, but which subsides before it reaches the articular end. Only a portion of this
end is preserved, which is slightly and irregularly convex.

The second long bone of the extremity yields the following dimensions :—

Feet. Inches.

Extreme length : 2 5
Breadth round the upper (?) seaealaaine snrfee 0 43
Depth of articulating surface 0 3f
Breadth of lower (?) end (imperfect) 0 3

This bone, therefore, equals in length the preceding, but becomes more attenuated
in the middle than any of the long bones in the existing Saurians ; one extremity is

* Loe. cit., p. 357.

38 FOSSIL REPTILIA OF THE

compressed, and terminates in a slightly convex, thick, smooth articular border:
Nine or ten inches below this, the shaft, shghtly increasmg in breadth and decreasing
in thickness, presents a thick, rough, and prominent ridge, three inches and a half in
length, apparently for the attachment of some strong muscle; behind this ridge the
shaft contracts to a diameter of one inch nine lines, and to a circumference of four
inches six lines. At ten inches from the distal end it increases in thickness, assumes
a trihedral form, with one edge produced and convex, subsiding above the articular
end, which is in the form of a simple convex condyle, not excavated for a trochlear
joint in the middle, but with an irregular branched impression or smooth groove at
that part: the articular surface extends upon the fore and the back part of the shaft,
about two inches six lines from the end, contracting posteriorly, and with a convex
border anteriorly above, where there is a shallow semilunar depression. There is a
very deep large hemispheric pit on each side above this condyle. There is no
medullary cavity in this bone. .

These two long bones are more like the tibia and fibula of the larger lizards than
the radius and ulna: there can be little doubt that they belong either to the leg or to
the antibrachium, but they differ too much in shape from any of the bones of those
segments in the larger lizards, with which I have been able to compare them, to
encourage me to hazard a positive determination. I should be disposed to ascribe
them, from their length and slenderness, to the hind leg. They are more Lacertian
than Crocodilian in their general character ; and they belong with great probability to
the Mosasaurus.

A metacarpal or metatarsal bone of the same reptile gives the following
dimensions :—

Feet. Inches.
Extreme length . : : : : : : : 2 1 8
Extreme breadth of the broader articulating surface or upper end 0 pied
Central depth of ditto . 2 : : : : : : 0 34
Breadth of lower end 0 3

The proximal or upper end is suddenly expanded, with an undulated or partly
convex partly concave articular surface, nearly flat, at right angles to the shaft; sub-
triangular with the angles rounded off, or reniform on account of the deep notch
posteriorly, below which there is a depression. A ridge is continued from the shaft
upon two of the angles, which gives a subhemispheric section of the shaft at six
inches from the head. Here a medullary cavity nine lines in diameter is exposed.
One half of the parietes of the middle third of the shaft of this bone is preserved,
which shows a continuation of the medullary cayity and the development of an
angular ridge from the shaft, which subsides about six inches from the distal end.
This end slightly expands into a simple convex condyle, with the articular surface

CRETACEOUS FORMATIONS. 39

irregularly grooved, and with a large deep hemispheric pit on one side above the
surface, but not on the other.

The above-described long bones were taken back by Professor Rogers to America ;
the followimg specimen he liberally permitted me to retain.

A metacarpal or metatarsal bone rather larger than the preceding, with the notch
at the proximal end much less deep. The angular border or ridge, continued from
one of the posterior rounded angles of the articular surface, quickly subsides ; that
from the other angle is contmued down from the middle of the shaft, giving it an oval
transverse section. ‘The fracture of the shaft, nine inches from the head of the bone,
exposes an oval medullary cavity, nine lines in the long diameter. The longitudinal
ridge is developed from the distal half of the bone, as in the former, and it terminates
in asimple convex condyle with the grooved sculpturing upon the articular surface, and
with the large deep hemispheric pit for a ligament, on one side of the trochlea, and
a large shallow notch on the opposite side.

The following two bones of the toes conform to the Lacertian type, and not to that
of the Hnaliosauria. The first is a proximal phalanx of a toe of apparently the same
Saurian as the bone last described. The proximal articular surface appears to have
been subcircular, very slightly concave, with a few shallow pits and grooves in the
middle, like those on the end of the metatarsal. The shaft gradually contracts, and
becomes more convex in front than behind; it subsides into a shallow depression
above the forepart of the distal trochlea, on each side of which there is a large and
deep ligamentous pit. Its dimensions are as follows :

Inches.
Extreme length 5
Breadth of upper articulating een 24
Depth of ditto 5 : 2
Breadth of lower articulating surface 13
2

Depth of ditto

The second specimen is a second phalanx of apparently the same toe; having an
expanded, concave, proximal, articulating surface, adapted to the distal surface of the
preceding bone; and terminated by an oblique broad convex trochlear articulation.
Its dimensions are as follows:

Inches
Extreme length 4 ; i ; 5 ; 3 : 5 3
Breadth of upper articulating eee 25
9

Depth of ditto : : :
Breadth of lower articulating surface ; 5 4 ; 5 F 2
Depth of ditto 1

On the highly probable supposition that the above-described long bones belong to
the Mosasaurus, they indicate the extremities of that gigantic lizard to have been

40 FOSSIL REPTILIA OF THE

organised according to the type of the existing Zacertilia and not of the Haahosauria
or Cetacea. But a foot so organised for crawling on land might, nevertheless, by the
webbed union of the large and long unguiculate claws, have been well adapted, like
the feet of the Amblyrhynchus and Alligator, for swimming; and the modifications of
the vertebral column, especially of the long and deep tail of the MWosasaur, clearly
prove it to have been more strictly aquatic in its habits than any known existing
lizard.*

The vertebra from the Chalk near Lewes (Tab. VIII, figs. 1 and 2) above alluded to,
which is the subject of the cut, No. 2, p. 146, of Dr. Mantell’s ‘Geology of the South-
East of England,’ is one of those posterior dorsal or lumbar vertebre, in which the
diapophysis (¢) arises from near the middle of the side of the centrum, and has a
depressed flattened form, at its origin, instead of the thicker subcompressed form that
characterises the same process in the anterior dorsal vertebrae. The specimen in
question is much mutilated ; both the neurapophyses, z, the diapophyses, ¢d, and part
of the left side of the centrum, are broken away; but the rarity of such evidences
of the Mosasaurian genus in our English Chalk, and the historical mterest attached to
this, which is one of the first specimens discovered, has induced me to give an
accurate figure of it in T. VIII, figs. 1 and 2, together with one of the homologous
vertebra of the Maéstricht species (figs. 4 and 5), which is preserved in the British
Museum. The specimen from Lewes presents the following dimensions :—

Inches, Lines.
Length of the centrum . 5 : : ; 5 ; 3 2 0

Vertical diameter of ditto
Transverse diameter of ditto .
Length of the base of the neural arch

aS ee

4
6
8

The neural arch, x, has completely coalesced with the centrum: it terminates
behind, about four lines from the convex articular end of the centrum. The marginal
circumference of that surface, fig. 2, has been worn away, but it evidently presented
a more obovate and less triangular figure than in the Wosasaurus Hoffmanni, fig. 5.
The fractured base of the diapophysis, shown at d, fig. 4, is situated lower than half-
way down the side of the centrum.

The two caudal vertebre (fig. 3) have been retained in natural juxtaposition in
the same block of Chalk. Both the neural (x) and heemal (4) arches have coalesced
with the centrum without any trace of the primitive sutures, the antero-posterior
extent of the neurapophysis is relatively shorter than in the more advanced vertebra,

* M. Hermann yon Meyer, in his comprehensive and useful summary of Fossil Remains, entitled

‘Paleeologica,’ Svo, 1832, classifies the Mosasaurus with the Plestosaurus, in the Order of Sauria,
characterised by fins. (‘‘Saurier mit flossartigen Gliedmass®n,” p. 201.)

CRETACEOUS FORMATIONS. Al

as is shown by fig. 6 as compared with fig. 4, and by the following admeasurements
of one of the caudal vertebree :—

Inch. Lines.
Length of the centrum : - 0 : ; . : 1 7
Vertical diameter of the convex end 1 5
Transverse diameter of ditto . 1 3
Length of the base of the neural arch 1 0
Length of the base of the hzemal arch 0 9

The hemapophysis (4) swells outwards at its origin, before it bends downwards,
backwards, and inwards to unite with its fellow in order to complete the arch. The
area or span of this arch has been considerable, as in the vertebra, fig. 5,T. IX, and
as it is in the Wosasaurus Hoffmanni: it is probable that the spinous process continued
from it had a corresponding remarkable length, but of this the fractured condition of
the specimen affords no proof. The lateral surface of the centrum is smooth, with
many small vascular perforations. There is a slight but well-marked rising above the
base of the heemapophysis, at d, which seems to indicate a last rudiment of the
diapophysis. A narrow vertical ridge (,) extends about two lines from the border of
the posterior convex surface, as if it were indicative of the limits of an epiphysis
which had formed that surface. The border of the anterior concave surface has been
worn or broken away. A linear impression gives also an indication of an epiphysis in
the dorsal vertebra of the Mosasaurus Hoffmanni. ‘The slight degree of concavity and
convexity of the terminal articular surfaces of the centrum in these vertebre is
characteristic of the genus. In their special characters, the small vertebrae from
Lewes correspond with the vertebra attributed to the Mosasaurus gracilis, which are
longer and more slender than those of the J/osasaurus Hoffmanni.

Genus.—LE1ODON, Owen.

‘Odontography,’ p. 261, pl. Lxxii, figs. 1 and 2.
‘ Report on British Fossil Reptiles,’ Trans. Brit. Association, 1841, p. 144.

The teeth from the chalk of Norfolk, surmised by Dr. Mantell, from “their
symmetrical, conical form, and other characters,” to belong to an unknown reptile, or
to a sauroid fish ;* and described and figured in my ‘ Odontography’t as character-
istic of a new genus of Mosasauroid Reptiles, under the name of Leodon,t presented

* Wonders of Geology, ed. 1839, vol. i, p. 339. + Vol. i, p. 261, pl. Ixxii, figs. 1 and 2.
t Aecos, smooth, odo%s, tooth.

A2 FOSSIL REPTILIA OF THE

the same acrodont type of dentition as in Aosasaurus and Geosaurus, but differed in
their closer arrangement and from the former, especially, in the shape of the crown, of
which the outer side was as convex as the inner side, the transverse section being an
ellipse with pointed ends, which latter corresponded with two opposite trenchant edges
dividing the outer from the inner side of the crown. This was covered by a smooth
enamel without any indications of minor ridges or facets: the apex of the crown was
sharp-pointed ; the body of the crown slightly recurved; and its base expanded into
a thick fang of a circular form, which was anchylosed to a short conical process of
the alveolar border of the jaw.

Deducing the generic dental characters of Mosasaurus from the magnificent
example of the jaws and pterygoid bones, which passed from Dr. Hoffmann’s
collection to that of the Canon Goddin, and ultimately to the Museum of the Garden
of Plants at Paris, the deviation in the teeth in question from the inequilateral facetted
character of the crowns of the maxillary and mandibular teeth of that specimen was
so great, as to lead me to infer that these teeth from the English chalk belonged to a
distinct genus of the same family of the Lacertine order; unless, indeed, they might
be pterygoid teeth of a species of Mosasaurus, distinct from the Mosasaurus Hoffmanni.
After a rigid comparison in reference to this question, I was led to the conclusion
that they were not pterygoid, but maxillary teeth, and I therefore described them
under the name of Leiodon anceps. The general results of that comparison, which
would have been out of place in a systematic Treatise of Teeth in general, will here
be requisite.

LEIODON ANCEPS, Owen. Tab. IX, 4.

‘Odontography,’ 1840, vol. i, p. 261; vol. ui, pl. 72; figs. 1 & 2,
Mosasaurts stenopon. Charlesworth. The London Geological Journal, 1846, p. 23.
pls. 4 and 6.

Baron Cuvier, after a close and accurate description of the pterygoid bones of the
great MJosasaurus Hoffmanni, concludes by stating, that “each of these bones seemed
to have supported eight teeth, which grew, became attached, and were replaced, like
the teeth of the jaws, but were much smaller."* They also differ from the jaw-teeth
by having their two sides less unequal in regard to their convexity ; the inner side is

almost as convex as that side of the maxillary teeth, but the outer side of the

* «<Cet os paroit avoir porté dans notre animal fossile huit dents qui croissoient, se fixoient et se

remplacoient comme celles des machoires, quoique beaucoup plus petites.’” (Ossemens Fossiles, tom. y,
pt. ii, p. 324, 4to, 1824.)

CRETACEOUS FORMATIONS. 43

pterygoid teeth is more convex than the nearly flat outer side of the maxillary teeth.
They resemble, in fact, in their transverse section, the lower maxillary teeth of the
Mosasaurus Dizoni. The alveolar border to which the pterygoid teeth are attached
in the MMosasaurus Hoffmanni, is moderately convex towards the cavity of the mouth;
the alveolar tract is relatively thicker or broader than on the jaws, and the germs of
the new pterygoid teeth appear almost like a second small row on the outer side of
that row which is in place, being less close to the teeth they are destined to replace
than they are in the maxillary series.

The teeth in question from the English Chalk, differed in the shape of their
crowns from the pterygoid teeth of the Mosasaurus Hoffmanni, and the alveolar
border to which they were attached, more resembled that of the dentary piece of
the lower jaw. In the smoothness of the enamelled crown, its compressed elliptical
form and trenchant borders, which, when magnified, presented a fine serration, the
teeth in question, approached to the characters of those of Geosaurus, as much as they
deviated from those of Mosasaurus. Both MWosasaurus and Geosaurus afford types of
the acrodont mode of dental attachment. Had only the teeth and portions of the
jaws of the Geosaurus been known they might have been registered, on such limited
evidence, as having belonged to a species of A/osasaurus distinct from the Josasaurus
Hlofimanm, and the Anatomist, SOEMMERRING, even supposed that the Geosaurus
might be merely the young of that species. But the differences in the shape of the
teeth are associated with differences in the structure of the cranium, of the sclerotic,
and, what is still more important, in that of the vertebree themselves, which are sub-
biconcave and contracted in the middle of the centrum. With these evidences,
therefore, of the importance of the differences indicated by different forms of the
teeth of the acrodont Sauria, one may be justified in the expectation that the Lezodon
will prove to be a genus alike distinct from both dJ/osasaurus and Geosaurus, and,
as probably tending to fill up the hiatus that divided those genera in the series of
Acrodonts, as it was known to Cuvier.

The additional evidence which has been received in elucidation of this highly
interesting family of Saurians, since the publication of my ‘ Odontography,’ has
tended to confirm the conclusions stated in that work relative to the Le/odon anceps.
The Mosasaurus of the Green-sand Formations in North America, has been satis-
factorily shown in Professor Goldfuss’s Memoir, to be a species distinct from that of
the Cretaceous Deposits at Maestricht. The maxillary teeth show the same generic
characters, the two sides being unequal, but with specific modifications. The ptery-
goid teeth are ten in number on each pterygoid bone, attached in like manner to an
alveolar border, which is convex both downwards and outwards: all the crowns of
these pterygoid teeth had been unfortunately broken off and lost.

Mr. Charlesworth has described and figured in the first part of the ‘London
Geological Journal,’ a portion of jaw-bone, with five teeth, of the Lezodon anceps, which

44 FOSSIL REPTILIA OF THE

he states to have come into his possession from “one of the numerous chalk-pits on
the Essex side of the Thames ’—the side on which the county of Norfolk lies; and it
appears that the teeth described and figured in my ‘QOdontography’ are not only
specifically identical, but once formed part of the same specimen, with that which he
has since figured. This may well be, for in the mass of materials which I had been
collecting for six years previous to the publication of my ‘Odontography’ I found the
drawings, which are engraved in Pl. 72, figs. 1 and 2 of that work, marked ‘from the
chalk of Norfolk,’ without any other memorandum, and I feel obliged to Mr. Charles-
worth for having publicly supplied in 1846, what my memory in 1840 failed to do,
viz., the reference to the individual to whom I had been indebted in 1835 for the
loan of the originals of those drawings.

With regard to the question of the nature and affinities of the Zezodon, the
additional evidence which the figures published by Mr. Charlesworth afford, is of
value. The teeth in that specimen can only be referred to the genus Mosasaurus, as
characterised by Cuvier and Goldfuss, on the supposition that they are ‘ pterygoid teeth.’
But, in an extent of an alveolar tract of seven inches, and including five teeth, that
tract is slightly concave lengthwise, instead of being convex: and it wants the
horizontal platform extended to the outside of the teeth in place, and supporting the
nidus of their successors, which characterises the pterygoid bones.

In my ‘Odontography, I have briefly noticed one of the most common conditions
of fossil teeth, in which the pulp-cavity has not been obliterated by calcification of the
pulp itself in the lifetime of the animal. Thus, in the section on the teeth of the
Ichthyosaurus, it is described in the following passage. “The remains of the pulp,
after the formation of the due quantity of dentine, became converted, as in the
pleodont lizards, by a process of coarse ossification, into a reticulate, fibrous, or
spongy bone; but it continued open at the crown after the basal part of the tooth was
thus consolidated, as is shown in the longitudinal section, (Pl. 73, fig. 8,) wherein a
is the pulp-cavity, filled with crystallized spath, 4 the ossified pulp at the base of the
tooth.” p. 279. In fig. 2*, Tab. IX, 4, is reproduced Mr. Charlesworth’s figure of the
mass of similar siliceous spath, that, in like manner, filled the uncalcified part of the
pulp-cavity of the tooth of the Lezodon anceps. Although I should not have called this
“a very unlooked for condition of the interior of the tooth,” I concur with the Editor
of the ‘London Geological Journal’ in his hypothesis of the precipitation of the
siliceous matter from a fluid. But, at the same time, I am fully conscious how trans-
parent a veil such an hypothesis is to our ignorance as to the precise conditions of the
precipitation of such matter in the interior of fossil teeth, im the medullary cavities of
fossil bones, and in the closed chambers of many polythalamous shells. The only
wonder connected with the fact illustrated in T. IX, 4, figs. 2 and 2%, is, that any
Geologist should deem it an unlooked for or extraordinary one. ;

I have described and figured some small detached crowns of the teeth of the Lezodon,

CRETACEOUS FORMATIONS. 45

from the Chalk-pits of Sussex, in my friend Mr. Dixon’s Geology of the Tertiary and
Cretaceous Deposits of that County, Tab. XXXYII, figs. 10, 11, and 12. One of the
finest and most characteristic teeth of this genus was discovered in the Chalk, during
the cutting of the Brighton and Lewes Railway : it is figured in T. IX, 4, figs. 6 and 6*,
and is now in the fine Collection of Henry Catt, Esq., of Brighton.

OrpER.—CROCODILIA.
Genus —Crocopitus? Tab. XV.

In the Museum of Mr. Saull, F.G.S., there is a small block of green-sand from the
County of Sussex, containing several parts of a small, and apparently very young
crocodile. The portion of the upper jaw, and of the right ramus of the lower jaw,
T. XV, figs. 1 and 2, demonstrate the crocodilian shape and mode of implantation
of the teeth, which have thick, subconical, obtuse crowns, and present proportions
most resembling those of the Goniopholis crassidens.* The alveolar border of the jaw
has a similar wavy outline, and so differs from that in the Gavials and Teleosaurs, in
which the alveolar border is straight. The sockets of the teeth, which are distinct at
the anterior half of the jaws, run together at the posterior half, as in the Alligators
and the young Crocodiles of the existing species. Several bony scutes are preserved,
as, e. g., at ss fig. 3; none of which show the tooth-like process at one angle, which
characterises many of the scutes in the Gonzopholis: and as there is not a single
centrum, or body of a vertebra to give the characters of the articular ends of that
part, I am unable at present to determine the species. The femur, 65, is longer and
more slender in proportion to the ischium, 63, than in the Nilotic or Indian Crocodiles:
and the tibia, 66, and fibula, 67, are longer in proportion to the femur. This species
evidently had the hind legs proportionably more developed than in existing Crocodila,
and better adapted for swimming,—a character which is observable in the Teleosaurs
and some other Crocodiles of the secondary formations. At the same time it should be
remembered that, in the Green-sand Formations of New Jersey, vertebra of two species
of Crocodiles or Alligators have been discovered by Professor Henry Rogers, con-
structed on the same proccelian type as those of existing species. See ‘ Quarterly
Journal of the Geological Society,’ January, 1849, p. 380, pl. x.

* Report on British Fossil Reptiles, Trans. Brit. Association, 1841, p. 69.

46 FOSSIL REPTILIA OF THE

Genus.—POLYPTYCHODON, Owen.

‘ Odontography,’ 1840, vol. ii, p. 19, pl. 72, figs. 3 and 4.
‘Report on British Fossil Reptiles,’ Trans. Brit. Association, 1841, p. 156.

Having described in the preceding pages the fossil remains of the Class REPTIL1A,
from the Chalk-formations, which, as in the case of the Mosasauroids, are either
referable or most nearly allied to species long known as characteristic of those
Formations; or which, as in the case of the Chelona, and the smaller Lacertilia with
proeceelian vertebrze, are nearly allied to the Turtles and Lizards of the present day :
I next pass to the consideration of those fossils which indicate a greater deviation
from modern types of the order, and which are either new, or comparatively new to~
Science.

In collecting the materials for my * Report on British Fossil Reptiles’ I soon found
that among the evidences of that class in the Cretaceous Deposits of England, a large
species of Saurian was indicated by thick conical teeth, having the general characters
of the teeth of the Crocodile, but distinguished by the more regular circular transverse
section of the crown, the absence of two opposite larger ridges, and the presence of
numerous close-set, narrow, longitudinal ridges, continued, In some specimens, of
nearly equal length to within a short distance of the apex of the crown, but in more
specimens, of unequal length; a comparatively small number only of the ridges
extending to near the apex: a few of the largest specimens of the teeth presented
fewer and more minute ridges, and a greater degree of smoothness and polish of the
enamel. Without venturing to say how far this latter character in the largest tooth
might be due to age, there was a general adherence of all these teeth toa type of
form and structure, which differed to such a degree from the type of any other recent
or fossil teeth, as to induce me to signify such difference by applying a generic name
to the extinct Reptile to which they belonged; and I accordingly described and
figured them in my ‘Odontography’ under the name of Polyptychodon,* in reference
to their many-ridged or folded exterior.

Some of these teeth in their size, and most of them in their general aspect, re-
semble at first sight the teeth of the great Sauroid fish Hypsodon, of Agassiz, which are
also found in the chalk: but those of Polyptychodon may be distinguished, generally,
by the greater solidity of the crown, and the conformity of the structure of the dentine
with that of the Crocodiles and Plesiosaurs: the ridges also on the exterior of the
crown of the Hypsodon’s teeth are alternately long and short, and end abruptly at
different, but commonly greater distances from the apex of the tooth than in Polyply-

* Vol. ii, p. 19: from wodvus, many, 77vé, a fold, odvds, a tooth.

CRETACEOUS FORMATIONS. AT

chodon, the interspaces between the longer ridges widening as they approach the
apex. The teeth of the Polyptychodon never offer any approach to opposite trenchant
edges of the crown: but this part, presenting throughout its extent a transverse section
of an almost circular form, (T. XI, fig. 7, Tab. XIV, fig. 3,) is slightly and regularly
bent lengthwise, and is invested with a moderately thick layer of true enamel, of
which substance the ridges are wholly composed, the surface of the outermost layer
of dentine being quite smooth, (Tab. XIV, fig. 4). The teeth of the Polyptychodon
may be distinguished at once from those of the MMosasaurus or Pliosaurus by the
absence of the less convex, or almost flattened facet of the crown, which is divided by
strong ridges from the remainder of the crown.

POLYPTYCHODON CONTINUUS, Owen. Tab. XIV, figs. 4, 5, 6.
‘Odontography,’ vol. ii, p. 19.

The first evidence of this species was a single tooth, which was discovered by
W. H. Benstep, Esq., of Rock Hall, near Maidstone, September 16th, 1834, in what
is called the ‘ Trigonia-stratum’ of Shanklin Sand, in the Kentish Rag Quarries near
that town, this stratum being a member of the Lower Green-sand Formation. The
tooth in question (T. XIV, figs. 5 and 6) has a crown upwards of three inches in length,
and one inch four lines in diameter across its base. The compact dentine has been
partially resolved by decomposition into a series of superimposed thin hollow cones,
fig. 6, and the short and wide conical pulp-cavity is confined to the base, and
beginning of the fang, which has been broken away. ‘The cavity of the crown of the
tooth in Hypsodon would seem to have been always much larger, as it is in many other
predatory fishes in which the teeth are more rapidly shed and renewed than in the
Crocodilian Reptiles. In the Collection of Henry Catt, Esq., of Brighton, is preserved
the crown of a nearly equally fine specimen of the Polyptychodon continuus, from the
Chalk of Sussex: this specimen is figured of the natural size in T. XIV, fig.4. A portion
of the ridged enamel has:scaled off, exposing the smooth surface of the dentine which
it protected. The teeth of this species of Polyptychodon differ from those supposed to
have belonged to Pozhilopleuron, in the ridges of the crown being more numerous and
close set, and in the transverse section being circular instead of elliptical.

GiGANTIc FossiL SAURIAN FROM THE LOWER GREEN-SAND AT HYTHE.
Tabs. XII and XIII.
‘Proceedings of the Geological Society of London, June 16th, 1841.’

I propose to describe these remarkable and highly interesting fossils under the
present section, on account of the identity of the Formation in which they were dis-
covered, with that of the tooth of Polyptychodon continuus above described, and because

AS -FOSSIL REPTILIA OF THE

no other teeth have as yet been found in the Cretaceous Series to which the fossils in
question could be referred. These are at present, however, the sole grounds of the
probability that such teeth and bones of a large Saurian, may have belonged to the
same genus.

The bones about to be described, are unquestionably the remains of a Saurian of
marine habits, but most probably of the Crocodilian order, as gigantic as the
Cetiosaurus or Polyptychodon, but, in the absence of any associated parts yielding the
dental and vertebral characters, not certainly referable to any known genus. They
were discovered, in 1840, by H. B. Mackeson, Esq., of Hythe, in the Green. sand
Quarries, near that town, and include portions of the coracoid, humerus, and ulna, of
the iliac, ischial, and pubic bones, a large proportion of the shaft of a femur, parts of
a tibia and fibula, and several metatarsal bones, four of which exhibit their proximal
articular surfaces. The remains occupied a space in the quarry, of about fifteen feet
by twelve, where it would seem that a proportion of the skeleton of this gigantic
Saurian, including the pelvis with one hinder extremity, and a part of the fore-limb
had been exposed. In consequence of the absence of vertebre and teeth, the present
observations will be limited to indicating the characters by which these remains differ
from previously known extinct genera of Saurians. In the first place, as the femur
and other long bones have no medullary cavities, but a central structure composed of
coarse cancelli, it is evident that the animal of which they formed part was of marine
habits, and did not belong to the Denosauria ; but the best-preserved bone being a
femur, this circumstance, independently of the size and shape of the metatarsals, at
once negatives the idea that these remains belonged to the Cetacean order, whilst the
form and proportions of the metatarsals equally forbid their reference to any other
Mammalian genus, or to the Reptilian order Hnaliosauria. ‘The cells of the cancellous
tissue are about a line in diameter: the compact outer crust or wall of the bone is
from four to five lines in thickness. In the recent state, the cells of the cancellous
structure of the marine Saurian’s bones were doubtless filled with a fluid oil, as in
the similarly coarsely cancellous bones of the Cetaceans, and thus the specific gravity
of the animal would be nearly accommodated to that of the fluid in which it
principally, if not exclusively existed.

Femur.—vThe portions of this bone, T. XII, fig. 1, secured by Mr. Mackeson
include about the two distal thirds, excepting the articular extremity ; its length is
2 feet 4 inches; its circumference in the middle, or smallest part of the shaft, is
15 inches 6 lines, and at the broken distal end, 2 feet 5 inches. These dimensions
prove that the animal was equal to the most gigantic described Iguanodon.* If the
supposition of the proportion of the femur which has been preserved be right, this
bone differs from that of the Jguanodon, not only in the want of a medullary cavity,

* The length of the largest femur yet obtained of this Saurian is 4 feet 6 inches, its smaller
circumference 1 foot 10 inches.

CRETACEOUS FORMATIONS. 4g

but also in the absence of the compressed process which projects from the inner side
of the middle of the shaft. ‘The bone also expands more gradually than in the femur
of the Jyuanodon, and the posterior part of the condyles must have been wider apart
in consequence of the posterior inter-condyloid longitudinal excavation being longer
and wider. The middle part of the shaft of the femur is subcompressed, with a
nearly quadrilateral contour of the transverse section, the line bounding the outer
side being less convex and longer than that which circumscribes the inner side of the
bone: the anterior surface is flatter than the posterior one. The anterior and outer
surfaces meet at a more marked angle than do any of the others; the angle being
formed by an obtuse ridge. The concavity of the posterior surface begins about
6 inches above the broken distal end of the present fragment, and gradually increases
in both width and depth as it descends. The width of the inter-condyloid groove at
the fractured distal end is 5 inches 4 lines. The same admeasurement in the largest
Iguanodon’s femur gives 2 inches. The convex ridge leading to the inner condyle is
more prominent than the outer one; and on the tibial side of the mner ridge there is
a second slight concavity. On the anterior surface of the distal end of the femur
there is a broad shallow depression of the surface, corresponding to the deeper one
behind, and there is not the narrow and deep groove which characterises the corres-
ponding part of the femur of the Jguanodon. The texture of the distal end of the
bone presents the same coarse cancelli as occupy the middle of the upper part of the
shaft, but with a thinning of the outer laminated compact crust. The following
are admeasurements of the bone not given in the above description :—

Inches. Lines.

Transverse diameter of the middle of shaft . : : 5 5 6
Antero-posterior or lesser diameter of ditto : c 3 9
Greater diameter of the distal end . : ¢ 12 0
Smaller diameter of ditto at middle of the iia onndeiedat groove 5 0

Tibia and Fibula.—The portion of a tibia, T. XIII, fig. 1, Tr, which has been pre-
served, is compressed near its head, and the side next to the fibula is slightly concave.
The longest transverse diameter is 8 inches 9 lines, and the two other transverse
diameters at right angles to the preceding give respectively 3 inches 3 lines, and
2 inches 6 lines. The bone soon assumes a thicker form, its circumference at about
one third from its proximal end being 16 inches 6 lines. The compact laminated
outer wall of the bone is 4 lines thick. The cancelli occupying the central portion of
the bone are arranged in a succession of layers around a point nearest the narrower
end of the transverse section. Lower down the tibia again becomes compressed, and
towards the distal end the transverse section exhibits the form of a plate bent towards
the fibula, and its narrowest transverse diameter is 24 inches.

The portion of the fibula, T. XIII, fig. 1, Fr, is 1]4 inches long. In the middle it is
flat on one side, slightly concave on another, and convex on the two remaining sides.

~
/

50

FOSSIL REPTILIA OF THE -

An outline of a section of this part is given at Fig 1. It presents the same can-

Outline of an imbedded metatarsal of the Polypty-

choaon.

Scale 23 inches to a foot.

cellous structure as the tibia, but the
concentric arrangement of the layers
of cells ismore exact. ‘Towards the op-
posite end of the bone the concave side
becomes first flat, and is then produced
into a convex wall, terminating one end
of a transverse section of a compressed
and bent thick plate of bone. The long
diameter of this section is 6 inches 6 lines
at the end of the fragment ; 4 inches from
that end it measures 5 inches 6 lines:
the shorter diameter of the compressed
bone at the same part is 1 inch 10 lines;
an outline of the transverse section of this
part is given in Fig. 2. Of several Jong
and strong bones, which from their form and relative size
represent metatarsals, there are considerable portions
of four, detached, with their proximal articular surfaces
preserved ; a fifth, wanting the articular extremities ;
and two others longitudinally split and imbedded in a
mass of the Green-sand matrix; these latter exhibit the
characteristic inequality of length of the Crocodilian
metatarsals, and are probably the innermost and second
metatarsals of our present gigantic Saurian.

The innermost and smallest measures one foot in
length; the adjoining metatarsal two feet. Their position
in the rock shows that the part of the skeleton had been
separated through decomposition before they were per-
manently imbedded, the proximal articular extremities
being 3 inches apart, but on the same transverse line.

The outline of the larger of these imbedded meta-
tarsals is subjoined at fig. 3; its transverse diameter at
a, is 8 inches, at 6, 4inches 5 lines, and at c, 6 inches.

The smaller metatarsal is more contracted at the
shaft which presents a triedral contour : the diameter
of its greater end is 5 inches; that of the narrow part
of the shaft is 1 inch 11 lines; its compact outer crust
is between one and two lines thick ; all the rest of the
substance presents a cellular texture, the cells having
a diameter of one half to two thirds of a line.

CRETACEOUS FORMATIONS. 51

Proximal end and section of shaft of a metatarsal of Polyptychodon !

Proximal end and section of shaft of a metatarsal of Polyptychodon !

Of the detached metatarsals I subjoin outline sketches of the articular end, and the
transverse section of the shaft for facilitating the comprehension of their form and
their comparison with.other remains. The chief of these is the proximal portion of a
metatarsal bone 15 inches, 6 lines in length. Figure 4 is the contour of the articular
end, which is slightly convex at the smaller side, nearly flat at the wider one, and
with a very irregular superficies, being pitted all over with depressions admitting the
end of the little finger, these depressions at some parts of the circumference of the
articular end being continued into as broad grooves, which soon subside to the level of
the surface of the shaft. Figure 5 is the outline of the fractured end, nine inches from
the articular end of the same bone: the angle indicates a ridge which runs obliquely
down the bone towards the middle of the surface, and subsides near the broken end,
fifteen inches down the shaft. The dotted line indicates the thickness of the lamimated
wall, which gradually becomes less compact, and encloses a coarse cancellous structure.
The outer surface of the bone is smooth.

Figure 6 gives the contour of the articular end of a proximal portion of a metatarsal
bone 11 inches long. The articular surface is pitted with cavities, as in fig. 4, the size
of the same, as if for a coarse ligamentous articulation: the cavities are continued
into grooves at 44. Figure 7 gives the contour of the broken surface, six inches

52 FOSSIL REPTILIA OF THE

below the proximal end: the whole thickness of the bone, within the compact outer
wall, being occupied by a coarse cancellous structure.

Fig. 8. Fig. 10.

-----~-----------5]

"

410.
1
1
\
\
'
H
i}
1
1
!
'
i
‘
1
i)
1
i
}
Se

Fig. 9. Fig. ne

a!
cp
H

H

1

;

H

H

t

Proximal end and section of shaft of a metatarsal bone of Polyptychodon.

Of a fragment, 12 inches long, of the proximal portion of a metatarsal bone,
figure 8 gives the contour of the articular end; and fig. 9 of the fractured end of the
shaft; the dotted outline indicates where the outer crust of the wall prevented an
exact figure of the contour being made; but the shaft of the bone seemed to have been
flat on that side.

A fourth fragment of a long bone measured 10 inches in length. Figure 10 gives
the contour of the proximal articular end of this bone (the outer wall having scaled
off). Figure 11 is the contour of the fractured end of the shaft, 5 inches beyond the
articular end. It is occupied by a coarse cancellous structure throughout.

There remain to be noticed some less perfect fragments of huge flat bones im-
bedded, or indicated by their impressions, in masses of the Green-sand Rock. In three
of these I recognise the ilia, ischia, and pubes: they are broader than in the Crocodiles,
but would be conformable to the Crocodilian type, if the cartilaginous parts of some of
those bones in the recent species were ossified: by this greater extent of ossification
of the large fossils in question, the pubis and ischium approach somewhat to the
Plesiosaurian type. The ilia are imbedded in the same block of stone: they are flat,

CRETACEOUS FORMATIONS. 53

nearly straight, and become gradually wider and thicker towards the end attached to
the sacrum: of these bones a portion 25 inches long is preserved of the one, (T. XII,
fig. 6,) and 20 inches of the other: the broadest end of the longer portion measures
across 10 inches. In a second block, the mesial extremities of the pubis and ischium
are preserved. The exposed surface of the pubis is principally convex, but becomes
concave towards the opposite or median margin: it measures across at its broadest
part 13 inches; the length of the fragment preserved is 17 inches. The diameter
of the corresponding expanded extremity of the ischium is 9 inches: its expanded
extremity is obliquely truncated ; that of the pubis is rounded. In another block the
expanded extremity of the opposite pubis is preserved; it measures 14 inches across,
and is 22 inches in length.

In a third large mass of rock, the fragment of an enormous, apparently sub-
quadrilateral flat bone, is exhibited, which most probably belongs to the pectoral arch,
and, in that case, must be the coracoid bone, T. XII, fig. 5, p. The length of this
fragment is two feet, its greatest breadth 17 inches: its thickness varies from 3 to
5 inches. On one side there is a slight submedian ridge, from which the surface
slopes away with a gentle concavity.

The breadth of this bone indicates the great development of the muscles destined
for the movement of the fore-leg, whence it may be inferred that the anterior
extremities were more powerfully and habitually used in progressive motion than in
the Crocodiles. In the existing species of this family, the anterior extremities are
used chiefly for the support and movements of the body on land; they are applied to
the sides of the chest when the animal swims, which is chiefly effected by the actions
of the strong and long vertically compressed tail. The lateral movements of the fore-
legs being much restricted, the coracoid bone and the muscles arising from it are
comparatively slender. In the Enaliosauria, where the fore-legs are converted into
paddles for swimming, the coracoids are vastly expanded, both for the increased
strength of the shoulder-jommt and the increased surface for the attachment of the
muscles, which effect the lateral movements and the stroke of the paddle-shaped limb
upon the water. We may infer, therefore, that the anterior extremities of the present
gigantic Crocodilian were, by some webbed modification of the hand, better adapted,
and more energetically used for swimming than in the existing Crocodilians.

The shaft of a long bone somewhat similar to, but shorter and more slender than
the femur, and crushed, is preserved with that of a smaller bone, tapering more
gradually to one end, in the same block of stone: these are figured in T. XIII, fig. 2;
the larger bone is probably the humerus, H, the smaller one the ulna, v.

Other less intelligible fragments of the long bones of the same great Saurian are
represented in T. XII, figs. 2,3, and 4; and in T. XIII, figs. 2and 4. Fig. 3 probably
shows two of the metacarpals in the same block of stone.

The principal parts above described are preserved in the British Museum, to

54 FOSSIL REPTILIA OF THE ©

which’ Institution they were liberally presented by their discoverer H. B. Mackeson,
Esq. _ They were mutilated in the attempt to disencumber them of the massive blocks
of the matrix in which they were imbedded, and: are less characteristic than when I
took the’ foregoing Gescription and sketches of them on the spot where they were
found. E

it has been shown that the texture of the femur, tibia, fibula, and fe other larik
bones, i is conclusive against the identity of the Saurian of the Hythe Lower Green-
sand with the great ambulatory Dimosaurian reptiles, viz., Iguanodon and Megalosaurus,
the former discovered in the Lower Green-sand at Maidstone, and both species also in
the Wealden and Oolite Formations; there then remains to be considered its relation-
ship with the Enaliosaurians, the Crocodilians, the Mosasaur, and Poikilopleuron. ©

The length, thickness, and indication of condyles in the femur, and the length,
thickness, and angular form of the metatarsals, place the Plesiosaurs, and, @ fortiori, the
Ichthyosaurs, out of the pale of comparison.

The superior expanse of the pubis, and the broad coracoid (?) with the form of the
femur, and the gigantic proportions of all the bones, forbid a reference of the Saurian
in question to any subgenera, recent or extinct, of the Crocodilian Reptiles, of which
the bones of the extremities were previously known.

If it were true that the JJosasaurus had locomotive extremities in the form of
flattened paddles, like the Plesiosaurus, the identity of our present Reptile with the
Maéstricht species would be at once disproved, by the unequivocal remains of the
metatarsal bones, which indicate a form of foot, corresponding, as far as the skeleton
is concerned, with that of the Crocodile: and if, as is most probable, the metatarsals
of the Lacertian type from the Green-sand of New Jersey appertain to a J/osasaurus,
the metatarsals from the Green-sand at Hythe differ from them in size, shape, and the
absence of any medullary cavity.

With regard to the Crocodilians, the extinct genus which most closely agrees with
the characters of the bones of the Hythe Saurian is that which I have named Cetio-
saurus, the vertebrze of which have been found in the Wealden and Oolite formations,
and the long bones of which are devoid. of a medullary cavity. Unfortunately no
vertebra referable to Cetiosaurus has yet been discovered in the Cretaceous deposits.
It is possible that the teeth on which the genus Polyptychodon has been founded may
belong to Cefiosawrus ; but hitherto such teeth have not been discovered in the strata
where the remains of Cetiosaurvs are common.

The gigantic Saurian discovered by M. Deslongchamps, in the Oolite at Caen,
and which he. has named Pothilopleuron Bucklandit, yields for comparison with the
Hythe Saurian the femur, fragments of the tibia, fibula, and metatarsal bones.

In the form of the condyles of the femur, and their posterior intervening channel,
the Hythe Saurian resembles the Poikilopleuron more than it does the Iguanodon;
but the large medullary cavity in the femur of the Poikilopleuron distinguishes it as

CRETACEOUS FORMATIONS. 55

much as it does that of the Iguanodon from the Hythe Saurian. The medullary canal
is described as being very great in the tibia of the Poikilopleuron.*

The absence of vertebrze and teeth in the Hythe specimen prevents the establish-
ment of a comparison of these instructive parts of the skeleton of the two extinct
Saurians, and the question of the dental characters of the Poikilopleuron remains in
the same doubtful state as it is left by M. Deslongchamps, who describes and figures
a detached large Crocodilian tooth from the Oolite near the village of Allemagne, as
corresponding in size with the remains of the Poikilopleuron.t

M. Deslongchamps conceives it may be useful to make known these teeth at the
same time with his Poikilopleuron, leaving to. subsequent discoveries the determination of
the truth or otherwise of the approximation. For the same motive I have prefixed to
my account of the Hythe Saurian a description of the teeth of a gigantic, and hitherto
unknown Saurian from the Green-sand at Maidstone, and shall append to it an account
of similar teeth from the Chalk Formation in Sussex, Kent, and Cambridgeshire.

Since the bones of the extremities of Mr. Mackeson’s large reptile from the Green-
sand afford sufficient evidence of their distinctness from the tallying parts of any
previously described Saurian genus, and since we have evidence as satisfactory of an
equally gigantic Saurian genus from the teeth which occur in the same Formation, it
may be allowable, for the purposes of the present record, to regard both the bones and
the teeth as parts of the same animal. Until, therefore, further evidence is obtained,
showing the Hythe skeleton to have been furnished with differently-formed teeth, or
the teeth from the Maidstone Green-sand to have been associated with a differently
constructed skeleton, I shall apply to the Hythe fossil the name of Polyptychodon,
under which the genus of gigantic Saurian, hitherto known only in the Green-sand and
Chalk strata, was first indicated.

POLYPTYCHODON INTERRUPTUS, Owen. Tab. X, figs. 7, 8, 9; Tab. XI; Tab. XIV,
figs. 1 and 2.

‘Odontography,’ vol. ii, p. 19, pl. 72, fig. 4; and in Dixon’s ‘Geology and Fossils of the
Tertiary and Cretaceous Deposits of Sussex,’ p. 378.

The majority of the specimens of the teeth of this species have been found in
the middle and lower Chalk or Chalk-marl: one large tooth of this species has been

* «Le canal medullaire etait fort grand; lepaisseur du tissu compact, en d, est d’environ 0™ 013.”’
(Deslongchamps, ‘Sur le Poikilopleuron,’ 4to, p. 55.)

“Dans ce tiers inférieure, le femur est un peu plus étendu transversalement que d’avant en arriére.”
(Deslongchamps, loc. cit.)

+ “On a trouvé, 4 diverses epoques, dans les carriéres du Village d’Allemagne de grandes dents,
toujours isolées, offrant tous les caracterés de celles des Crocodiles. J’en figure une, pl. vi, (de grandeur,

56 FOSSIL REPTILIA OF THE

discovered by the Rev. Peter Brodie, M.A. F.G.S., in the upper Green-sand at Barnwell,
near Cambridge, and. a few other specimens have been obtained by James Carter, Esq.
from the Green-sand of another locality, near Cambridge.

The fine examples of teeth figured in T. XI (with the exception of fig. 8) were
discovered in 1847 by Mr. PotTER, of Lewes, in the lower bed of Chalk-marl, just
above the Green-sand, in the vicinity of that town. They formed part of as many as
from twenty to thirty teeth of nearly the same size which were scattered at no great
distance from each other. No part of the jaw-bones could be detected; and as the
teeth are fully formed, and some of them retain their long fangs, it may be inferred
that they were originally implanted freely, like the teeth of the Crocodile, in loose
sockets, and have dropped out as easily, after the decomposition of the gums and
other soft parts. The crown is about two sevenths the length of the entire tooth,
and its enamelled striated coat terminates by an abrupt and well-defined border; the
fang continues to expand to about its middle part, whence it gradually contracts to an
obtuse end, which is perforated by the entry to the pulp-cavity. The general shape of
the crown agrees with that of the Polyptychodon continuus ; the difference is shown by
the greater proportion of the ridges which stop short of the apex of the crown, espe-
cially on the convex side of the tooth. In using the term convex or concave as applied
to the crown, allusion is made to the slight bend of crown in the direction of its axis.
Around the entire basal part of the crown the ridges are close together: their inter-
spaces are only the clefts that separate them. On the concave side of the tooth a
large proportion of the ridges extend nearly to the apex, as is shown in T. XI, fig. 1;
but on the convex side a greater number extend only one third or two thirds towards
the apex, these shorter ridges alternating with the longer ones, between which, there-
fore, at the apical part of the tooth, there are intervals of flat tracts of enamel. The
apex of the tooth is rather obtuse. On one side of the crown there is a long ridge,
towards which contiguous shorter ones have a convergent inclination. The long fang
of the tooth is covered by a layer of smooth cement. The dentine is compact, and
corresponds in microscopic structure with that of the crocodile’s teeth. In the frac-
tured specimens of the teeth from Lewes, the dentine had become resolved into super-
imposed conical layers, as in the larger tooth from the Green-sand of Maidstone: this
effect of long interment is represented in figs. 1, 3, 5, and 7, of T. XI. There is no
trace of the absorbent action excited by pressure of a successional tooth in any of
these specimens of teeth.

Although the detached state of the above-described teeth with well-developed fangs
would have suggested and sustained the inference that they had been implanted like

naturelle, fig. 8, reduite au quart, fig. 9.) Elles ont interiurement une cavité conique; leur surface
couverte d’email jusqu’A une certain distance de leur base, est ornée des stries en relief, longitudinales, de
longeur inégale, dont deux seulement, situées aux extremités du méme diamétre, arrivent jusqu’a la
pointe.” (p. 80.)

CRETACEOUS FORMATIONS. 57

the teeth of the Crocodile, direct evidence to that effect had not been obtained at the
time of the publication of my ‘ Report on British Fossil Reptiles ;’ and it has been
objected that the mode of fixation of the teeth of the Polyptychodon might have
been the same as in the Mosasaurus, and that those teeth might belong to a second
extinct genus of gigantic Sea-lizards. The specimen, however, which is represented
of the natural size in T. X, fig. 3, inclines the balance in favour of the Crocodilian
affinities of the Polyptychodon, by proving that its teeth were implanted in distinct
sockets, and not anchylosed to the summits of processes of the jaw, as in Mosasaurus
and Leiodon. In the figure cited, taken from an unique specimen of part of the lower
jaw of the Polyptychodon interruptus discovered in the lower chalk-deposits of Kent, and
now in the collection of Mrs. Smith, of Tonbridge Wells, the letter 6 shows the
smooth cement-covered cylindrical base, and ¢ the enamelled conical crown; s is an
adjoining vacant alveolus, from which a tooth similar to that in place has slipped out,
like the teeth from the Lewes Chalk-marl. The crown of the tooth in place is rather
longer in proportion than in most of the detached teeth from Lewes; and it may,
therefore, indicate a certain inequality in the length of the crowns of the teeth in the
same jaw, as in the Crocodiles, and it may have answered to the tooth which is some-
times called, on account of its greater length, the “‘ canine tooth” in the Crocodile. The
socket anterior to the one with the completed tooth contains the germ of a young
tooth, e, and shows that the teeth succeeded each other from the same sockets as in
the modern Crocodiles.

The crown of a much larger tooth of the Polyptychodon interruptus, which is figured
in Tab. IX, figs. 16 and 17, was found near Valmer, during the cutting of the Lewes
railway, and_is now in the museum of Henry Catt, Esq., F.G.S., of Brighton. It
shows well that alternate and interrupted character of the longitudinal ridges of the
enamelled surface which distinguishes the present species, but the ridges have been
more worn down, especially towards the apex, in Mr. Catt’s specimen, than in the one
originally figured in my ‘ Odontography.’* The body of the crown consists of a hard
compact dentine, partly resolved in the specimen by incipient decomposition into
superimposed hollow cones, like the similarly-sized tooth of the Polyptychodon continuus
from Mr. Bensted’s Green-sand “ Iguanodon” quarry at Maidstone.t The cylindrical
case of the tooth is excavated by a wide conical pulp-cavity with an obtuse summit,
into which a small central process projects from the base of the crown (fig.17). The
enamel is very thin at the base of the crown.

Figure 8 in Tab. XI, is the crown and part of the base of a still larger tooth of
apparently the same species of Polyptychodon obtained by Mr. Catt in October 1850, from
the grand and picturesque chalk-pit, or rather chalk-cliff, at Houghton, near Arundel.

* Odontography, pl. Ixxii, figs. 4, 4’,
+ Ib. fig. 3, and ‘Report on British Fossil Reptiles,’ p. 156.

D

58 FOSSIL REPTILIA OF THE

One or two of the long ridges of this tooth are more than usually prominent, and most
of the shorter ones are fainter than usual; but I cannot regard those differences in any
other light than as individual varieties. The pulp-cavity at the base of the tooth, filled
up in the specimen by the white chalk, appears to have been unusually large, as if the
specimen had been in an incompletely developed state. If this were the case, it must
have come from a very large specimen of the present species of extinct reptile.

To such a specimen must have belonged the anterior end of the left ramus of the
lower jaw, (T. XVI) discovered in the Burham Chalk-pit, in Kent, and now in the
choice and instructive Collection of J. Toulmin Smith, Esq. The fragment is upwards
of a foot in length, but contains only three alveoli, and corresponded, probably, to the
premaxillary part of the upper jaw of the same animal. The first socket, s 1, is nearly
three inches from the fractured end of the jaw, and two inches from the larger socket,
s 2, behind it; the third socket, s 3, is closer to the second. These are filled up by the
chalk, the teeth having fallen out. The outer surface of the jaw is convex and promi-
nent; a solid mass of the bone extends horizontally inwards from the anterior socket,
to form the symphysis, which seems to have been ossified, with the opposite ramus.
The substance of the bone has the same coarse cancellous tissue as that of the portion
of the smaller jaw of Polyptychodon, (T. X, fig. 7); and, as it shows a similar inequality
in the intervals of the alveoli, it may be concluded to belong to the same genus, if not:
species, of extinct Crocodilian reptile. The present fragment indicates an individual
as large as the great Mosasaurus, the skull of which was discovered in the Maestricht
Chalk.

Fine specimens of crowns of the teeth of both species of Polyptychodon, T. X, figs.
8 and 9, have been obtained by James Carter, Esq., M.R.C.S., of Cambridge, from the
Upper Green-sand near that town, and also at Horn-sea, in the same county. These
specimens present a darker colour than those of the chalk, by reason of the modifi-
cation of their matrix. The ridges are remarkably well defined on the enamel; the
dentine presents the same well-marked division into layers, cone within cone, as in
the Chalk specimens, and that from the Shanklin sand near Maidstone. The crown
of one of the specimens of the Polyptychodon interruptus from the Cambridge Green-
sand, equals in size that of the Polyptychodon continuus, discovered by Mr. Bensted in
his quarry near Maidstone.

OrveR. HNALIOSAURIA,
Genus.—PLESIOSAURUS, Conybeare.

Besides the teeth which, according to their form and structure, were referable to
the different genera. and species of Reptilia above described,—viz. to Raphiosaurus, —

CRETACEOUS FORMATIONS. a9

(T. X, fig. 53) to Coniosaurus, (T. IX, fig. 14a;) to Mosasaurus, (ib., fig. 1;) to Leiodon,
(T. IX A, fig. 1 ;) and to Polyptychodon, (T. XI and T. XIV,)—we now, for the first
time, in our progressive researches, descending through the strata which indicate
the changes which the part of the earth’s surface forming England has undergone,
meet with teeth of different and peculiar type, remarkable, viz., for their length and
slenderness, and with a circular transverse section, not subcompressed or with opposite
trenchant margins, as in the Gavials of the Tertiary deposits. The tooth represented
of the natural size in T. IX, fig. 8, is a good example of one of those of the form in
question. Its enamelled crown, if entire, would exceed an inch and a half in length,
yet it is but half an inch in diameter at its base; the crown is slightly curved
and tapers gradually to a point; the enamel presents some slender but well-defined
longitudinal ridges of different lengths, and none of them extending to the apex. The
fang or root is cylindrical, smooth, and covered by a thin cement. The tooth above
described was obtained from the Scaddlescombe Chalk-pit, near Lewes, Sussex.

A similar specimen, rather more fractured, T. 1X, fig. 10, was found in a Chalk-pit
at Southeram, Sussex.

A smaller tooth, (T. IX, fig. 9,) of the same type, but with more numerous longi-
tudinal ridges, seems to indicate a different species. This specimen was also found
at Southeram.

If satisfactory and abundant evidence of the nature of the extinct reptile to which
the above-described teeth belong had not been obtained from Secondary Formations of
a more ancient date than the cretaceous ones, the Comparative Anatomist would have
inferred, and correctly, the generic distinction of the Reptile to which they belonged ;
but he could-have had no suspicion of the truly extraordinary nature of the animal, the
entire race of which, after flourishing under a variety of specific forms from the epochs
of the Muschelkalk and Lias, finally perished at the time of the deposition of the
Chalk.

The anatomical description of the Plesiosaurus, discovered and restored by
ConyYBEARE and De 1a BeEcue, will be reserved for the Monograph descriptive
of the fossil Reptiles of the formations in which its remains are most abun-
dant; and I shall here limit myself to quoting the brief but graphic definition of
it which Dr. Buckland has given in his interesting and instructive ‘ Bridgewater
Treatise : —“To the head of a Lizard it united the teeth of a Crocodile ; a neck of
enormous length, resembling the body of a Serpent; a trunk and tail having the
proportions of an ordinary quadruped; the ribs of a Chameleon ; and the paddles of a
Whale. Such are the strange combinations of form and structure in the Plesiosaurus,”
(p. 102.) I may add, that of all existing Reptiles the Chelonians make the nearest
approach to the present remarkable extinct genus in the length and flexibility of the
neck, in the size of the true body of the atlas, which resumes its narmal relations
with the neural arch of that vertebra in Chelys and Chelodina, as in Plesiosaurus ;

60 FOSSIL REPTILIA OF THE

in the natatory form of the extremities as exemplified in the paddles of the Turtle,
which besides being four in number, come much nearer those of the Plesiosaurus in
structure than the paddles of the Whale do, and in the great expanse of the ischium
and pubis: whilst the Plesiosaurs exhibit, next to the Turtles, the greatest deve-
lopment of the abdominal ribs (heemapophyses and their spines), which form a kind
of interwoven flexible ‘‘ plastron” beneath the abdomen.

PLESIOSAURUS BERNARDI, Owen. Tab. XVIII.

Dixon’s ‘Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex,’ p. 396.

In my ‘ Report on British Fossil Reptiles,’ one species of Plesiosaurus, viz. Plesio-
saurus pachyomus. was defined from remains discovered in the green-sand division of the
Cretaceous series;* and the existence of the genus Plestosaurus, at the period of the
deposition of the latest member of that series, was inferred from the discovery of the
femur of a large species in the chalk which forms the well-known “ Shakespeare’s
Cliff’ near Dover.}

This indication has been since confirmed by the discovery not only of the teeth
above described, but of vertebrze of the Plesiosaurus in the same formation; and the
cervical vertebra figured in T. XVIII, which was obtained from the Upper Chalk at
Houghton, near Arundel, Sussex, indicates a species allied to the Plesiosaurus
pachyomus from the green-sand of Cambridge.

The following are the dimensions of the vertebra from Houghton, and of the most
perfect of those of the above-cited species from the green-sand.

Pl. pachyomus. Pl. Bernardi.
Inches. Lines. Inches. Lines.
2 0 1 9
9 3 0
6 2 0

Antero-posterior diameter of centrum
Transverse diameter

b pt

Vertical diameter

The breadth of the centrum is proportionally greater in the vertebra from the
chalk, which further differs from that from the green-sand in the lower position, and
the anchylosis of the pleurapophyses, pi (hatchet-bones or cervical ribs) ; which, if they
presented the characteristic expansion of their extremities, must have supported the
hatched-shaped head on an unusually long body or pedicle. The articular surfaces of
the centrum are more concave than in most Plesiosauri, and deepen to a central pit,
in which they resemble those of the Plesiosaurus pachyomus ; but the circumference of
the articular surface is more extensively rounded or bevelled off, so that its convexity
is Seen, as at ca, ep, upona side view of the vertebra, fig. 3, Tab. XVIII.

* Report on British Fossil Reptiles, Trans. Brit. Association (1839), p. 74.
+ Ibid., p. 193. This specimen was kindly transmitted to me by J. Wickham Flower, Esq.

CRETACEOUS FORMATIONS. 61

Both neurapophyses, fig. 3 (x), and pleurapophyses (p/) are anchylosed to the
centrum. The neurapophyses coalesce together, and send almost vertically upwards a
spinous process, which exceeds in length the whole vertical diameter of the vertebra
below it, and is more than twice its own antero-posterior diameter; it is compressed
and gradually decreases in thickness as it rises; it presents a rough shallow tract along
its fore part (fig. 1), and a wider, deeper, and smoother excavation behind (fig. 2)-
Two small zygapophyses are developed from both the fore-part (-) and back part
(z!) of the neural arch. The pleurapophyses (p/) are long, sub-depressed, slightly
expanded as they extend downward, outwards, and backwards ; but the fractured ends
do not show how far they have extended forwards and backwards into a hatchet-
shaped extremity. They have coalesced with the lower part of the sides of the
centrum, an extent more than their own vertical diameter intervening between them
and the base of the anchylosed neurapophyses. The articulated cervical ribs in the
Pl. pachyomus have not quite so low a position on the centrum, and are thicker
vertically.

The under part of the centrum presents two deep pits from which the vascular
canals ascend, divided by a moderately thick, convex, longitudinal bar (fig. 4). The
non-articular surface of the centrum is smooth, and the sides of the centrum are
slightly concave.

A very interesting and well-marked species of the singular genus Plesiosaurus, in
addition to those from the older secondary strata, is thus indicated by the present
unusually perfect fossil vertebra. As it was discovered on one of the estates of his
Grace the Duke of Norfolk, I avail myself of the opportunity of fulfilling a wish of my
lamented friend Mr. Dixon, and of gratifying my own, by dedicating this new species
to the memory of Lorp BERNARD HowarbD, a young nobleman of great promise and
most amiable disposition, and who had given much attention to the science of geology :
he died suddenly in Egypt at the early age of twenty-one years, whilst pursuing his
travels in order to acquire a knowledge of the antiquities, the arts, and policy of
distant countries.

PLESIOSAURUS CONSTRICTUS, Owen. ‘ab. IX, figs. 6 and 7.

Dixon’s ‘ Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex,’ p. 398.

The species of Plescosaurus from the Chalk-pit at Steyning, Sussex, indicated by
the centrum of a middle cervical vertebra, which is figured in T. IX, figs. 6 and 7,
differs from that of the Plesiosaurus Bernardi, (TY. XVIII,) in its great length, as compared
with the height and breadth of the articular surfaces of the centrum, and in the small
size of the costal articulation (pi), the pleurapophyses having been unanchylosed to the
centrum ; it also differs from all the species of Plesiosaur hitherto defined in the degree

62 FOSSIL REPTILIA OF THE

of lateral constriction of the centrum between those surfaces, if this be natural. The
free or non-articular surface of the centrum is rugose, showing the coarsely fibrous
texture of the bone. The under surface (fig. 6) is slightly concave, both transversely
and longitudinally, is subquadrate and oblong, with two approximated vascular orifices
at its centre, separated by a slight rising, which is not developed into a ridge. The small
costal surfaces (p/) are elliptic, situated at the middle of the ridge dividing the under
from the lateral surfaces of the centrum, twice their own vertical diameter below the
neurapophysial surfaces, and equidistant from the two ends of the centrum. The
articular surfaces here are convex at their circumference, slightly concave in the rest
of their extent, with a feeble longitudinal rising at the centre, interrupted by a trans-
verse linear groove. The neurapophyses terminated below in a very open angle. The
vertebra appears to have been subject to pressure, and is slightly distorted; but it is
difficult to conceive how this could have operated so partially as to have produced
the compressed character of the middle of the centrum and have left the two articular
ends of their natural form.
The following are its principal dimensions.

Inches. Lines.

Antero-posterior diameter of centrum. . : : 2 4
Transverse diameter of articular surface of ditto 2 2
Vertical diameter of ditto 1 74
Distance between the neurapophysial aaa rata it 1 0
Transverse diameter of middle of centrum above the costal

pits . . : : : . : é : : 1 7

It is most probable that the teeth of the Pleszosaurus, T. IX, figs. 8 and 9, belong,
by reason of their size, to the Plesiosaurus Bernardi.

A much-fractured tooth, (Tab. IX, fig. 10,) as thick as those of figs. 9 and 18, but
diminishing more rapidly to the apex, shows similar unequal but more numerous
ridges all round the enamelled surface; its crown is composed of the same kind of
hard dentine as in the Crocodiles and Plesiosaurs, with a moderately thick covering
of enamel. The tooth may be a variety of the Plesiosaurian type, or it may have
belonged to a Steneosauroid Crocodilian. It was obtained from the same chalk-pit, at
Houghton, near Arundel, as the vertebra of the Plesiosaurus Bernard.

The teeth, figs. 7 and 8, T. XX, present more slender proportions, and so far, are
more strictly Plesiosauroid. The fang is round, smooth, and deeply excavated by the
pulp-cavity, which is indicated by the dotted line at »; the enamelled crown supports
numerous fine longitudinal ridges: it is rather more compressed at its fractured end
than in the typical Plesiosaurian teeth. These specimens were found in the lowest
bed of the Lower Green-sand beneath Shanklin Chine, Isle of Wight; I am indebted
for the drawings of them to John Edward Lee, Esq-, of the Priory, Caerleon, Mon-
mouthshire.

CRETACEOUS FORMATIONS. 63

VERTEBRA OF A PLESIOSAURUS.

The subject of T. XIX is a mutilated vertebra, there figured of the natural size,
which was obtained from the Chalk-pit at Burham, in Kent, and is now in the
Collection of Mrs. Smith, of Tunbridge Wells.

The centrum, slightly concave at both ends, with a large vertically oval depression,
fig. 3, pl, for a rib on each side, and with a pair of vascular foramina on its under
surface, fig. 2, ¢,c, shows the characters of the genus Plesiosaurus, with which the
structure of the neural arch is conformable.

The following are the chief dimensions of this vertebra.

Inches. Lines.

Antero-posterior diameter of the centrum 5 A é fi 2 2
Transverse diameter of its articular end . 5 z A ; 3 0
Vertical diameter of ditto 3 0

This vertebra differs from that of the Plesiosawrus Bernardi, not only in the
proportions indicated by the dimensions above given, but likewise by the non-
anchylosis of the rib, and by the shape and position of the surface for its attachment
to the centrum: and if the value of these differences were to be questioned on
the ground that the present vertebra might be one nearer the back than the vertebra
figured in T. XVIII, at which part of the spine the cervical ribs increase in size, have
their junction raised nearer to the neural arch, and retain longer their individuality in
the species in which they become anchylosed in the more advanced vertebre, there
would still remain the following differences:—the vascular foramina on the under
surface are not situated in such deep and well-defined pits; the concave terminal
articular surfaces have not the central depression: the sides of the centrum are not
bevelled off at the border of these articular surfaces, but are divided from them at a
right angle by a well-defined margin. My present experience of the constancy of such
secondary characters in the cervical vertebrae of the same species of Plesiosaurus, leads
me to conclude that the vertebra figured in T. XIX is of a distinct species of Pleszo-
saurus from that figured in T. XVIII, a conclusion to which we are also led by the
consideration that the vertebral bodies usually gain in breadth as they approach the
back, whilst the vertebra, (T. XVIII.) with a lower placed rib, is relatively broader than
the present one. From the Plesiosaurus pachyomus, from the Green-sand of Reach,
near Cambridge,* the present specimen differs in the form of its costal surface, which
is vertically instead of being transversely elliptical: it is still more obviously distinct

* Report on British Fossil Reptiles, 1839, p. 74.

64. FOSSIL REPTILIA OF THE

from the Plestosawrus constrictus, from the Chalk of Steyning, in Sussex. Although
the sutures connecting the neural arch with the centrum are traceable, there has been
a certain degree of anchylosis, which has helped to maintain the arch in its natural
connection, notwithstanding the degree of pressure and distortion to which the whole
vertebra has been subject. Each neurapophysis, which measures one inch five lines
in antero-posterior diameter at its narrowest part, is smoothly rounded off at both its
free borders, of which the anterior one is the thickest; the posterior zygapophysis is
developed at rather more than an inch above the base of the neurapophysis; its flat
oval articular surface looks downwards, and a little outwards: the neural canal is
relatively wider than in the Plesiosaurus Bernardi, and its area is oval, with the great
end downwards. The spinous process, of which nearly four inches is preserved, has
an antero-posterior diameter at its base, of nearly two inches, and is strengthened
behind by two buttress-like ridges, which rise converging from the summit of each
posterior zygapophysis: bounding an angular depression at the back part of the spine,
as in the Plesiosaurus Bernardi, and many other species. The total height of this
vertebra, as far as the spine is preserved, is seven inches and a half, and the total
length of the Plesiosaurus, to which it belonged, was probably not less than sixteen
feet. There are preserved in the same block of Chalk with the vertebra above
described, the summit of the neural arch, with the base of the spine of another
vertebra, and a portion of one of the long ribs of the thorax, fig. 1, pi.

PLESIOSAURUS PACHYOMUS, Owen. T. XX, XXI.°

‘Report on British Fossil Reptiles,’ Trans. Brit. Association, 1839.

This species of Plesiosawrus was founded on certain remains discovered in the
Upper Green-sand at Reach, about six miles from Cambridge, and placed by the
Rev. Professor Sedgwick in the Wordwardian Museum of that University.

The specific name “ pachyomus’* relates to the unusual thickness of the humerus,
the distal flattened end of which is one inch and a half thick, the breadth of the
same part being only four inches and a half, and the length of the entire bone nine
inches and a half. ‘The contour of the articular head is transversely oval. The
central part of the bone is occupied by a coarse cellular structure, one inch and a
half in diameter, surrounded by dense osseous walls, three lines thick.

In the rich and instructive collection of Reptilian fossils, from the Cretaceous
deposits in Cambridgeshire, in the possession of James Carter, Esq., M.R.C.S., of
Cambridge, there are several vertebral bodies or “centrums” of the same species o
Plesiosaurus which show the change of proportion in the breadth and depth of the

* Tlayus, thick, duos, humerus, or arm-bone.

CRETACEOUS FORMATIONS. 65

centrum which the vertebree undergo as they pass from the region of the neck to that
of the back, without corresponding alteration in the length of the centrum.
The following are dimensions of the most perfect specimens of these vertebre :

Anterior Middle Posterior Last

Cervical. Cervical. Cervical. Cervical.

In. Lines.| In. Lines.) In. Lines.) In. Lines
Antero-posterior diameter, or length : . Alauidh 9 2 0 2 0 1 Fi)
Transverse diameter, or breadth 6 5 A Al 24 3 2 3 2 9 3 0
Vertical diameter, or height . , ‘ ; alee! 9 2 3 | 2 6 2 7
Breadth of neural surface (middle) . 4 : : —_— 0 23) 0 5 0 6
Breadth of neurapophysial pit 9 : : : — 1 1 1 3 1 9
Breadth of costal surface . r . ‘A 4 : — 1 0 1 03 —
Height of ditto . : : : : c : — 0 10 1 0 —
Distance between neurapophysial and costal pits pea! 0 0 9 0 73 —

The above dimensions show that whilst the centrums retain the length of two
inches in the middle and towards the posterior parts of the long neck, they become
shortened in the penultimate and last cervicals to the length of the smaller vertebra
towards the anterior part of the neck; the difference, however, is but slight, and
whilst an almost uniform length is retained, the vertebral centrums augment in height,
and still more in breadth, as they approach the region of the back.

With the increased breadth of the centrum, there is a concomitant increase in tha
of the rough depressions (T. XXI, figs. 3 and 4, np) for the articulation of the neur-
apophyses, and, at the same time, the bases of these vertebral elements become wider
apart, and the breadth of the surface (ib. nn) supporting the neural axis, increases.
This smooth surface which occupies the middle of the upper part of the centrum is
contracted in the middle by the approximated neurapophysial pits, where there is on
each side the orifice of the canal for the vertebral vein or sinus which traverses the
centrum vertically. The lower openings of these canals are shown in T. XXI, figures
2 and 5, and their whole course is displayed in the fractured vertebra rrepresented in
fig. 6, ec’.

The costal pits in the greater proportion of the cervical vertebree present the form of
a full transverse ellipse, asin T. XX, fig. 1, and are situated below the neurapophysial pit
at a distance about equal to their own vertical diameter. They are nearer the posterior
than the anterior surface of the vertebra, and thus differ in position as in shape from
the costal surface in T. XIX, fig. 3, pt. As the cervicals approach the dorsal region
the costal pit increases in vertical extent, assumes a circular form, and, as in all

Plesiosauri, begins to rise towards the neurapophyses. The commencement of this
9

66 FOSSIL REPTILIA OF THE

change in form and position of the costal pit, pi, is shown in T. XX, fig. 3, and its
borders are here seen to be rather prominent. In none of the vertebrz has the costal
pit presented the groove which, in most Plesiosauri, crosses it in the axis of the vertebra
and divides it into two subequal parts. The articular ends of the centrum are slightly
concave and are impressed by a circular pit at the centre; the peripheral margin is
rounded off; it appears in the side view of the vertebra, fig. 3, T. XX, but not to
such an extent as in Plestosaurus Bernardi, T. XVIII, fig. 2. The lower apertures of
the venous canals are closely approximated in all the cervicals except the most pos-
terior ones, in which the canals diverge, as they descend, with a proportionate breadth
between their lower outlets, c' ¢’, fig.2,T. XXI. They are divided by a narrow ridge,
as in fig. 5, in the ordinary cervical vertebree, and are not situated in fossz, as in the
Plesiosaurus Bernardi, T. XVIII, fig. 4.

In the vertebra which I take to be the penultimate or antipenultimate cervical, the
upper half of the costal surface has passed upon the base of the neurapophysis, and,
from what remains upon the centrum, as at pi, fig. 5, T. XX, we may see that the
surface has undergone a further change of form, and has exchanged the circular (as
in fig. 3) for a vertically elliptical or oval figure.

In the centrum of the last cervical vertebra figured in T. XXI, figs. 1, 2, 3, the
last trace of the costal surface is shown at pi, fig. 1. And I may here remark, that, as
there is no definite natural distinction between the cervical and dorsal regions of the
Plesiosaurus, the vertebrze in both supporting ribs, and the transition in the size,
shape, and position of these being more gradual than in the Crocodiles, I have selected
the arbitrary character of the impression of the costal articular surface, or any part of
it, upon the centrum, as the character of the cervical vertebre in the Pleszosaurus, and
I count that to be the first dorsal in which the costal surface has wholly ascended upon
the neurapophysis.

In T. XXI, fig. 7, one of the caudal vertebre is figured showing the longitudinal
channel, at the middle of the under surface, bounded by the ridges which terminate on
the articular surfaces for the hamapophyses: those surfaces are here worn away. The
neurapophyses have coalesced with the centrum; and the ribs have also coalesced,
forming the ‘transverse processes’ of this caudal vertebra.

PLESIOSAUROID PADDLE. ‘Table XVII.

The block of Chalk from the pit at Burham, in Kent, figured in Tab. XVII,
includes parts of four digits of the same foot, the phalanges of which had the opposed
ends flattened, and joined together vy ligament, the whole forming part of the bony
framework of a large fin, most resembling that of the Plesiosaurus. This fine specimen
forms part of the rich Collection of Chalk-fossils belonging to Mrs. Smith, of Tonbridge

CRETACEOUS FORMATIONS. 67

Wells. Had Cuvier’s conjecture, that the extremities of the M/osasaurus resembled
those of the Plesosaurus, been supported by the evidence of such remains of extremities
referable to A/osasawrus as have been discovered since his time, the present remarkable
specimen from the Chalk Formations of Kent, might have been ascribed with some
degree of probability to the great Lacertian of the Maestricht Chalk. But the evidence
which has been adduced from the remains of extremities of the Mosasaurus from the
Green-sand of New Jersey, in the United States,* is incompatible with the supposition
that the phalanges of the J/osasaurus were united by.flattened surfaces and syndosmosis.
No remains of the Mosasaurus, so far as I know, have been discovered in the Chalk-
pit at Burham, but some vertebrae of Plestosaurus have been obtained from thence,
including the fine one figured in T. XIX. Jn the specimen figured in T. XVII,
fig. 1, three phalangeal bones, and part of a fourth are preserved in one digit, three
phalanges in the adjoining digit, and one phalanx of the next, which, if it be in its
natural relative position, would belong either to the outermost or the innermost digit;
and this is the more likely, as the phalanx of a fourth digit is on the same parallel
with the proximal phalanges of the two best preserved digits. In the paddle of the
Plesiosaurus the phalanges of the three middle digits are on the same transverse
parallel, whilst those of the outer and the inner digits are on a higher or more
‘ proximal’ plane.

of a pentadactyle paddle, and that the phalanx marked » has belonged to either the
inner or the outer terminal digit. If the fragment of bone that closely adheres by a
flat surface to the proximal end of the phalanx #, belong to the small carpal bone
which articulates with the second digit in the paddle of the Plesiosaurus, we must
consider the phalanx to which it is attached, and the two parallel phalanges, as
appertaining to the proximal series: but that fragment may be a remnant of a
proximal phalanx itself. The proximal surface of the three phalanges is slightly
concave: the shaft of the phalanx is thick and strong; rather compressed from before
backwards; gradually contracting to the middle part. Their substance presents a
coarse cancellous texture throughout, with the cells or intervals widest at the middle
of the bone. The parts being represented of the natural size, it is unnecessary to
specify the dimensions of the phalanges. If the length of the proximal phalanx be
taken with the compasses in digits i and iv, it will be found that the two following
phalanges progressively decrease in length. On the supposition that the phalanges of
these digits are the first, second, and third, we may estimate the length of the entire
paddle, according to the proportions of that of the Plesiosaurus Hawkinsii, at sixteen
inches; which would accord with the proportions of the vertebra of the Plesiosaurus
from the same pit, figured in T. XTX.

* Quarterly Journal of the Geological Society, Jan., 1849, See also, ante, pp. 37—39.

68 FOSSIL REPTILIA OF THE

In the instructive Collection of Tomas CHARLES, Esq., of Maidstone, is part of a
single digit of the paddle, T. XVII. fig. 2, of apparently the same species of Plesio-
saurus. It includes three phalanges, and part of a displaced small phalanx of an
adjoining digit. In comparison with the more perfect paddle in Mrs. Smith’s collec-
tion, I regard the phalanges in the present specimen as being the third, fourth, and
fifth of their digit.

Genus, ICHTHYOSAURUS.

If the investigation of the fossil remains of the Chalk-beds had been undertaken
by the Comparative Anatomist, without previous knowledge of the fossils of the lower
secondary formations, he would have perceived in the teeth which form the subjects
of T. XXIV, characters not only specifically, but generically, distinct from any of the
teeth that have been previously described and figured in the present monograph. The
thick conical crown covered by enamel, raised into numerous longitudinal ridges, would
have offered, it is true, a repetition of the general character of that of the teeth of Polypty-
chodon ; but the continued expansion of the base or fang of the tooth, and the coarser
longitudinal ridges and grooves with which most of the surface of that part is sculp-
tured, would be a peculiarity distinguishing the present from any of the previously
noted teeth from the Cretaceous or Tertiary series, and still more so from the teeth of
any known existing Reptile. It is only, indeed, those of the largest Crocodiles or
Alligators that can compete with the present fossil teeth from the Chalk-formations in
point of size; and the crowns of these, as in the teeth of the Polyptychodon, differ from
the teeth of the Crocodilia in the absence of the two opposite ridges, forming or indi-
cating the edges of the crown; whilst their base also differs from that of the
Crocodile’s tooth in the structure above defined,—a difference which becomes more
manifest when a section of that part is made, demonstrating that the expanse of the
fang is due to the unusual thickness of the osseous external crust called ‘ cement.’
The Anatomist, I say, would be justified in deducing from these characters the generic
distinction of the Reptile to which they had belonged, but he could have formed no
suspicion of the truly extraordinary modifications of the entire reptilian organisation that
had been associated with such generic modifications of the teeth. Such fossil teeth,
having a conical, enameled, and commonly striated crown, offermg a considerable
range of variation in its proportions, and supported by an expanded, usually solid, and
coarsely-grooved fang, covered by a thick coat of cement, have been recognised, since
the publication of Sir Everard Home’s Paper ‘ On the Remains of an Animal linking the
class of Fishes to that of the Crocodile,’ published in the Philosophical Transactions
for 1814, as belonging to that genus of animal to which Home gave the name of
Proteosaurus, but to which Naturalists have concurred in applying the more classically

CRETACEOUS FORMATIONS. 69

constructed and appropriate name of Jchthyosaurus, suggested for it by the estimable
and accomplished keeper of the Mineralogical Department of the British Museum,
CHARLES Konie, K.H., F.R.S.

Remains of species of Jchthyosaurus are found in secondary strata from the Chalk
down to the Muschelkalk, and most abundantly in the Oolite and Lias. In my
‘Report on the British Fossil Reptiles,’ I recorded the discovery of “ portions of the
lower jaw with teeth of a large species of Jchthyosaurus from the lower Chalk between
Folkstone and Dover, which was closely allied to the Jchthyosaurus communis. And in
the description of the Fossil Reptilia in Mr. Dixon’s work ‘ On the Geology of Sussex,
some teeth from the Chalk of Kent, now preserved in the Museum of William
Harris, Esq., F.G.S., are figured in T. XXXIX, fig. 10, where they are stated to
belong to the genus Jchthyosaurus, and to correspond so closely in form and size with
those of the Jchthyosaurus communis, that I did not presume, in the absence of any
knowledge of the skeleton, to pronounce them to belong to a distinct species.

I have since been favoured with the opportunity of studying and comparing the
required parts for yielding more satisfactory characters, and have arrived at a convic-
tion of the distinction of the species of Ichthyosaur of the Chalk-epoch from that of
the Lias, which it most resembles in the general shape and proportions of the teeth,
a distinction first recognised by James Carter, Esq., M.R.C.S., of Cambridge, who
proposed for the species the name of Jchthyosaurus campylodon, at the ‘ Meeting of
the British Association’ at that University in 1846, on the occasion of the exhibition
of some fine remains of the species obtained by him from the Lower Chalk, in the
vicinity of Cambridge, in 1845. Before describing these remains, I shall give an
account of the additional specimens from the locality whence I derived the first evidence
of the presence of remains of the Zchthyosaurus in the Cretaceous strata.

ICHTHYOSAURUS CAMPYLODON, Carter. Lower jaw, Tab. XXIII.

In the operations upon the Chalk-cliffs connected with the Dover Railway, a
considerable proportion of the lower jaws and fragments of the ribs of a large Jchthyo-
saurus were brought to light; they were dislodged from the hard gray chalk at the
end of the Round Down Tunnel, about two miles and a half from Dover, under the cliff,
four feet from the beach beyond “ Shakespeare’s Cliff,” towards Folkestone.

The specimens are now in the collection of H. W. Taylor, Esq., of Brunswick Place,
Brixton Hill, to whose kindness I am indebted for the present opportunity of describing
and figuring them.

The principal portion consists of four coadaptable fragments of the left ramus of
the lower jaw, including nearly the whole of the dentary piece, and fragments of the
splenial and angular pieces, the whole measuring two feet seven inches in length, but

70 FOSSIL REPTILIA OF THE

without the natural anterior termination; and wanting all that extensive hinder part
of the ramus formed by the angular and surangular pieces. The inner alveolar plate
of the dentary is broken away; but the vertical diameter of the outer part of the bone,
from being 2 inches 6 lines at the hinder end, gradually decreases to 1 inch 9 lines at
the fore part. A few teeth have been cemented to the alveolar plate in the anterior
fragments, and perhaps in the places near which they were found, for numerous
scattered teeth of the Zchthyosaurus campylodon, and doubtless of the same individual as
the jaws, were exposed in the fragments of the Chalk rock containing those parts.

The outer surface of the dentary bone, T. XXIII, fig. 1, is convex, the inner surface
at the part where the second joins the third fragment, about 1 foot 6 inches from the
anterior end, is divided into two longitudinal channels by the base of the inner alveolar
wall; which base is perforated lengthwise by the dental canal. As we trace this part of
the dentary backwards, the alveolar groove progressively shallows and diminishes, and
the lower groove widens and increases; the section of the dentary at the back part of
this fragment, two feet from the fore end of the whole portion of the bone preserved,
presenting a sort of hour-glass form, the upper and under portion being connected by
a very thin plate. The form of the section displayed at the fractured end is given in
T. XXIII, fig. 1*. The coarser central osseous texture appears to have been included
within a thin, dense, exterior crust, about a line in thickness, and the same crust
surrounds the canal ¢. The outer surface of the dentary piece shows a shallow groove
about two thirds of an inch below the outer alveolar border, into which groove the
several vascular foramina open which are continued from the canal, fig. 1 ¢.

The portion of the right ramus of the same lower jaw, T. XXIII, fig. 2, includes
the termination of the splenial pieces, and the commencement of the symphysis
and includes an extent of the dentary piece, 32, measuring one foot three inches in
length. The vertical diameter of the dentary at the hinder fractured end, fig. 2%, is
three inches, and at the front end, fig. 2**, is two inches two lines. The inner alveolar
plate is sent off about an inch below the upper border of the thick outer plate; and
forms the floor of the groove before it rises to form the inner wall; it slightly increases
in thickness in forming the rounded border of that wall; the diameter of the floor of
the socket is three lines. The depth of the socket is two inches three lines, its breadth
is ten lines and a half. Portions of both splenial bones, somewhat dislocated, are
shown at 31, 31.

The cavity in the dentary beneath the alveolar wall is reduced to a mere groove
midway between the fractured ends, with the exception of which the whole of the now
flattened inner surface of the dentary is in contact with its fellow, forming the strong
and long symphysis menti. At the fore part of the fragment the. alveolar groove is
reduced to a depth of eleven lines, and a breadth at its outlet of nine lines. One of
the transverse canals is exposed at the anterior fracture, which passes from the inner
longitudinal canal to the outer groove. Wherever the bone is broken, that modification

CRETACEOUS FORMATIONS. i

of its outer surface is shown, which gives it the appearance of forming a crust about a
line in thickness, of a different texture from the rest of the bone.

The fragment, T. XXIII, fig. 3, is a portion of the right premandibular bone,
showing a cast of the dental vasculo-nervous canal, and the outlets terminating at the
orifices on the outer side of the bone.

The teeth, supposing them to have been correctly restored, decrease in size, as in
the [chthyosaurus communis, near the anterior end of the dentary piece.

The largest tooth in this portion of the jaw, placed one foot from the anterior end,
has a crown eleven lines in length, straight, conical, rather obtusely pointed, five lines
and a half in diameter, with numerous, not very sharp, but close-set ridges, narrowing
as they approach the summit, and subsiding before they attain it. The cement-
covered base continues to expand as it descends, with a smooth exterior for about one
third of its extent from the crown, and with coarse longitudinal striations or wrinkles
over the rest of its extent. The surface of the base in most of the teeth, like the
surface of the bone, is coated by a firm crust, sparkling with minute crystals of pyrites.
In the attempt to remove this coating, the parts have been more or less injured, so
that the precise character of the external markings, and original shape of the thickened
fang, cannot be ascertained. The transverse section of the crown of the tooth is
circular at its apical half, but widens into a full ellipse towards the base; that of the
smooth beginning of the base is a modified ellipse, which in the rougher and more
expanded part of the base, seems to take on a subquadrate form.

The teeth differ in size at different parts of the jaw; in the first or foremost of the
series the crown of the tooth is only four lines in length in the lower jaw, and it
gradually increases to eight and ten lines in length,—the total length of the longest tooth
being two inches and a half. Some of the scattered teeth adherent to the present
fragments having very short and thick crowns. In fig. 4, the crown is as wide at
its base as it is long: a portion of the thick cement has been removed from the fang
just below the crown, and exposes the grooved exterior surface of the dentinal base
of that part of the tooth.

In the Lchthyosaurus communis, the teeth of which most resemble those of the present
species from the chalk, the crown of the tooth tapers more gradually to the apex;
and the enamel ridges are immediately continued upon broader rounded ridges of the
cement-covered fang, which become more strongly marked as the fang recedes from
the crown, and are divided by deep grooves, giving a fluted character to the base of
the tooth, which is proportionally less expanded, and retains more of the circular form
in transverse section. (See T. IV, fig. 17.)

In the few more or less imperfect teeth of the Jchthyosaurus from the chalk, which
I had seen whilst drawing up, in 1838, my Report on ‘British Fossil Reptiles,’ the
differences above specified were not manifested so clearly as in the more numerous
and complete examples which have since been submitted to me. The smooth exterior

72 FOSSIL REPTILIA OF THE

of that part of the fang next the crown, in the Jchthyosaurus campylodon, is due to a
thick coat of cement; the dentine so covered shows a fluted character, only differing
from that of the teeth of the Jchthyosaurus communis in bemg more regular and some-
what finer. This is shown in T. XXIII, fig. 4.

Not any of the detached teeth discovered with the above-described portions of jaw
present any well-marked curvature of the base. The characteristics of the teeth of
the Ichthyosaurus campylodon are best displayed in those specimens that have been
obtained from the cretaceous deposits in Cambridgeshire.

TEETH OF ICHTHYOSAURUS CAMPYLODON. Tab. XXIV.

The detached teeth from the Cambridge Chalk and Green-sand present two
modifications of form: the majority are straight, the rest curved, chiefly owing to a
slight inward bending of the thickened fang. These latter have been proved to come
from the lower jaw, and the curvature relates, as Mr. Carter has well remarked, to
the more oblique direction outwards of the alveolar groove in that jaw, which is
compensated by the curvature of the teeth, the crowns of which are thereby brought
into more direct apposition with the teeth above.*

The enameled crown in all the teeth (figs. 1, 2, 6 c) is a cone, short and thick in the
largest teeth, with a circular or very full elliptical transverse section; it is a longer and
narrower cone in most of the smaller teeth. The ridges of the enamel are numerous
and fine, not always of equal thickness; the intervening grooves are rather narrower
than the ridges. In some teeth, shorter and narrower ridges are seen in the basal
intervals of the longer ridges: in other teeth the ridges are thicker at the base of the
crown, and are occasionally impressed or divided there by a shorter longitudinal
groove. All the ridges subside before they reach the apex of the crown, which is
smooth. The enamel terminates at the base of the crown by a thin well-defined
border. The tooth continues to expand beyond this border, and, for an extent
varying from one third to one fifth of the entire fang. The surface is smooth; not
any of the longitudinal furrows or ridges of the enameled crown being continued upon
that part of the cement-covered fang. Ina few teeth, the base of the crown is well
defined, as Mr. Carter has remarked, by an annular projection, T. XXIV, figs. 3 and 4,
The rest of the base or fang of the tooth, beyond the smooth part, presents coarse
longitudinal ridges and grooves, is much expanded in most of the teeth, and in many
it presents, as in the tooth figured and described by Mr. Carter,t a square shape.
This character is best marked in the straight teeth from the upper jaw; it arises out
of the progressive growth of the osseous cement of the fang, which seems to have

* London Geological Journal, vol. i, p. 9.
+ Loe. cit., p. 8, figs. @ and 4.

CRETACEOUS FORMATIONS. 78

been only checked by the resistance of the alveolar walls on the outer and inner sides
of the tooth, and by the contiguous teeth before and behind. Thus, by this thickening
of the fang, the teeth must have become wedged together in the common alveolar
groove, and the absence of partitions completing the sockets must have been in some
measure compensated by this firm impaction. This is shown in the part of the fractured
jaws. (Tab. XXVI, fig. 2.)

Figs. 3 and 4, T. IV, give two views of a portion of the alveolar groove with
one tooth thus squarely wedged in its place, part of the adjoining tooth on one side,
and part of the socket on the other, in which a thin bony partition had been formed
for a short extent of the base of the tooth. The extent of the square root in the
direction of the long axis of the jaw, fig. 4, is commonly greater than the transverse
diameter of the same root, fig. 3. The tooth is never wholly consolidated even in this
fully developed state of the fang: a remnant of the uncalcified pulp has always been
retained in the central dentinal part of the enlarged fang, after the crown has been
completed. This is shown in the: fractured specimen, fig. 5, in which the square fang
beyond the cavity, 0, is one solid mass of coarse cement; and more clearly in the
transverse section, fig. 6,in which c is the cement, d the dentine, and a the pulp-cavity.
The view given at fig. 6’ shows the consolidated base of the thickened fang,—a
character by which the teeth of the Ichthyosaurs differ from those of almost all other
Saurians, and especially from the Crocodiles, in which the base of the tooth always
remains widely open.

Notwithstanding, however, the resistance which must be opposed by the thickened
and consolidated root of the tooth of the Ichthyosaur, it is affected by the germ of the
succeeding tooth in the same way as in the Crocodilia. J have seldom, indeed, seen
the process better illustrated than in a series of the teeth of the [chthyosaurus cam-
pylodon in Mr. Carter’s collection, obtained from the Chalk in the neighbourhood of
Cambridge.

Fig. 7 is a tooth with a thick, straight, square fang ; probably, therefore, from the
upper jaw, which shows on one of the broader sides of the base a shallow elliptical
depression, o. ‘This is caused by the progressive absorption excited by the pressure
of the soft matrix of the successional tooth which was in the course of development at
the angle of the alveolar groove on the inner side of the base of the tooth in place.
In the Ichthyosaur’s tooth the absorption causes a simple excavation in the substance
of the thick cement ; but in the Crocodile’s the same process speedily penetrates the
thinner wall of the large cavity in the base of the tooth, as is shown in the figure of
that of an Alligator (fig. 11), where a circular aperture is the result of the pressure. As
the new tooth of the Ichthyosaur grows, the thick cement of the old tooth yields,
and the reduced pulp-cayity in the centre of the fang is penetrated, as is shown at
fig. 8, o, where the absorbent process has extended nearly across the whole solid base of
the fang, fig. 8’. In fig. 9 the germ of the tooth is preserved, which has penetrated

10

1a FOSSIL REPTILIA OF THE

the breach so excavated ; and as both this and the preceding tooth (fig. 8) are from the
lower jaw, the direction in which the fang is bent demonstrates that the germs of the
new teeth were developed from the inner angle of the bottom of the alveolar groove,
and affected the inner side of the base of the fully formed teeth, as in the Crocodiles.
In fig. 10 the crown and the smooth beginning of the fang of the successional tooth
have been completed, and it is seen enclosed by part of the debris of the old tooth
which it is about to replace. As in all young teeth, the crown is a thin shell of the
first-formed layers of dentine, with a thin coat of enamel, the ridges of which seem
not to have been quite completed.

The teeth of the Ichthyosaurus are smaller at the two extremes than at the middle
of the series in both jaws; and some modifications of form are presented in these
teeth, which do not, however, overpass the recognisable limits of the specific characters.

Fig. 13 is a tooth probably from the back part of the series in the upper jaw, in
which the crown is less broad at its base and relatively longer than in the large
teeth from the middle of the series; the rough expanded fang presents in transverse
section a long ellipse, with its angles truncated, making but a slight approach to the
quadrate figure of the fang of most of the larger teeth; but in the fine striation of the
conical enamelled crown, in the smooth tract of unenamelled fang which precedes the
roughly striated expanded portion, and in the degree of expansion of this part, all the
distinctive characters of the Jchthyosaurus campylodon are preserved.

Figure 14 is an incompletely formed tooth from the opposite end of the dental
series, in which the enamelled crown is unusually short and thick; but the smooth
surface of the portion of the fang which has been formed, which continues to expand
to the widely open pulp-cavity, gives the character of the same species as fig. 13.

In fig. 15, from the Upper Green-sand, we have a tooth in a more advanced stage
of formation: the roughened thickened part of the base has begun to be added; but
this is still widely open, as is shown in fig. 15’.

In Figure 16, a greater proportion of the rough expanded fang is completed, and
the basal outlet of the pulp-cavity is beginning to be encroached upon: but in these
young teeth the cement has not increased im such quantity as to be moulded into the
square form that is so characteristic of the old teeth.

JAWS OF THE ICHTHYOSAURUS CAMPYLODON, FROM THE CAMBRIDGE CHALK.
Tables XXV and XXVI.

The portions of the upper and lower jaws discovered with the teeth above
described, and containmg several teeth of the same character 7m stv, are, as their
possessor, Mr. Carter, truly describes, the most characteristic relic of the Ichthyo-
saurian genus hitherto obtained from the Cretaceous Formations.

The portion of the upper jaw includes an extent of two feet of the premaxillary

CRETACEOUS FORMATIONS. 75

bones, including at the back part about three inches of the exposed, and apparently
pointed terminations of the nasal bones (T. XXYV, fig. 2, 15.) These, however,
extend much further forwards than they appear to do externally, their anterior ends
being overlapped by the premaxillaries, 22. The breadth of the premaxillaries at the
fractured hinder end of this specimen is 53 inches, at the distance of one foot from
that fractured end it is 35 inches, and the decrease seems to have been rather more
gradual in advance of this part. The total length of the jaws from the point of union
of the premaxillaries above the nasals, may therefore be estimated at about three feet.

The breadth of each nasal, where they dip beneath the premaxillaries, is one inch
three lines: the upper surface presents a longitudinal furrow midway between the
margins of the bone, into which furrow a longitudinal ridge at the under surface of the
premaxillary fits, thus strengthening the union between the two bones. The nasal
bone forms a parallel ridge, or angular projection, from its own under surface, which
divides the inferior concavity into two parts, the median and broader concavity being
somewhat angular in form. The actual pointed ends of the nasals are visible at a
fractured surface, (T. XXVI, fig. 2, 15,) nine inches in advance of the point where
they are concealed by the median junction of the premaxillaries: their section here
presents the form of a curved lamina of bone, thickest at its median border, and half
an inch in breadth, and this may be traced beneath the fractured portion of the
premaxillary three inches further forwards.

The breadth of the nasal cavity at the back part of the fractured end, (T. XXVI,
fig. 1,) is rather more than two inches: at the anterior fracture, fig. 2, it is reduced to
ten lines.

The median borders of the premaxillaries, (T. X XVI, fig. 1, 22,) before their
junction above the nasals, (ib. 15,) are about one line thick, and the bone increases to
a thickness of three lines, above the part where it sends off, inwards and downwards,
the inner alveolar border, (ib. a/,) which is at a distance of an inch and three fourths
from the upper median border. On the outside, opposite the origin of the inner
alveolar plate, the premaxillary is traversed by a straight longitudinal groove, (T. XXV,
fig. 1, g,) four lines in breadth, which contracts, as it advances forwards. The outer
alveolar plate, (T. XX VI, fig. 1, a,) increases in thickness to six lines, and terminates
below in a convex border. The inner alveolar plate, (ib. a/,) forms the chief part of the
arched roof of the upper dental groove, and has there scarcely a line in thickness; but
as it descends, it rapidly gains a thickness of five lines at its inferior convex border.
There is a slight solution of continuity between the arched and descending portions of
the inner alveolar plate, (ib. a/’,) at the hinder fractured end of the specimen, and the
descending plates might at first sight be taken for the palatine bones: but these, in
other /chthyosauri, are vertical plates, which lie parallel with, and on the inner side of
the descending alveolar plate of the premaxillary, and do not reach so far forwards as
where the nasals are wholly overlapped by the premaxillaries. The inner alveolar

76 FOSSIL REPTILIA OF THE

plate descends eight lines lower than the outer one, and the outlet of the alveolar’
groove has a corresponding oblique aspect downwards, and a little outwards: the
breadth of the groove at the outlet is 1 inch 2 lines: the depth of the groove, to the
inner border, is 1 inch 6 lines: the breadth of the alveolar part of the premaxillary,
including the plates, is 2 inches and a half. At the anterior fractured end of the
left premaxillary, (T. XXVI, fig. 2, 22,) ten inches in advance of the hinder fracture,
the vertical diameter of the bone is 2 inches 10 lines, the breadth of the lower alveolar
part is 1 inch 9 lines, the depth of the alveolar groove is 1 inch 5 lines, the breadth
of its outlet 1 mch 1 line. Here the two premaxillaries are in contact at the upper
borders, which have progressively increased, after overlapping the nasals, to a thickness
of 7 lines, The inner alveolar plate is sent off about half an inch below the upper
border, extending inwards and downwards, and dividing the nasal from the alveolar
groove, then descending, in contact with the same plate of the opposite premaxillary,
for about an inch of vertical extent: the thickness of the plate near its origin is 3 lines,
whence it increases to 7 lines at its lower rounded border, ib. af’. The elliptical area
of a canal, 4 lines in diameter, o, is exposed above the origin of the inner alveolar plate.
The narrow exterior groove, g, sinks 3 lines mto the substance of the bone, and slightly
expands towards its bottom. The outer groove and the inner canal communicate by
transverse anastomosing channels at certain parts.

The whole of the upper surface of the premaxillaries forms a smooth arch of bone,
describing in transverse section a semicircle, and impressed only by the longitudinal
groove each side, for the lodgement of a vessel on and probably also a branch of the
fifth pair of nerves. ;

The portion of the lower jaw consists of the dentary and splenial pieces,* both
dislocated, the former slighly. At the back part of the left ramus, (T. XXVI, fig. 1,)
the lower border of the splenial, (ib. 31,) has been pressed inwards and downwards
from that of the dentary, (ib. 32,) and slightly rotated so as to incline its inner vertical
wall outwards, where it is pushed into the groove or concavity of the dentary, which
it naturally closes, applying itself to the side of the inner alveolar plate of the dentary.
The right splenial, (ib. 31,) has been still more displaced, its lower border being pushed
against the base of the inner alveolar plate of the left ramus.

Both splenials are exposed at the anterior fracture of the rami, (T. XXVLI, fig. 2,)
six inches in advance of the preceding, the right being here, also, above the left, and
removed from its own ramus to contact with the base of the inner alveolar plate of the
left ramus. The vertical diameter of the splenial. which is two inches at the hinder
fractured part, has diminished to little more than one inch at a distance of five inches

* See the Cut, fig. 9, p. 17, of the ‘ Monograph,’ Part ii, Crocodilia and Ophidia, of the London Clay,
in which the different pieces of the complex lower jaw of Reptiles is figured: and where 29 is the
‘articular,” 29 the ‘‘surangular,”’ 30 the “angular,” 31 the “‘splenial,” 31 the “complemental,” 32 the
*‘dentary,” in the Alligator.

CRETACEOUS FORMATIONS. 77

in advance of this. The splenial has the same shape as in other Jchthyosauri, being a
longitudinal plate, with its lower margin bent outwards at a right angle; this margin
forms the lower border of a great extent of the ramus, underlapping the dentary at
the situation of the posterior fracture, which is a little prior to the junction of the two
rami forming the symphysis ; it is withdrawn to the inner side of the dentary at the
anterior fracture. The ascending or vertical plate of the splenial forms the largest
part of the bone, and is much thicker than in the Crocodile with a jaw of the same
depth : its transverse diameter in the present Ichthyosaur is 3 lines.

The dentary is along bone which, at the hinder fractured part, (T. XVI, fig. 1, 32.)
appears as if it were folded lengthwise twice upon itself, forming a sigmoid transverse
section; but the outer part of the bone increases in thickness as it advances forwards,
and the inner alveolar wall presents, at the anterior fracture, more the appearance of an
accessory plate or process sent off from the inner side of the body of the bone. The
vertical diameter of the dentary pieces is 2 inches 3 lines.

The outer part of the dentary at the hinder fracture is 6 lines in thickness, smooth
and convex on its outer side, which is traversed by a longitudinal groove, y, which
also slightly narrows as it advances. The alveolar plate is continued downwards and
inwards at an angle of about 50°, diminishing in thickness as it descends, and again
increasing after it has risen, to form the inner wall of the alveolar groove. The depth
of the groove is 1 inch 5 lines; its width is 1 inch. At the anterior section, 5 inches
in advance, (T. XXVI, fig. 2,) the alveolar groove (ac) has contracted to a diameter of
8 lines, and is 1 inch 2 lines in depth; the inner alveolar wall, (a/,) has increased in
thickness.

The-lower jaw, in the present fine fragment of skull, appears to have been broken
across just anterior to the meeting of the two rami, where they form the symphysis.

What is wanting in the specimen of the Jchthyosaurus campylodon in Myr. Carter’s
collection to give, ex visu, the proportions of the jaws of that species, is, in great part,
supplied by the fragments from Mr. Taylor’s collection, which had been previously
discovered in the Grey Chalk near Dover.

The hinder end of the portion of the left ramus in that specimen, which measures
2 feet 7 inches in length, has been broken away from the part which corresponds with
the front end of the portion of the same bone in Mr. Carter’s specimen, and this end is
nearly 1 foot distant from the hindmost part of the same specimen. We thus gain an
extent of jaw by this addition of nearly 3 feet, and at least 1 foot more would be
required to complete the whole length of the jaw.

Owing to the partial dislocation of the rami, the aspect of the alveolar groove is
more outwards than is natural; but in the proper relative position it is turned more
obliquely outwards than that of the upper jaw, and the roots of the lower teeth, as
Mr. Carter has well remarked, present a curvature which compensates for the obliquity
of this alveolar groove, and gives a more vertical direction to their crowns.

78 FOSSIL REPTILIA OF THE

This characteristic of the present species is well shown in the group of upper and
lower teeth preserved on the right side of the present instructive fragment of the skull,
(T. XXV and T. XXVI, fig. 2.) It includes, in an extent of 6 inches and 9 lines, six teeth
of the upper jaw; and, in an extent of 4 inches and a half, four teeth of the lower
jaw. Besides the teeth which have preserved nearly their natural positions in respect of
each other, there are three or four displaced teeth or fragments of teeth. Of the four
teeth of the lower jaw, the three largest, while they have kept nearly their natural
position to the teeth above, have slipped out of the groove of the lower jaw during its
downward displacement, instead of being separated to the same extent from the upper
teeth. In the lower jaw of the Cachalot, where the teeth are lodged in a wide groove,
and with the alveoli incompletely developed, they are easily dislodged when decom-
nosition has commenced, and may be stripped away with the firm gum, to which the
necks of the teeth adhere more strongly than their fangs do to the rudimental sockets.

The first of the six teeth of the upper jaw is completely formed, and shows the
quadrate root a little compressed in the transverse direction. The rough part of the
fang is that which is embraced by the sides of the alveolar grove ; the smooth portion
was probably surrounded by a soft slimy gum as far as the enamelled crown. The
tooth opposed to this in the lower jaw, and the crown of which passes, as usual,
external to it, is a young tooth, with the fang as yet incompletely formed and rounded :
its inferiority of size to the tooth above depends on this circumstance. The second
tooth above is not so far advanced in growth as the one which precedes or the four
that follow it; the crown and part of the fang of the last, m, of these are broken away,
and expose the germ of the young tooth, ¢, which had penetrated its cavity and was
about to displace it. The curve of the rough expanded fangs of the lower teeth is well
exhibited in the last two of these teeth.

The teeth of the Jchthyosaurus campylodon are large in proportion to the slenderness
of the elongated jaws, and offer, in this respect, a great contrast with those of the
Ichthyosaurus tenuirostris: they are even larger im proportion than the teeth of the
shorter and thicker jawed Ichthyosaurus communis and Ichthyosaurus lonchiodon, and
both the proportions and the form of the teeth determine the specific distinction of
the present Jchthyosaurus of the Chalk and Green-sand from any of the known species
from the older secondary strata. But there is no modification indicative of a departure
from the generic characteristics of the great Fish-lizard: on the contrary, so far as
these are manifested by the structure of the jaws, especially the undivided alveolar
groove, by the great proportional size of the premaxillaries, and by the thickly cement-
covered fangs of the teeth, these characters are rather in excess, and the last of the
Ichthyosaurs, far from progressing towards any higher and later form of reptile, might
be cited as a type of its peculiar genus.

CRETACEOUS FORMATIONS. 79

VERTEBR& OF ICHTHYOSAURUS CaMPYLODON. T, XXII.

Had no other part of the /chthyosaurus been discovered in the Chalk Formations
than the centrum of a vertebra, that alone would have sufficed to convince the
investigator, who had commenced his researches by descending from the more recent
to the older Formations, that some marine Saurian had existed totally distinct from any
other Reptile which he might have met with in the chalk ; if, indeed, a vertebra so far
departing from those of the Reptilia in general had not been mistaken for the vertebra
of a Fish. The most fish-like character of the Ichthyosaurus is the deep concavity
of both articular extremities of the centrum, fig. 3, and the shortness of the vertebra,
fig. 1, as compared with its breadth and height, fig. 2,in which proportion it resembles
the vertebree of the shark tribe. But the peripheral non-articular or free surface of
the vertebra is smooth and entire: the articular depressions for the neurapophyses
are shallow, and those for the ribs are situated on either one or two tubercles on each
side of the centrum. Such pair of costal tubercles would alone suffice to distinguish
the vertebra of the Ichthyosaurus from the biconcave vertebra of any fish. All the
general characters of the Ichthyosaurian vertebree are manifested by the specimen
figured in T. XXII.

It was discovered in the same mass of grey chalk at the base of Shakspeare’s
Cliff as the jaws and teeth figured in T. XXIII, and forms with these part of the
collection of W. H. Taylor, Esq. It corresponds in its dimensions with those fine
fragments of jaw, and might well have formed part of the vertebral column, wh’ch
supported a head four feet in length.

The substance of the bone is decomposed, and the surface studded with firmly
adherent pyritic matter. It appears to have come from the base of the tail, where the
costal tubercles become single. The surface of the articular concavity has the gentle
undulating disposition, convex at the periphery, before the deeper central concavity is
scooped out, as shown in the section, (T. XXII, fig. 3,) which is common to some other
species of Ichthyosaurus; but no specific character could have been deduced from this
fragment of the skeleton.

The vertebra figured measures 4 inches vertically across the articular concavity;
and | inch 10 lines longitudinally across the side. A smaller vertebra from the middle
of the tail measures 35 inches transversely, and 1} inch in antero-posterior extent.
The concavity deepens rather suddenly towards the centre.

Three more or less mutilated bodies of vertebrae, having similar proportions to
those of the Lchthyosaurus campylodon from the Dover Chalk, have been obtained from
the Upper Green-sand near Cambridge, where they are also associated with teeth of
the same species. They are preserved in the cabinet of James Carter, Esq., M.R.C.S.

80 FOSSIL REPTILIA OF THE

In the Jchthyosaurus tenwirostris, the length of the lower jaw equals at least fourteen
times that of the vertical diameter of the centrum of an anterior caudal vertebra; in
the Ich. communis and in the Ich. lonchiodon eleven times; in the Ich. intermedius ten
times. The jaws of the lchthyosaurus campylodon must have approached more nearly
to the proportions of those of the Jch. tenwirostris, than the other species above named,
and it is not unlikely that the lower jaw was thirteen times the length of the vertical
diameter of an abdominal or anterior caudal centrum.

Assuming such proportions, we may reckon the lower jaw to have been upwards
of four feet in length; and this calculation accords with that founded upon the
proportions of the fragments of the lower jaws above described.

One of the masses of chalk contains portions of several ribs, the longest being
about ten inches in length; the transverse section of these portions of rib is a regular
full ellipse, the fractured end of one of the least mutilated is 9 lines in its long
diameter, 6 lines in its short diameter; but some parts of the ribs are 1 inch in
breadth. Not any of these fragments show the opposite longitudinal impressions
that characterise some of the ribs in the Jchthyosaurus communis.

OrpER. PTHLROSAURIA, Owen.
Genus—PTERODACTYLUS, Cuvier.

The honour of having first made known the existence of remains of Pterodactyles
in the Chalk belongs to the able Secretary of the ‘ Palzeontographical Society,’ JAMES
Scott BowERBANK, Esq., F.R.S. This indefatigable Collector had the good fortune
to receive, in 1845, from the Chalk of Kent, the characteristic jaws and teeth, with
part of the scapular arch and a few other bones of a well-marked species of Pterodactylus,
and the discovery was briefly recorded in the ‘ Proceedings of the Geological Society
of London’ for May 14th, 1845,* with an illustrative plate. Mr. Bowerbank concludes
his Paper by referring to a large fossil wing-bone from the chalk, which I had previously
figured and described in the ‘ Geological Transactions,’+ and remarks that “‘if it should
prove to belong to a Pterodactyle, the probable expansion of the wings would reach
to at least eight or nine feet. Under these circumstances,” he says, ‘‘ I propose that

* The author there states that the specimens were “obtained from the Upper Chalk of Kent :”
Mr. Toulmin Smith, in his able paper “On the Formation of the Flints of the Upper Chalk’ in the
‘Annals of Natural History,’ vol. xx, p. 295, affirms that no Upper Chalk exists in the localities whence
those specimens came. They are from the Middle Chalk.

+ Second Series, vol. vi, 1840, pl. 39, fig. 1.

CRETACEOUS FORMATIONS. 3]

the species described above shall be designated Pterodactylus giganteus,” (loc. cit.,
p- 8.) Subsequent discoveries and observations have inclined the balance of pro-
bability in favour of the Pterodactylian nature of the fossils to which Mr. Bowerbank
refers.

These fossils are not, indeed, amongst the characteristic parts of the flying reptile ;
one is the shaft of a long bone exhibiting those peculiarities of structure which are
common to birds and Pterodactyles; the other shows an articular extremity which, in
our present ignorance of the different bones of the Pterodactyle, has its nearest
analogue in the distal trochlea of the bird’s tibia. These two specimens, which are
figured in the above-cited volume of the ‘Transactions of the Geological Society,’
Pl. 39, figs. 1 and 2, were, in fact, as | acknowledged in the Memoir, read April 26th,
1840, transmitted to me by the Earl of Enniskillen and Dr. Buckland, as being the
bones of a bird (p. 411), and my comparisons of them were limited to that class.

The idea of their possibly belonging to a Pterodactyle did occur to me, but it was
dispelled by the following considerations. The act of flight—the most energetic mode of
locomotion—demands a special modification of the vertebrate organisation, in that sub-
kingdom, for its exertion. Butin the class Aves, in which every system is more or less
adapted and co-adjusted for this end, the laws of gravitation seem to forbid the suc-
cessful exercise of the volant powers in species beyond a certain bulk; and when this
exceeds that of the Condor or Albatross, as, for example, in the Cassowary, the Emeu,
or the Ostrich, although the organisation is essentially that of the vertebrate animal
modified for flight, flight is impossible; and its immediate instruments, to the exercise
of which all the rest of the system is more or less subordinated, are checked in their
development, and, being unfitted for flight, are not modified for any other use. There
is, perhaps, hardly a more anomalous or suggestive phenomenon in nature than a bird
which cannot fly! A small section of the J/ammalia is modified for flight; but the
plan of the organisation of that warm-blooded class bemg less directly adapted for
flight than that of birds, the weight and bulk of the body, which may be raised and
transported through the air, are restricted to a lower range; and the largest frugivo-
rous Bat (Pferopus) does not exceed the Raven in size. The Reptilian modification of
the vertebrate type would seem to be still less fitted for any special adjustment to
aerial locomotion ; and, in the present day, we know of no species of this class that
can sustain itself in the air which equals a sparrow in size; this species, moreover, the
little Draco volans, sails rather than flies, upborn by its outstretched costal parachute in
its oblique leaps from bough to bough.

Of the remarkable Reptiles now extinct, which, like the Bats, had their anterior
members modified for plyimg a broad membranous wing, no species had been discovered
prior to 1840, which surpassed the largest of the Pferop?, or “ Flying-foxes,” in the
spread of those wings, and there was @ prior? a physiological improbability that the
cold-blooded organisation of a Reptile should, by any secondary modification, be made

11

82 FOSSIL REPTILIA OF THE

to effect more in the way of flight, or be able to raise a larger mass into the air, than
could be done by the warm-blooded mammal under an analogous special adaptation.

When, therefore, the supposed bird’s bone, T. XXX, fig. 4, was first submitted
to me by Dr. Buckland, which, on the Pterodactyle hypothesis, could not be the
humerus, but must have been one of the smaller bones of the wing, its size seemed
decisive against its reference to an animal of flight having a cold-blooded organisation.
The subsequent discovery of portions of the skull of the Pterodactyles, figured in
T. XXVIII, shows that the manifestations of Creative power in past time surpass the
calculations that are founded upon actual nature.

It is only the practised Comparative Anatomist that can fully realise the difficulty
of the attempt to resolve a Paleontological problem from such data as the two
fragments of bones first submitted to me in 1840. He alone can adequately appreci-
ate the amount of research imvolved in such a generalization, as that “there is no
bird now known, north of the equator, with which the fossils can be compared ;” and
when, after a wearying progress through an extensive class, the species is at length
found to which the nearest resemblance is made by the fragmentary fossil, and the
differences are conscientiously pointed out—as when, e. g., in reference to the humerus
of the Albatross, I stated that “it differs therefrom in the more marked angles which
bound the three sides,’—the genuine worker and searcher after truth may conceive
the feelings with which I find myself misrepresented as having “regarded the
specimens as belonging to an extinct species of Albatross.” My reference of the
bones even to the longipennate tribe of natatorial birds, is stated hypothetically, and
with due caution. ‘On the supposition that this fragment of bone is the shaft of
the humerus, its length and comparative straightness would prove it to have belonged
to one of the longipennate natatorial birds, equalling in size the Albatross,” (loc. cit.,
jb. ZANIS)}

Since the discovery has been made of the manifestly characteristic parts of the
genus Pierodactylus, in the Burham Chalk-pit, it has been objected that these bones
first discovered there, and described by me as resembling those of birds of flight,
“are so extremely f/cn as to render it most improbable that they could ever have sus-
tained such an instrument of flight as the powerful wing of the Albatross or of any
other bird: their tenuity is in fact such,” says the objector, “as to pot out their
adaptation to support an expanded membrane, but not pinions.”* This assertion
needs only for its refutation a simple reference to nature; sections of the wing-
bones of birds may be seen in the Museum of the Royal College of Surgeons, and
have been exposed to view, since the discovery of their structure, by the founder of
that Collection, in every Museum of Comparative Anatomy worthy to be so called.
To expose the gratuitous character of the objection above cited, I have selected for

* Mantell, ‘Wonders of Geology,’ 1848, vol. i, p. 441.

Qo

CRETACEOUS FORMATIONS. 3

illustration in T. XXXII, fig. 1, a section of the very bone that directly sustains the
large quill-feathers in the Pelican: its parietes are only half as thin as those of the
anti-brachial bone of the great Pterodactyle, figured in T. XXX, fig. 1: they are
thinner than those of the humerus figured in T. XXIX, fig. 1.

Hunter, who had obtained some of the long bones, with thin parietes and a wide
cavity, from the Stonesfield Slate, has entered them in his MS. Catalogue of Fossils, as
the “ Bones of Birds :” and perhaps no practical anatomist had had greater experience
in the degree of tenuity presented by the compact walls of the large air-cavities of the
bones in that class. Ofall the modifications of the dermal system for combining extent
of surface with lightness of material, the expanded feather has been generally deemed
the consummation. Well might the eloquent Paley exclaim :—‘“ Every feather is a
mechanical wonder—their disposition, all inclined backwards, the down about the stem,
the overlapping of their tips, their different configuration in different parts, not to
mention the variety of their colours, constitute a vestment for the body, so beautiful
and so appropriate to the life which the animal is to lead, as that, I think, we should
have had no conception of anything equally perfect, if we had never seen it, or can
imagine anything more so.” It was reserved for the author of the ‘Wonders of
Geology,’ to prefer the leathern wings of the Bat and Pterodactyle as the lighter form,

and to discover that such a structure, as is displayed in T. XXX, fig. 4, was “‘a
most improbable one to have sustained a powerful wing of any bird.”

Let me not be supposed, however, to be concerned in excusing my own mistake.
I am only reducing the unamiable exaggeration of it. Above all things, in our
attempts to gain a prospect of an unknown world by the difficult ascent of the frag-
mentary-ruins of a former temple of life, we ought to note the successful efforts, as
well as the occasional deviations from the right track, with a clear and unprejudiced
glance, and record them with a strict regard to truth.

The existence of a species of Albatross, or of any other actual genus of Bird,
during the period of the Middle Chalk, would be truly a wonder of Geology; not so
the existence of a bird of the longipennate family.

I still think it for the interest of science, in the present limited extent of induction
from microscopic evidence, to offer a warning against a too hasty and implicit con-
fidence in the forms and proportions of the purkingean or radiated corpuscles of bone,
as demonstrative of such minor groups of a class, as that of the genus Pferodactylus.
Such a statement as that these cells in Birds “have a breadth in proportion to their
length of from one to four or five; while in Repéi/es the length exceeds the breadth
of ten or twelve times,’* only betrays the limited experience of the assertor. In the
dermal plates of the Tortoise, e. v., the average breadth of the bone-cell to its length
is as one to six: and single ones might be selected of greater breadth.

* Mantell, ‘Wonders, &c.,’ vol. i, p. 441.

84 FOSSIL REPTILIA OF THE

With the exception of one restricted family of Ruminants, every Mammal, the
blood-discs of which have been submitted to examination, has been found to possess
those particles of a circular form: in the Camelid@ they are elliptical, as in birds and
reptiles. The bone-cells have already shown a greater range of variety in the
vertebrate series than the blood-discs. Is it, then, a too scrupulous reticence, to
require the evidence of microscopic structure of a bone to be corroborated by other
testimony of a plainer kind, before hastening to an absolute determination of its nature,
as has been done with regard to the Wealden bone, figured in the ‘ Geological Trans-
actions,’ vol. v, pl. xiii, fig. 6 2*

As a matter of fact, the existence of Pterodactylian remains in Chalk was not sur-
mised through any observation of the microscopic structure of bones that are liable to
be mistaken for those of birds, but by the discovery of the characteristic portions of
the Pterodactyle, defined by Mr. Bowerbank, as follows, in his original communication
of their discovery to the ‘ Geological Society of London,’ May 14th, 1845.

“JT have recently obtained from the Upper Chalkf of Kent, some remains of a
large species of Pferodactylus. 'The bones consist of—

1. **The fore part of the head, as far as about the middle of the cavitas narium,
with a corresponding portion of the under jaws,—many of the teeth remaining in their
sockets, (T. XXXI, figs. 1-5.)

2. “A fragment of the bone of the same animal, apparently a part of the coracoid,
(DS ROEX T, fie 72)

3. “ A portion of what appears to be one of the bones of the auricular digit, from
a Chalk-pit at Halling, (T. XXXII, fig. 8.)

4. “A portion of a similar bone, from the same locality as No. 1, (T. XXXI,
fig. 9.)

5. “ The head of a long bone, probably the tibia, belonging to the same animal as
the head, No. 1, (T. XXXI, fig. 10.)

6. “A more perfect bone of the same description, not from the same animal, but
found at Halling,” (T. XXXI, fig. 11.)

In a subsequent communication, dated December 1845, Mr. Bowerbank states, with
regard to the specimens, Nos. 5 and 6, which he supposed to be parts of a tibia, that
“on amore careful comparison with the figures of Pterodactylus by Goldfuss, I am
inclined to believe they are more likely to be portions of the ulna.”

* I would request the reader who may be desirous to exercise an independent judgement on such
facts as have been published on this point, to compare, for example, some of the cells figured by
Mr. Bowerbank, in Pl. i, fig. 9, of the ‘Quarterly Journal of the Geological Society,’ vol. iv, as being those
of the bone of a bird, with some of the wider cells, fig. 1, of the same plate, as being those of the
bone of a Pterodactyle; and contrast the want of a parallelism in the cells of the Wealden bone, fig. 9,
with the parallelism of the long axes of the cells in the bone of the Albatross, fig. 3.

+ See the Note, ante, p. 80.

CRETACEOUS FORMATIONS. 85

With respect to the long bone (T. XXXI, fig. 11), comparing it with that figured
in T. XXX, fig. 4, referred by me to Cimoliornis diomedeus, My. Bowerbank writes :—

“ Although the two specimens differ greatly in size, there is so strong a
resemblance between them in the form and angularity of the shaft, and in the com-
parative substance of the bony structure, as to render it exceedingly probable that
” and he concludes by remarking that “ if
the part of the head in my possession (see fig. 1), be supposed similar in its proportions
to that of Pterodactylus crassirostris,—and there appears but little difference in that
respect,—it would indicate an animal of comparatively enormous size. The length of
the head, from the tip of the nose to the basal extremity of the skull of P. crassirostris,
is about 43 inches, while my specimen would be, as nearly as can be estimated, 9%
inches. According to the restoration of the animal by Goldfuss, P. crassirostris would
measure, as nearly as possible, three feet from tip to tip of the wings, and it is
probable that the species now described would measure at least six feet from one
extremity of the expanded wings to the other; but if it should hereafter prove, that
the bone described and figured by Professor Owen belongs to a Pterodactyle, the
probable expansion of the wings would reach to at least eight or nine feet. Under
these circumstances, I propose that the species described above shall be designated
Pterodactylus giganteus,” (p. 8.)

In a subsequent Memoir, read June 9th, 1847, and published in the ‘ Quarterly
Journal of the Geological Society,’ February, 1848, ;Mr. Bowerbank gives figures of
the ‘“ bone-cells” from the jaw of a Pterodactyle (Pl. i, fig. 1), from the shaft of the
bone in question (ib., fig. 2), and from the femur of a recent Albatross (ib., fig. 13), in
corroboration of the required proof; and he adds :—* Fortunately the two fine
specimens from the rich collection of Mrs. Smith, of Tonbridge Wells, represented
by fig. 1, Pl. ii, in a great measure justify this conclusion, and in the bone a, which is
apparently the corresponding bone to the one represented by fig. 1 in Professor Owen’s
Paper, the head is very nearly ina perfect state of preservation,” (Op. cit., p. 5.)
Mr. Bowerbank, in his- explanation of Pl. ii, describes the two specimens above
mentioned, as:—“ Fig. 1. Radius and ulna of Pferodactylus giganteus, in the Cabinet of
Mrs. Smith, of Tunbridge Wells,” (Tom. cit., p. 10.) He proceeds to state, “there
are two other similar bones imbedded side by side in the Collection of Mr. Charles.
of Maidstone, of still greater dimensions than those from the Cabinet of Mrs. Smith,”
and he assigns his grounds for the conclusion, that ‘the animal to which such bones
belonged could, therefore, have scarcely measured less than fifteen or sixteen feet
from tip to tip of its expanded wings.” These bones are represented in T. XXIX
of the present Monograph.
~ The Committee of the British Association, for the Reform and Regulation of
Zoological Nomenclature, amongst other excellent rules, have determined, that :—

“Names not clearly defined may be changed. Unless a species or group is

they belong to the same class of animals ;’

S6 FOSSIL REPTILIA OF THE

intelligibly defined when the name is given, it cannot be recognised by others, and the
signification of the name is consequently lost. Two things are necessary before a
Zoological term can acquire any authority, viz. definition and publication. Definition
properly implies a distinct exposition of essential characters, and in all cases we
conceive this to be indispensable.*

Now with regard to the Pterodactylus giganteus, lalways understood Mr. Bowerbank
to apply the term to the species to which the long wing-bone first described by
me might appertain, under the circumstances of its being proved to belong to a
Pterodactyle, and my belief in this definition of his species was confirmed by the fact
of his subsequently figuring two similar and equal-sized bones in the ‘ Quarterly
Journal of the Geological Society,’ Vol. IV, pl. 2, fig. 1, (Proceedings of the Society
for June 9th, 1847) as the “radius and ulna of Pterodactylus giganteus.” So far as a
species can be intelligibly defined by figures, that to which the term yiganteus was, in
1845, provisionally, and in 1847 absolutely applied, seemed to be clearly enough
pointed out by the Plate 2, in the Work above cited. But with the large bones
appropriately designated by the term giganteus, some part of a smaller Pterodactyle,
including the portions of jaws first announcing the genus in the Chalk, had been
associated under the same name. Supposing those bones to have belonged to a young
individual of the Pferodactylus giganteus, no difficulty or confusion would arise. After
institutimg, however, a rigid comparison of these specimens, I was compelled to arrive
at the conclusion that the parts figured by Mr. Bowerbank, in Plate 2, figs. 1 and 2, of
Vol. II of the ‘ Quarterly Geological Journal,’ and the parts figured in Plate 2, figs.
i aand 0 of Vol. IV, of the same Journal, both assigned by Mr. Bowerbank to the
Pterodactylus giganteus, belonged to two distinct species. The portions of the scapula
and coracoid of the Pterodactyle (Pl. 1, fig. 2, tom. cit.) indicates, by its complete
anchylosis, that it has not been part of a young individual of the species to which the
large antibrachial bones (PI. 2, fig. 1, a and 4, tom. cit.) belonged, although it might
well appertain to the species to which the jaws (Pl. 1, fig. 1,) belonged. Two species
of Pterodactyle were plainly indicated, as I have shown in the Work by my lamented
friend, Mr. Dixon, ‘On the Tertiary and Cretaceous Deposits of Sussex,’ 4to, p. 402.
The same name could not be retained for both, and it was in obedience to this necessity,
and not with any idea of detracting an iota from the merit of Mr. Bowerbank’s original
announcement of the existence of a Pterodactyle in the Chalk, that I proposed the name
of conirostris for the smaller species, then for the first time distinctly defined and dis-
tinguished from the larger remains, to which the name giganteus had also been given
by Mr. Bowerbank. I proposed the name, moreover, provisionally, and with sub-
mission to the Committee for the Reform of Zoological Nomenclature, according to
whose rules I believed myself to have been guided.

* See their ‘ Report,’ Trans. of the British Association for 1842, p. 113.

CRETACEOUS FORMATIONS. $7

As, however, I have no personal feeling with regard to mere names, I shall
apply to the specimens of the jaws of the Pterodactyles, described in this Monograph,
the names by which Mr. Bowerbank first made those parts known to Geologists,
and before entering upon their descriptions shall premise a few remarks on the
Pterodactyles in general.

The Order Péerosauria includes species of flying reptiles, so modified in regard to
the structure and proportions of the skull, the disposition of the teeth, and the deve-
lopment of the tail, as to be referable, even according to the partial knowledge we
now possess of this once extensive group, to different genera.

M. von Meyer, e.g., primarily divides the Order into :—

A. Diarthri. With a two-jomted wing-finger.
Ex. Pterodactylus (Ornithopterus) Lavateri.
B. Tetrarthri. With a four-jointed wing-finger.
Ex. All the other known species of the Order.

These again are subdivided into :—

1. Dentirostres. Jaws armed with teeth to their ends: a bony sclerotic ring:
scapula and coracoid not confluent with one another:* a
short moveable tail.

Ex. Pferodactylus proper.

2. Subulirostres. Jaws with their ends produced into an edentulous point, pro-

bably sheathed with horn: no bony sclerotic: scapula and
. coracoid confluent : a long and stiff tail.

Ex. Pterodactylus (Ramphorhynchus) Gemmingt.-

The extremity of the upper jaw of the Pterodactylus Cuviert, Bowerbank, is
sufficiently perfect to demonstrate that it had a pair of approximated alveoli close to
its termination, and we may, therefore, refer it to the Dentirostral division.

In this division, however, there are species which present such different propor-
tions of the beak, accompanied by differences in the relative extent of the dental
series, as would, without doubt, lead to their allocation in distinct genera, were they
the living or recent subjects of the modern Erpetologist. In the P/erodactylus
longirostris, the first species discovered, and made known by Collini in 1784,{ the jaws
are of extreme length and tenuity, and the alveoli of the upper jaw do not extend so

* The condition of the scapular arch in the P. giganteus, Bow., P. conirostris, Mihi, demonstrates
the fallacy of this character.

+ Palzeontographica, Heft I, 4to, 1846, p. 19.

t Acta Academize Theodoro-Palatine, v, p. 58, Tab. v.

88 FOSSIL REPTILIA OF THE

far back as the nostril, T. XXVII, fig. 1. In the Pferodactylus crassirostris*, (ib. fig. 2.)
on the other hand, the jaws are short, thick and obtusely terminated; and the alveoli
of the upper jaw reach as far back as the middle of the variety which intervenes
between the nostril and the orbit, and which Goldfuss terms the “ cavitas intermedia.”

In the solid or imperforate part of the upper jaw anterior to the nostril the
Pterodactylus longirostris has twelve long subequal teeth, followed by a few of smaller
size: the same part of the jaw in the Per. crassirostris has but six teeth, of which
the first four are close together at the end of the jaw, and the first three shorter than
the rest. The “cavitas intermedia” in P. /ongirostris is much smaller than the nostril :
in the P. crassirostris it is larger than the nostril. Were these two species of
dentirostral Péerosauria to be taken, as by the modern Erpetologist they assuredly
would, to be types of two distinct genera, the name Pferodactylus should be retained
for the longirostral species, as including the first-discovered specimen and type of the
genus; and the crassirostral species should be grouped together under some other
generic name.

PrERODACTYLUS CuvIERI, Bowerbank. Tab. XXVIII, figs. 1—7.

‘Proceedings of the Zoological Society,’ January 14th, 1851.

The specimen of gigantic Pterodactyle, exhibited and so named by Mr. Bowerbank
at the meeting of the Zoological Society, January 14th, 1851, and which he has
confided to me for description in the present Monograph, consists of the solid anterior
end, z.¢., of the imperforate continuous bony walls, of a jaw, compressed, and
decreasing in depth, at first rapidly, then more gradually, to an obtusely poimted
extremity. As the symphysis of the lower jaw is long and the original joint oblite-
rated, and its depth somewhat rapidly increased by the development of its lower and
back part into a kind of ridge, in some smaller Pterodactyles, the present specimen,
so far as these characters go, might be referred to the lower jaw, and its relatively
inferior depth to the upper jaw in the P/er. giganteus, would seem to lead to that
conclusion. But the present is plainly a species which has a relatively longer and
more slender snout, and the convex curve formed by the alveolar border, slight as it
is, decides it to be part of the upper jaw. The lower jaw, moreover, might be
expected by the analogy of the smaller Pterodactyles to be flatter or less acute
below the end of the symphysis.

The specimen of Pterodactylus Cuvieri consists of the anterior extremity of the
upper jaw of seven inches in extent, without any trace of the nasal or any other

* Goldfuss, Beitriige zur Kenntniss Verschiedener Reptilien der Vorwelt, 4to, 1831, sec. i, Tabs. vii,
Vill, ix.

CRETACEOUS FORMATIONS. 89

natural perforation of its upper or lateral parietes, and corresponds with the parts
marked a, 6, T. XXVII, figs. 1 and 2. From the number of teeth contained in this
part, the Péter. Cwiert presents a much closer resemblance to the Pler. longirostris,
(ib., fig. 1,) than to the Pfer. crassirostris, (ib., fig. 2;) and, if the entire skull were
restored according to the proportions of the Péer. longirostris, it would be twenty-
eight inches in length.

But nature seems never to retain the same proportions in species that differ
materially in bulk. The great Diprotodon, with the dental and cranial characters of a
Kangaroo, does not retain the same length of hinder limbs as its living homologue ;
the laws of gravity forbid the saltatory mode of locomotion to a Herbivore of the bulk
of a Rhinoceros; and accordingly, whilst the hind legs are shortened, the fore limbs
are lengthened, and both are made more robust in the Diprotodon than in the
Kangaroo. The change of proportions of the limbs of the Sloths is equally striking
in those extinct species which were too bulky to climb: e.v., the Megatherium and
Mylodon. We may therefore infer, with a high degree of probability, when a longi-
rostral Pterodactyle much surpassed in bulk the species so called “ par excellence,”
that the same proportions were not maintained in the length of the jaws, and that the
species to which the fine fragment, (T. XXVIII, fig. 1,) belonged, far as it has exceeded
our previous ideas of the bulk of a flying reptile, did not sustain and carry through the
air a head of 2 feet 4 inches in length, or double the size of that of the Pelican. We
see, in fact, that the size of the teeth was not increased in the ratio of that of the
jaws.

Although the fractured hinder part of the jaw shows no trace of the commence-
ment of the wide nasal aperture, there is a plain indication that the jaws were less
prolonged than in the /#. /ongirostris, in the more rapid increase of the depth of the
jaw. Opposite the ninth tooth, e.g., the depth of the jaw equals two fifths of the
length of the jaw in advance of that tooth, whilst in the P¢. Jongirostris it is only
two sevenths. The contour of the upper border of the jaw in the P/erodactylus
Cuvieri differs from that in both the Pt. /ongirostris, Pt. crassirostris, and Pt. Gemming?,
in sinking more suddenly opposite the ninth, eighth, and seventh teeth, than along the
more advanced part of the jaw—a character which, while it affords a good specific
distinction from any of those species, indicates the hinder parts of the head, that
are wanting in the present specimens, to have been shorter, but relatively much deeper,
than in the P#. longirostris.

The first pair of alveoli (figs. 1 and 4, a) almost meet at the anterior extremity of the
jaw, (T. XXVIII, fig. 3,) and their outlet is directed obliquely forwards and downwards ;
the obtuse end of the premaxillary above those alveoli is about two lines across. The
palate, (ib., fig. 4,) quickly expands to a width of three limes between the second
alveoli, then to a width of four lines between the fourth alveoli; and more gradually,
after the ninth alveoli, to a width of six lines between the eleventh alveoli, a’: here
the palate appears to have been slightly crushed; but in the rest of its extent it

12

=

90 FOSSIL REPTILIA OF THE >

presents its natural form, being traversed longitudinally by a moderate median ridge,
on each side of which it is slightly concave transversely. It is perforated by a few
small irregular vascular foramina ; but the bony roof of the mouth is continued for an
extent of six inches without any trace of its interruption by the naso-palatal aperture.
There are no orifices on the inner side of the alveoli: the successional teeth, as
will be presently shown, emerge as in the Crocodile, from the old sockets, and not
as in certain Mammals and Fishes, by foramina distinct from them. The second
and third alveoli are the largest; the fourth, fifth, and sixth the smallest, yet they
are more than half the size of the foregomg; with which the rest are nearly equal.
The outlets of the alveoli are elliptical, and they form prominences at the side of
the jaw, or rather the jaw there sinks gently in between the alveoli, and is con-
tinued into the bony palate, without any ridge, the vertical wall bending round to
form the horizontal plate. The greatest breadth of the under surface of the jaw,
taken from the outside of the alveoli, varies only from seven lines across the third
pair to nine lines across the eleventh pair of alveoli; and from this narrow base the
sides of the jaw converge with a slight convexity outwards at the anterior half of
the fragment, but are almost plane at the deeper posterior half, where they seem to
have met at an acute superior ridge; indeed, such a ridge is continued to within
an inch of the fore part of the jaw, where the upper border becomes more obtuse.

The whole portion of the jaw consists of one uninterrupted bone—the pre-
maxillary; the delicate crust of osseous substance, as thin as paper, is traversed
by many irregular cracks and fissures, but there is no recognizable suture marking off
the limits of a maxillary or nasal bone. The bone offers to the naked eye a fine fibrous
structure, so fine as to produce almost a silken aspect: the fibres or strize being longi-
tudinal, and impressed at intervals of from two to six lines by small vascular foramina.

The first socket on the right side contains a young tooth which protrudes about a
third of an inch obliquely downwards and forwards, (fig. 1, a@:) the fifth socket on the
right side and the eighth on the left contain the germ of a younger tooth, the point of
which does not protrude beyond the socket; it les close to the inner wall of the socket
of the old tooth, from which it could have emerged, as in the Crocodile. Two fully
developed teeth, (figs. 5 and 6,) are preserved in the same block of chalk with the jaw.
One of these is 1 inch 4 lines in length, sabre-shaped, subcompressed, slightly bent,
and gradually diminishing in breadth from the widely-open base to the apex: this part
is broken off in both specimens, showing the crown to be composed of a compact hard
dentine, sheathed by a thin coat of shining enamel: about 9 lines of the basal part of
the present tooth, (fig. 5,) is coated by a thin layer of cement. The enamel is marked
by extremely fine longitudinal ridges, with an irregular or thready course, of unequal
length and with wide intervals, as shown in the magnified view, (fig. 7.) The second,
(fig. 6,) is a somewhat smaller tooth; having the same structure.

The unique specimen above described was obtained from the Burham Chalk-pit,
Kent, and forms part of the fine Collection of James 8. Bowerbank, Esq., F.R.S.

CRETACEOUS FORMATIONS. 91

PTERODACTYLUS GIGANTEUS, Bowerbank. Tab. XXXI.

PrpRODACTYLUS GIGANTEUS. Bowerbank. Proceedings of the Geological Society, May 14,
1845; in the ‘Quarterly Journal of the Geological
Society,’ February, 1846.
= coNIROsTRIS. Owen. Dixon’s ‘Geology and Fossils of the Tertiary
and Cretaceous Formations of Sussex,’ 4to, p. 401,
T. XXXVIII.

This specimen consists of the upper jaw, as far as the commencement of the
nostril, (T. XX XI, fig. 2, 2,) with the corresponding part of the lower jaw. The upper
jaw is a subcompressed, three-sided cone, with a more obtuse apex than in P/ero-
dactylus Cuviert, and more rapidly and regularly increasing in depth as it approaches
the nostrils, the sides converging at an acute angle as they ascend from the
alveolar border, arching over the apex of the jaw, but meeting within an inch from
this part at a ridge, which is rather more obtuse than that in Pf. Cuvier7, and
formed at a somewhat less acute angle, (figs. 3 and 4.) The surface of the bone
appears naturally to have been less even or level than m the larger species, and
the thin osseous plate is similarly fissured and cracked. The part appears, however,
to have suffered little compression ; the palate, where it 1s exposed at the back part
of the jaw, being entire, and presenting a concave longitudinal channel on each side
of a prominent median ridge: its breadth opposite the ninth alveolus is 8 lines; the
depth of the jaw at that part being 14 lines; the breadth of the base of the jaw, there,
outside the alveoli, is 11 lines. The sides of the jaw are plane, but sink in a little
between the alveoli, where they become continuous with the palatal surface. The
alveolar border of the jaw is slightly convex lengthwise along its anterior third, and is
continued straight along the rest of its extent. There are ten pairs of alveoli in the
part of the upper jaw anterior to the bony nostril, the alveoli being separated by
intervals about equal to their own diameter. In the P?. Cuvieri there are at least
twelve pairs of alveoli anterior to the nostril, and there may have been more, as there
are in the Pf. longirostris. In the Pt. crassirostris there are only six pairs of alveoli
in the corresponding part of the upper-jaw, and the fourth, fifth, and sixth, are
separated by intervals of thrice the diameter of the alveolus.

Such characters as these place in a strong light the specific distinctions of the
Pteroductyli compared. The species under consideration exemplifies in the Cretaceous
epoch the crassirostral group of the older secondary Pterosauria, as the gigantic
Pt. compressirostris does the longirostral group; the P?. Cuvier’ approaches nearer
a middle term between the two types of the groups in question. The length of the
jaw anterior to the nostril in the P¢. crassirostris, described by Goldfuss,* is 13 lines,

* Nova Acta Acad. Nat. Cur., tom. xv, pt. i, p. 63.

92 FOSSIL REPTILIA OF THE

that of the Pt. giganteus is 2 inches 3 lines; the total length of the head of the
Pt. crassirostris is 4 inches 8 lines, that in the P?. giganteus, restored on the same
scale, would be 9 inches, and the proportions on which this calculation is made are
much more likely to have been maintained, than those of the P#. longirostris, in
reference to the more gigantic Pt. Cuviert; but the teeth are absolutely shorter, and
relatively much smaller, than in the P#. crassirostris.

The lower jaw, fig. 5, has an obtuse rounded termination anteriorly like the upper
one, fig.4, but is a little narrower there, and is flatter, its under part being less convex
than the corresponding exposed part of the upper jaw is above: the median inferior
ridge behind this part is more suddenly developed than that upon the upper jaw, and
the progressively deepening sides of the lower jaw are bent inwards before they form
the ridge, being convex near the alveoli, and becoming concave at the base of
the ridge, in the transverse direction: and this modification does not appear to
be the result of accidental pressure. The solid or confluent symphysis has an
extent of more than 2 inches, but the bone is too much broken away at its back
part to determine its precise extent: it is evident, however, that the rami diverging
from it were of less vertical extent than the ridged part of the symphysis from which
they diverge, and this character is also shown in the lower jaw of the P?. /ongirostris,
and Pt. Gemmingi. On the right side of the lower jaw, which is best preserved, there
are nine alveoli, and part of a tenth, corresponding in size and spacing with those
above. ‘The inner alveolar wall extends so far inwards, horizontally, that if discovered
alone, it might well be mistaken for the palatal plate of an upper jaw. It is not
united with that of the opposite side to an extent corresponding with the bony palate
above; but to what extent the symphysis of the jaw is continued backwards, the
specimen does not allow to be precisely determined. This broad inner alveolar plate
of the lower jaw is slightly concave transversely, forming a wide longitudinal channel
about two lines and a half in breadth along the inner side of the alveolar border: to
the extent to which it may be united to the opposite plate, a median longitudinal
ridge will be formed dividing the two channels; and presenting a structure closely
corresponding with that of the palate above.

The teeth are preserved, in situ, in some of the alveoli, of both the upper and
lower jaws. The enamelled crown is a less elongated and narrow cone than in either
the Pt. Cuviert, or the Pt. crassirostris, and it is less compressed ; it does not exceed
one line and a half in length. The fang is longer, and after a slight expansion main-
tains the same diameter, or contracts a little towards its basal termination. The
smooth polished coronal enamel shows the same extremely fine raised strie, with an
irregular course and wide intervals, as in the teeth of Pt. Cwvieri7. The basal
cement has amore irregular external surface. The fractured tooth in the sixth alveolus
of the left side shows well the form of the transverse section at the base of the crown,
and the proportional size of the pulp-cavity. This, as usual, is occupied by a sparkling

CRETACEOUS FORMATIONS. 93

siliceous spath. I am not at present aware of any species of Pterodactyle in which
the teeth are so short and thick as in the P?. yiganteus, (see the magnified view,
fig. 6.) Those figured in Pl. 27, Vol. iii, 2d Series, of the ‘Geological Trans-
actions,’ on the supposition that they might belong to the Pterodactyle, appertain
to a species of Fish. The point of a successional tooth projects from the fore part
of the ninth socket on the right side of the upper jaw, from which its predecessor
has fallen, proving, as in the larger species, that the crowns of the successional teeth
do not emerge, as Cuvier surmised to be the case in P/. ongirostris,* from a distinct
orifice on the inner side of the socket of the old tooth, as in the Mammalia.

The substance of the osseous walls of the above-described portions of jaws is as
thin and delicate as in the foregoing species: it does not present the same fine
longitudinally striated surface as in the P¢. Cuvierz ; but it is similarly perforated by
numerous minute vascular foramina, which are largest and most abundant near the
alveolar border at the fore part of the jaw.

The unique specimen above described was discovered in the Burham Chalk-pit,
Kent, and is in the Collection of James Scott Bowerbank, Hsq., F.R.S.

ScaAPpuLAR ArcH AND BONES OF THE EXTREMITIES OF THE PTERODACTYLUS
GIGANTEUS, Bowerbank. Tab. XXXI, figs. 7, 8, 9, 1O—13.

Perhaps no part of the skeleton of the Pterodactyle more closely resembles in form
that of the bird, than the scapular arch: and in no specimen has this arch been better
preserved than in the Péterodactylus macronyx.t The scapula is shown in those specimens
to be long, sabre-shaped, and to form a moiety of the articular concavity for the head
of the humerus, and the coracoid to be stronger, straighter, and shorter than the
scapula, and with a subbifid protuberance near the articular surface for the humerus :
the opposite end of the coracoid terminates by a rather oblique truncation, but
without expanding: both the elements of the arch are anchylosed together, where they
meet at rather an acute angle to form the shoulder-joint. In the P?. crasszrostrist the
two bones appear not to have been anchylosed, the more slender and slightly curved
bone, 17, in Prof. Goldfuss’s plate, is called the coracoid, the stronger and straighter
one, 16, the scapula: but this determination seems to have been based upon the crushed
specimen, in which there has been sufficient displacement of parts to render it very
probable that the scapula and coracoid have suffered some change of position: the
fore part of 17, which I believe to be the scapula, shows a tuberosity near the articular
end, which forms an angle between that and the shaft of the bone: the coracoid, 16,

* Ossemens Fossiles, tom. vy, pt. ii, pp. 364, 367. Z

+ See Dr. Buckianp’s Memoir, ‘Geological Transactions,’ 2d Series, vol. iii, pl. xxvii, X, 9; and
Von Meyer, in the ‘ Nova Acta Acad. Nat. Curios.,’ tom. xv, pt. ii, Tab. Ix, fig. 8.

t Goldfuss, ut supra, T. VII, 16, 17.

94 FOSSIL REPTILIA OF THE

exhibits a stronger tuberosity near the same part; the sternal end of this bone is
slightly expanded and rounded. The length of the scapula is rather more than one-
third of that of the entire skull.

In the same block of chalk as that which contained the fore part of the jaws of
the Pt. giganteus, is preserved the confluent extremities of the right scapula and
coracoid, one third larger than the corresponding parts in the Pd. crassirostris, and
one-fourth larger than those in the P¢. macronyz. The portion of scapula, (T. XX XI,
figs. 7 and 8, 51,) includes thirteen lines of the humeral end of that bone; the fractured
part of the body showing that part to’be subcompressed, with the side next the ribs
slightly concave, the opposite side convex; the long diameter of this section of the
bone is 3 les; its short diameter 1 line; it expands as it approaches the shoulder
joint, and developes an obtuse oval tubercle, a, from its upper and inner border about
4 lines from the articular end; a low acromial ridge is extended from the outer side
of the bone, from near the origin of the tubercle, to the outer and fore part of the
glenoid cavity: the inner and posterior border is expanded into a third ridge which
joms a corresponding one from the same part of the coracoid. Of this bone, 52, about
ten lines is preserved: the transverse section exposed at the fractured end is oval,
and measures 35 lines by 2 lines; the expansion of the bone to form the shoulder-
joint is rapid. Besides the ridge sent off from the inner and back part to join the
one above mentioned from the scapula, there is a much stronger process, c, developed
from the under and fore part of the coracoid, as in that of the Pt. macronyx, between
which and the glenoid surface the bone is perforated by a narrow canal, the mner
outlet of which is just above the inner ridge. If we carry forwards the two straight
lines respectively parallel with the outer borders of the scapula and coracoid, they will
meet at an angle somewhat less acute than those in the P/. macronye. By a trace of
the original suture we may see that the coracoid has formed about two thirds of the
glenoid cavity, (fig. 7, 7:) the long diameter of that cavity measures 6 lines, its short
diameter 34 lines; in the direction of which it is flat above and slightly convex
below ; being concave only in the direction of its long axis; its contour is reniform,
the convex border being extended upon the acromial ridge. The long diameter of the
glenoid cavity in the P?/. macronyry measures 4 lines; and the absence of the
tuberosity on the scapula makes that end of the bone relatively more feeble than
in the present instance. As the parts are fully one third larger than those in the
Pt. crassirostris, we may estimate the skull of the present species according to the pro-
portions of the scapula to the skull in P¢. crassirostris, as having been about 7 inches
in length. Both the scapula and coracoid are hollow, the cavity being surrounded
by a very thin compact wall, and being subdivided by a few much thinner plates.

There is a fragment of a bone, (T. XXXI, fig. 9,) in the same block of chalk,
which, from its rapid expansion, I am induced to suspect to be part of the sternum:
its thickest part presents a coarse cancellous structure: from this part it expands
into a thin plate, of which, however, not enough remains to indicate its original form.

CRETACEOUS FORMATIONS. 95

Several portions of long bones figured in T. XX XI, may well belong, by their size,
to the same species as the portion of jaws, figs. 1 and 2, in the same plate: two of
them, figs. 11 and 12, are from a different locality, Halling pit, but from the same
formation—the Middle Chalk of Kent. As all these fragments, however, consist only
of the simple hollow shaft, I shall proceed with the description of the better preserved
specimens from the chalk which are referable to the genus Pterodactylus.

PTERODACTYLUS COMPRESSIROSTRIS, Owen. Tab. XXVII, figs. 8, 9, and 10.

This species is represented by two portions of the upper jaw, obtained from the
Middle Chalk of Kent, the hinder and larger of which includes the beginning of the
external nostril, (fig. 8, ».) The depth of the jaw at this part is 14 lines, whence
it gradually decreases, so as, at a distance of 3 inches in advance of this, to present
a depth of 10 lines, indicating a jaw as long and slender as in the Pterodactylus
longirostris, supposing the same degree of convergence of the straight outlines of the
upper and alveolar borders of the jaw to have been preserved to its anterior end:
that this was actually the case is rendered most probable by the proportions of the
smaller anterior part of the jaw, (T. XXVIII, fig. 8’ and 9’,) obtained from the same pit,
if not from the same block of Chalk, and which, with a vertical depth of 7 lines at its
hinder part, decreases to one of 6 lines in an extent of 1} inch in advance of that
part. The sides of the jaw as they rise from the alveolar border incline a little
outwards before they converge to meet at the upper border. This gives a very
narrow_ovoid section at the fore part of the larger fragment (fig. 9*), the greatest
diameter, at its lower half, being 4 lines, and the sides meeting above at a slightly
obtuse ridge. This very gradually widens as the jaw recedes backwards, where the
entireness of the walls of the smoothly convex upper part of the jaw proves that
the narrowness of that part is not due to accidental crushing. Had that been the
case, the thin parietes arching above from one side to the other would have been
cracked. The only evidence of the compression to which the deep sides of the jaw
have been subject is seen in the bending in of the wall above the alveoli, close to
the upper ridge, at the fore part of the fragment, in the crushed state of the palate
at that part, and in a slight depression of the left side of the jaw anterior to the
nostril.

In an extent of alveolar border of 33 inches, there are eleven sockets, the anterior
one on the right side retaining the fractured base of a tooth: the alveoli are separated
by intervals of about one and a half times their own diameter; their outlets are
elliptical, and indicate the compressed form of the teeth: they are about 2 lines in
long diameter, at the fore part of this fragment, but diminish as they are placed
more backwards, the last two being developed beneath the external nostril.

96 FOSSIL REPTILIA OF THE

The bony palate is extremely narrow, and presents, in the larger portion, fig. 10,
a median smooth convex rising between two longitudinal channels, which are bounded
externally by the inner wall of the alveolar border. There is no trace of a median
suture in the longitudinal convexity. The breadth of the palate at the back part of
the fragment is 8 lines, at the fore part it has gradually contracted to less than 3 lines,
but it is somewhat crushed here, (fig. 10, a.) The naso-palatine aperture commences
about half a line in advance of the external nostril, 3 inches behind the fore part of
the larger portion of the skull: its form and extent, so far as it is preserved, are
accurately shown in fig. 10, p, and it well exemplifies, in this specimen, the charac-
teristic extent of the imperforate bony palate formed by the long single premaxillary
bone in the present order of Saurians.

The fragment from the more advanced part of the jaw, fig. 8, contains five pairs
of alveoli, in an extent of 2 inches, these alveoli being rather larger and closer
together than in the hinder part of the jaw. Owing to the compression which the
present portion has undergone, the orifices of the alveoli are turned outwards; the
bony palate being pressed down between the two rows, and showing, probably as
the result of that pressure, a median groove between two longitudinal convex ridges ;
but the bone is entire and imperforate. The form of the upper jaw in the present
remarkable species differs widely from that of the two previously described specimens
from the Chalk, in its much greater elongation, its greater narrowness, and from
the P?. Cuvieri, more especially, in the straight course of the upper border of the
jaw, as it gradually converges towards the straight lower border in advancing to the
anterior end of the jaw. The alveoli, and consequently the teeth, are relatively smaller
in proportion to the depth of the jaw than in the P¢. Cuvieri, and are more numerous
than in the Pt. giganteus: they are, probably, also, more numerous than in the
Pt, Cuvier; although, as the whole extent of the jaw anterior to the nostril is not
yet known in that species, it would be premature to express a decided opinion on
that pomt. As we may reasonably calculate from the fragments preserved,
(T. XXVII, figs. 7 and 8,) that the jaw of the Plerodactylus compressirostris extended
seven inches in front of the nostril, it could not have contained less than twenty
pairs of alveoli, according to the number and arrangement of those in the two
portions preserved.

The osseous walls in both portions present the characteristic compactness and
extreme thinness of the genus: the fine longitudinal striz of the outer surface are
more continuous than in the P/. Cuvier7, in which they seem to be produced by a
succession of fine vascular orifices produced into grooves. The conspicuous vascular
orifices are almost all confined to the vicinity of the alveoli in the Pt. compressi-
rostris. 'This species belongs more decidedly than the P¢. Cuvieri to the longi-
rostral section of the Pferosavria: whether it had an edentulous prolongation of the
fore part of the upper and lower jaw, as in the P¢. Gemmingi, remains to be proved.

CRETACEOUS FORMATIONS. 97

In attempting to form a conception of the total length of the head of the very
remarkable species of Pterodactyle, represented by the portions of jaw above described,
we should be more justified by their form in adopting the proportions of that of the
Pt. longirostris than in the case of the Pt. Cuviert: but, allowing that the external
nostril may have been of somewhat less extent than in the Pt. longirostris, we may
still assign a length of from 14 to 16 inches to the skull of the Pterodactyle in
question, of which I have attempted an analogical restoration in T. XX VII.

It could not have been anticipated that the first three portions of Pterodactylian
skull, and almost the only portions that have yet been discovered in the Cretaceous
Formations, should have presented such well-marked distinctive characters one from the
other as are described and illustrated in the present Monograph. Such, nevertheless,
are the facts; and however improbable it may appear, on the doctrine of chances, to
those not conversant with the fixed relations of osteological and dental characters, that
the three corresponding parts of three Pterodactyles, for the first time discovered,
should be appropriated to three distinct species, I have no other alternative, in
obedience to the indications of Nature, than to adopt such determination.

The portions of the skull of the P#erodactylus compressirostris, like those of the
Pt. Cwiert and Pt. giganteus, were discovered in the Chalk-pit at Burham, Kent, and
are in the Collection of James Scott Bowerbank, Esq., F.R.S., to whose skill is due
the exposure of the palatal surface and the left side of the portion of the jaw, figured
in T. XXVIII, figs. 8 and 10.

Lone Bones or PrERoDACTYLUs CuvIERI. Tab. XXX, figs. 1, 2, and 3.

The bone which, from its size, and from the character of its external surface may
be, with most probability, referred to the largest of the above-defined species of
Cretaceous Pterodactyles, is that which forms the subject of figures 1, 2, and 3,
T. XXX. It was discovered in the Chalk-pit, at Burham, Kent, and is now in the
Collection of J. Toulmin Smith, Esq., of Highgate.

The length of the bone in proportion to its thickness is too great to be compatible
with its being the humerus; and indicates it to be either one of the antibrachial bones ;
or, more probably, from its similarity in shape to the long bones of most frequent
occurrence in smaller species, the first or the second phalanx of the elongated wing-finger.

One end of the bone is nearly entire, the other end is wanting, the total length of
the specimen being 143 inches. The longest diameter of the preserved extremity is
2 inches 3 lines, whence the shaft decreases to a diameter, in the same direction, of
1 inch, and then more gradually expands to a diameter of 1 inch 3 lines at the
fractured end. The shaft soon assumes a triedral figure, with the angles rounded off,
and the breadth of the narrowest side is shown in fig. 3. The contour of the best

13

9S FOSSIL REPTILIA OF THE

preserved end is shown at fig. 2*, where a and 4 may give the form and position
of natural articular surfaces, but there seems to have been some slight restoration
here: ¢ is a vacuity where the bone is deficient: the contour of the border of the bone
at a, fig. 2, which is obviously entire, satisfactorily indicates, however, the concavity
of the articular surface as shown at a. This, were the bone an ulna or a phalanx of
the wing-finger, would determine the end to be a proximal one: but if the bone were
a radius, the concavities @ and 4 might be adapted to some of the small carpal bones.
The presence of a pneumatic foramen, at p, figs. 1 and 3, would seem, however, to
show the extremity near which it is situated to be a proximal one, and if any trust could
be placed in the analogy of the bones of birds, the position of this pneumatic foramen,
with the double articular concavity, @ and 4, and the three-sided shape of the shaft,
would concur in leading to a reference of the bone to the ulna.

The side of the expanded proximal end shown in fig. 2 is slightly convex: that
shown in fig. 1 is almost flat, whilst the pneumatic foramen is situated in a deep and
narrow concavity or groove which forms the beginning, or the end, of the narrowest
of the three sides of the shaft of the bone. But the concavity is speedily changed,
as it passes down the shaft, for a convexity, which subsides to a flattened surface at
the middle of the shaft, as shown in fig. 2. The broadest side, shown in fig. 2,
becomes flattened in the shaft of the bone: the transverse section of which, four
inches from the entire end, is shown in fig. 3*, which also gives the thickness of the
compact osseous walls of the large air-cavity of the shaft; the thickness of these walls
is also shown at their fractured borders in figs. 1, 2, and 3; it exceeds, as might be
expected, that of the similarly sized pneumatic wing-bones of the gigantic Crane and
Pelican. The character of the surface of the bone closely resembles that of the portion
of the jaw of the Pterodactylus Cuvieri.

Lone BoNnEs OF PTERODACTYLUS COMPRESSIROSTRIS. Tabs. XXIV, XXX,
figs. 4 and 5.

In the reference of the long bones from the same locality or division of the Chalk
Formations as those from which the jaw-bones of the Pterodactyles have been derived,
the chief guide, at present, is the relative size of the parts.

It is not likely that one can err in associating the largest specimens of the
wing-bones, such as that above described, to the Pterodactyle, with the largest and
strongest jaw, especially when we find the same fine furrows and foramina giving a silky
appearance to the surface of both.

The smaller specimens appear by their more compact and smooth surface to belong
to the smaller species; but they may have been parts of smaller or younger individuals
of the larger species ; this, however, is the least likely of the conjectures to which, in the

CRETACEOUS FORMATIONS. 99

detached and fragmentary condition in which the part of the skeletons of these huge
winged reptiles have reached us, we are reduced in the attempts at their restoration.

In a mass of white chalk, about thirteen inches in length, in the collection of Thomas
Charles, Esq., are imbedded three portions of long-bones ; one of these (IT. XXIV,
fig. 1,) is seven inches in length, and shows a crushed articular extremity, 2 inches
2 lines in diameter, the shaft at the opposite fractured extremity being 1 inch 3 lines in
the longest diameter ; a second fragment (T. XXIV, fig. 3,) is 65 inches in length, with
a diameter of 8 lines at its smaller fractured end, and a diameter of 1 inch 3 lines at its
larger fractured end, to which it gradually expands ; the third portion (fig. 1, @ ¢,) may
be a part of the same bone, as fig. 3; it extends from close to the smaller fractured end
of that bone in the opposite direction, but in the same line, gradually expanding ; its
length being. 5 inches, and its diameter at the broader fractured end about one inch.

The largest portion of bone (T. XXIV, fig. 1,) presents at its expanded end two
surfaces, divided by a strong ridge, about one inch in length, the prominent summit
of which has been broken away. One of the surfaces is three times the breadth
of the other and is slightly concave transversely, becoming flat as it recedes from
the ridge to the tuberosity which terminates the end of the bone furthest from
the ridge. This tuberosity is subcompressed; many linear impressions, indicative of
the insertion of an aponeurosis or ligament, radiate from it upon the flat surface of
the bone: a slight concavity on the end of the bone bounds the tuberosity opposite
to the ridge; the rest of that end, including the articular surface, is, as usual,
destroyed. ‘The second surface is flat, and slopes away at an open angle from the
broader one. Below these surfaces, the outer layer of the thin, compact, osseous
wall, has scaled off, and the shaft has been fractured across obliquely, about three
inches from the expanded end. The thin wall of the shaft is then continued in broken
portions for about three inches lower down, and the rest of the shaft is represented by
the cast of its interior in the white chalk. This cast shows, on the surface which was
next the bone, several impressions, chiefly in an oblique direction, and nearly parallel
with one another; they are shallow and smoothly rounded at the bottom, and may be
presumed to have been left by ridges on the inner surface of the medullary or pneu-
matic cavity of the bone: blood-vessels merely would have perished before the chalk,
which must have been introduced into the cavities of these bones in a soft state,
could have hardened sufficiently to retain the impression.

With regard to the two other fragments, which are probably parts of an anti-
brachial bone of the same wing, there is even less character to be obtained from an
articular end than in the preceding fragment. On the supposition that the two
portions belong to the same bone, it must have been upwards of fourteen inches in
length. In the portion, T. XXIV, fig. 3, a part of the inner surface of the thin
compact wall of the medullary cavity of the bone is exposed: its smoothness is broken
by feeble linear elevations, which are reticularly disposed: it is in appearance very

100 FOSSIL REPTILIA OF THE

similar to what may be seen on the smooth inner surface of an air-bone in a large
flying-bird, the Pelican or Adjutant Crane, for example: but it is not peculiar to
bird’s bones. I find, for example, something of the same character on the smooth
inner surface of the medullary cavity of the tibia of a young gavial; and on the
same inner surface in a femur of a lion; only here there are minute vascular per-
forations leading to the thick parietes of the bone, which do not exist in the bird’s
bone, or in the fossil in question. The enlarged end of the portion of bone, T. XXIV,
fig. 3, shows evidence of a light open cancellous structure.

The thickness of the compact wall of the large medullary cavity does not exceed
half a line, as is shown in fig. 3; it is a little thicker towards the smaller end of
the large bone, figure 1. In neither case does it exceed the thickness of the shaft of
the humerus or ulna of the Pelican.

The transverse section of the smaller end of the portion of the largest bone,
T. XXIV, fig. 1, is a moderately long ellipse, rather more pointed at one end than
at the other, indicating an approach to something like a ridge or angle along the
corresponding side of the bone. The transverse section of the slender part of the
smaller fragments also gives a long ellipse. Neither of the bones show the three-
sided figure which characterises the long bone ascribed to the Plerodactylus Cuviert,
T. XXX, figs. 1—3, or that, fig. 4 of the same plate, originally figured in the
‘Geological Transactions,’ 2d series, vol. vi, Pl. 39, fig. 1.

The bone with which the larger portion, fig. 1, T. XXIV, is best comparable, is
the humerus, of which it may be the distal portion; but much is wanted in order
to attain to a satisfactory determination of it.

On the supposition that it is part of the humerus, and that the other two portions
on the same block of chalk are parts of one bone, this bone may be the shaft of the
radius.

T. XXX, fig. 5, represents, of the natural size, in the same block of chalk, portions
of two longitudinally juxtaposed bones, of nearly equal size, and of similar form, and
in this respect, resembling the radius and ulna of the Pterodactyle, as they are shown
in the Pf. Jongirostris of Colliniand Cuvier,* the P¢. medius of Count Munster,t and the
Pt. crassirostris of Goldfuss.t Of one of these bones an extent of upwards of nine inches
is preserved in three successive portions. About four inches of the other bone is
preserved. Both this and the chief part of the adjoining bone gradually expand to
the natural articular end, of which, however, only a small part is preserved in each,
showing a shallow smooth concavity; this which is best preserved in the bone, fig. 5*, d,
obliquely overlaps a small part of the longer bone. The long diameter of the
extremity of the shorter portion of bone is one inch five lines; from which the shaft

* Annales du Museum, t. xiii, pl. 31. + Nova Acta Acad. Nat. Curios., vol. xv, pt. i, T. VI.
t Ib., T. VII and VIII, 22, 23.

CRETACEOUS FORMATIONS. 101

gradually decreases to a diameter of nine lines. The side imbedded in the chalk is
convex; that exposed to view is nearly flat; but it is somewhat crushed; the longer
portion of the other bone is also too much crushed to give an idea of its natural shape.
Like the portions of bone in T. XXIV, these also present a thin wall of compact bone
encompassing a very wide medullary or pneumatic cavity ; the thickness of the wall
equals that of the same part of the ulna of the Pelican, T. XXXII, fig 1.

In the long bone, fig. 4, T. XXX, the original of the fig. 1, Pl. 39, of the
‘Geological Transactions,’ 2d series, vol. vi, the natural shape of the bone is better
preserved; but, unfortunately, only one small portion of the articular surface is
preserved at the expanded end, and this merely exhibits part of a shallow concavity,
with a thin well-defined border, fig. 4*,a. From this articular end to the opposite
fractured end of the shaft, the bone measures twelve inches. The breadth of the
expanded end is one inch and a half, whence the shaft gradually diminishes to a
diameter of nine lines at its middle part, and more gradually increases to a diameter
of eleven lines at the broken end.

The bone is very slightly bent lengthwise at its expanded end; it is straight in
the rest of its extent; its shaft is unequally three-sided, with the sides smooth and
flat, and the angles rounded off. The compact osseous wall is about the third of a line
in thickness, and incloses, as in the other specimens, an uninterrupted wide cavity.
One of the sides of the bone equals the extreme breadth of the shaft; a second
measures seven lines across, the third five lines; the second side increases in breadth,
at the expanded end, in a much greater degree than the third or narrowest side; and
this seems to have been indented by a natural fossa, and to have been perforated, at p,
for the,admission of air to the cavity, before terminating at the border of the articular
concavity. The true nature of this perforation, which I formerly apprehended might be
accidental in the fractured state of that end of the bone, and before the discovery of
other specimens, is illustrated by the presence of a similar perforation in the larger
sized corresponding bone fig. 1, »; and gives additional evidence of the remarkable
fact of the agreement of the flying-reptiles with birds in the extension of the air-cells
into the cavities of the bones.

Tab. XXIV, fig. 2, is the terminal portion of a long bone, with the articular end
again unfortunately destroyed, so as to deprive us of one of the best guides to the
determination of the fragment. So much of it as is preserved corresponds pretty
closely with the proximal end of the foregoing bone: it is subtriedral, with the angles
rounded off ; the broadest side is imbedded in the chalk ; the expansion of the exposed
surface is chiefly due to that of the next broadest side; and the narrowest side, as it
approaches the articular end, is impressed by a deep and narrow fossa, in which there
is an interruption of the thin walls of the bone in the corresponding position of that,
which, in the foregoing specimens, I have called a “foramen pneumaticum.”’ A portion
of the bone indicates the extension of a process beyond the articular cavity, which

102 FOSSIL REPTILIA OF THE

is a character of the proximal end of the first phalanx of the wing-finger, but no
part of the articular surface has been preserved.

A similar portion of the corresponding bone of the opposite wing is figured in
T. XXXII, fig. 2, and the more frequent occurrence of long bones with the subtriedral
shaft, showing a contraction and deepening of the narrowest of the three sides towards
one of the expanded ends of the bone, and the presence of the pneumatic foramen in
the groove so formed, would indicate them to be one of those bones that are present
in greatest number in the framework of the wing of the Pterodactyle, viz., a phalanx
of the singularly long and strong wing-finger.

The fragment of the shaft of a bone, with a wide cavity, T. XXXII, fig. 3, shows
a different shape from most of the long bones above described ; its transverse section
is given at fig. 3’; and from its shape, and the presence of a longitudinal ridge at
one side of the flatter and probably posterior part of the shaft, I am inclined to regard
it as having been part of a femur; it bears the same proportion to the diameter of the
humerus, T. XXIV, fig. 1, as the femur of the P/erodactylus crassirostris does to the
humerus, in the beautiful plates of the Memoir by Goldfuss, above quoted.

The fragments of long bones, with the best preserved articular extremity, are
those represented of the natural size in T. XXXII, figs. 4 and 5, the former of which
was originally figured in the ‘ Geological Transactions,’ 2d Series, vol. vi, pl. 39, fig. 2,
the latter in the ‘ Quarterly Journal of the Geological Society,’ vol. iv, pl. u, fig. 4.

Both these bones offer the closest resemblance to the trochlear modification of the
lower end of the tibia in the bird; and, if we might presume on that analogy, it would
be to the same bone in the gigantic Pterodactyle, that we should, also, refer them,
with the present indubitable evidence of the existence of volant reptiles of such
dimensions in the formation and localities whence the specimens in question have been
derived. But it is not likely that a reptile with distinct tarsal bones would have the
same modification of the distal end of the tibia as in the bird.

That which is the subject of fig. 5, in T. XX XII, was obtained by J. Toulmin Smith,
Esq. from a chalk-pit near Maidstone, and has not suffered the degree of compression
which distorts the specimen, fig. 4, T. XXXII, which was obtained by the Earl of
Enniskillen from the same pit. The obliquity of the two parallel, convex, narrow
condyles, which I suspected might be the effect of crushing in fig. 4, is shown to be
natural in fig. 5; the back part of each condyle is broken away, but their antero-
posterior extent is fortunately shown in fig. 4. The shaft is naturally compressed from
before backwards, as is shown by the section, fig. 5”, and by the side view fig. 5’.
There are two depressions and two rough elevations on the surface of the bone, fig. 5,
and between the latter a groove extends longitudinally, as if for the passage of a
strong tendon; the vacuity in the thin parietes of the bone above the condyle is, I am
assured by Mr. Smith, a natural one, which he himself exposed upon carefully removing
the chalk ; and it closely resembles the character of the “foramen pneumaticum” in a

CRETACEOUS FORMATIONS. 103

bird’s bone, but I am not aware of any in that class which is situated on the back part
of the distal end of the tibia. On the opposite side of the bone it presents a concavity,
which, however, is deepened by the yielding of the thin parietes of the bone at
that part.

In the crushed specimen, fig. 4, the convex contour of the condyles bounding the
deep trochlea, describes three fourths of a circle, and hitherto not any of the few well-
preserved articular ends of the bones of the Pterodactyles have exhibited this structure.

This remarkable trochlear joint may terminate either the femur, or the short and
thick metacarpal bone of the wing-finger.

Figures 6 and 7, T. XXXII, exhibit two portions of a long bone of a gigantic
Pterodactyle from the Green-sand near Cambridge, the shaft of which repeats the same
inequilateral triedral form as that of figs. 1 and 4, in T. XXX. The smaller fragment
of Pterodactylian bone, also from the Green-sand of Cambridge, fig. 8, T. XXXII,
indicates, by the strong and broad ridge, that it formed part of the proximal end of a
humerus; either of a younger individual, or of a species not larger than that called
Pterodactylus giganteus, by Mr. Bowerbank, and of which some of the long bones are
figured in T. XXXI.

The natural length of the different segments of the wing of the great Pterodactyles
of the Chalk may be estimated, according to their proportions in better preserved
specimens of the genus, if we can gain approximatively that of any one of the bones,
and more especially of the humerus. This I have endeavoured to do, with the
following results.

In the Pterodactylus macronyx, Pt. crassirostris, Pt. longirostris, the breadth of the
distal end of the humerus equals rather more than one fifth of its length, and according
to this proportion, the humerus, assigned to P/. compressirostris, Tab. XXIV, fig. 1,
may be restored, and would give a total length of ten inches and a half.

In the P#. macronyz, the length of the humerus is equal to three fourths of that of
the ulna; in P#. crassirostris it nearly equals one half; in the P¢. longirostris it equals
two thirds of the ulna; in Pt. longicaudatus it equals three fifths of the ulna. Taking
the mean of these proportions, which is nearly that in the P¢. longirostris, we may
assign fifteen inches as the probable length of the antibrachial bones of the Pé.
compressirostris. If the bone, T. XXX, fig. 1, be the ulna of the P¢. Cuvier?, it must
have been longer by some inches.

The species of smaller Pterodactyles above cited show a greater difference in the
proportions of the metacarpal bone of the wing-finger. In the P¢. macronyz this bone
is one half the length of the humerus: in the P¢. longirostris it is at least of equal
length with the humerus; the /¢. crassirostris and Pt. longicaudatus come nearer the
Pt. macronye in the proportions of this bone: we may therefore assign, without
hazarding an exaggeration, the length of six inches to both carpus and metacarpus of
the Pt. compressirostris.

104 FOSSIL REPTILIA OF THE

With regard to the first phalanx of the wing-finger, this bone in P#. macronyz is to
the humerus as 31 to 26; in the P?. crassirostris it is as 22 to 16; in the Pé. longirostris
as 17 to 10; in P?. longicaudatus as 2 to 1. In two of the above-cited species it is longer
than the ulna, in the other two it is shorter: we shall probably not greatly err if we
adopt the mean, and assign an equal length to the first phalanx with the ulna itself in
the Pt. compressirostris, viz. fifteen inches. In the P#. macronyx the second phalanx of
the wing-finger a little exceeds the length of the first : in the other species cited, it is a
little shorter ; we may assign, therefore, a length of 14 inches to the second phalanx
in the Pt. compressirostris. Supposing the long bone of the P#. Cwiert (T. XXX,
fig. 1) to be a phalanx of the wing-finger, it equals the dimensions above assigned to
those of the P?. compressirostris in its present mutilated state.

With regard to the proportions of the third phalanx, the P?¢. macronyz offers a
marked difference from the three other species here compared: its length being to
that of the first phalanx as 5 to 4, whilst it presents the reverse proportions in
the rest. So likewise, with regard to the last slender pointed phalanx of the wing-
finger, this exceeds the length of the penultimate phalanx in Pt. longicaudatus, but
falls short of that length in Pt. longirostris, the difference being very small in both
cases: the last phalanx is not preserved in the specimen of the P¢. macronyr,* nor
in that from which Professor Goldfuss has conjecturally restored the P¢. crassirostris.t

If we assume the penultimate and last phalanges of the Pf. compressirostris to have
been of equal length, and restore them according to the proportions of those of the
Pt. longirostris, we may assign the length of 26 inches to the two bones; but if the
proportions of the Pt. macronyx were preserved in the gigantic species, the last two
phalanges would be 30 inches in length. According to the former restoration the
length of the bones of one wing, in a straight line, would be 7 feet 2 inches; accord-
ing to the latter restoration, 7 feet 6 inches. We may be assured that we are within
the bounds of moderation, in assigning an expanse of 7 feet to each wing of the
smaller of the two great Pterodactyles of the Chalk, and supposing it to have had a
breadth of chest from one humeral joint to the other of 1 foot, it would measure
15 feet from the tip of one wing to that of the other, an expanse of pinions rarely
equalled, and still more rarely exceeded by the largest Albatross.t The Pterodactylus
Cuvieri was probably upborne on an expanse of wing not less than eighteen feet from
tip to tip.

* Geol. Trans., 2d Series, vol. ii, pl. xxvii. + Nova Acta Acad. Nat. Curios., tom. xv, pt. i, Tab. IX.

t Latham cites the following testimonies to the extent of the wings of the Albatross :—‘‘ Above ten
feet, (Foster’s Voyage, i, p. 87.) Ten feet two inches, called an enormous size, (Hawkesworth’s Cook’.
Voy., li, p. 627.) Eleven feet seven inches, (Parkinson’s Voyage, p. 82.) Twelve feet, MS., at Sir
Joseph Banks’s. One in the Leverian Museum expanded thirteen feet; and Ives mentions one, shot off
the Cape of Good Hope, measuring seventeen feet and a half from wing to wing, (See Voyage, p. 5.)’’
(Latham’s History of Birds, vol. x, p. 48, ed., 1824.)

CRETACEOUS FORMATIONS. 105

OrpeRr—DINOSAURIA.
Genus, IGUANODON.

Mr. W. H. Brenstep, of Maidstone, the proprietor of a stone-quarry of the
Shanklin-sand formation, in the close vicinity of that town, had his attention one day,
in May 1834, called by his workmen to what they supposed to be petrified wood in
some pieces of stone which they had been blasting. He perceived that what they
supposed to be wood was fossil bone, and with a zeal and care which have always
characterised this estimable man in his endeavours to secure for science any evidence
of fossil remains in his quarry, he immediately resorted to the spot. He found that
the bore or blast by which these remais were brought to light, had been mserted
into the centre of the specimen (which is figured in T. XX XIII), so that the mass of
stone containing it had been shattered into many pieces, some of which were blown
into the adjoining fields. All these pieces he had carefully collected, and proceeding
with equal ardour and success to the removal of the matrix from the fossils, he
succeeded after a month’s labour in exposing them to view, and in fitting the frag-
ments to their proper places.*

The quarry in which these remains were brought to light consists of many strata,
regularly alternating, of compact lime-stone, and of sand more or less loose. Each
stratum is of the thickness of from eight inches to twelve or fourteen inches, and the alter-
nation of the two beds is remarkably regular and equal. The bed in which the fossil
turtle Protemys serrata, described at pp. 15—19 of the present Monograph was discovered,
lies about fifteen feet below the Iguanodon bed,.and is remarkable for the accumu-
lations of the spiculz of sponges, with which it abounds. Not far below this is the
“ Atherfield clay,” which joins the ‘“ Wealden,” the junction of the two being scarcely
discoverable, owing to the similarity in texture and colour of the two clays.

* In a contemporary notice of this discovery, written with evident knowledge of the facts, and within
a month after they occurred, it is stated :—‘‘ By the great care bestowed upon them, however, by the very
intelligent proprietor of the quarry, Mr. W. H. Bensted, nearly all the detached pieces have been collected,
and the various bones carefully cleared from the rock which forms their matrix.’? (Philosophical Magazine,
July, 1834.)

Dr. Mantell, referring, in 1848, to this specimen in his ‘ Wonders of Geology,’ vol. i, p. 427, states :—
«The rock was shattered to fragments by the explosion, and the bones were broken into a thousand
pieces: but after much labour, I succeeded in uniting the several blocks of stone, and ultimately cleared
and repaired the bones, and restored the specimen to its present state.” As the specimen was presented
to Dr. Mantell, from whom it was purchased, with the rest of his Collection, by the British Museum, we

are doubtless indebted to his skill as well to that of its discoverer for the actual condition in which it may
now be studied.

14

106 FOSSIL REPTILIA OF THE

Amongst the portions of the skeleton recovered by Mr. Bensted, were fortunately
a portion of one tooth and the cast of a second in the matrix. ‘These were recognised
by him as being the teeth of the Iguanodon, which had previously been discovered in
the Wealden of Tilgate Forest,* and which had been described by Dr. Mantell in a
Paper printed in the ‘Philosophical Transactions’ for 1825; where that assiduous
explorer of the Wealden acknowledges the mode by which he obtained the required
information respecting them.

“As these teeth were distinct from any that had previously come under my notice,
I felt anxious to submit them to the examination of persons whose knowledge and
means of observation were more extensive than my own. I therefore transmitted
specimens to some of the most eminent naturalists in this country and on the continent.
But although my communications were acknowledged with that candour and liberality
which constantly characterise the intercourse of scientific men, yet no light was thrown
upon the subject, except by the illustrious Baron Cuvier, whose opinions will best appear
by the following extract from the correspondence with which he honoured me :—

“Ces dents me sont certainement inconnues; elles ne sont point d’un animal
carnassier, et cependant je crois quelles appartiennent, vu leur peu de complication,
leur dentelure sur les bords, et la couche mince d’émail qui les revét, a lordre des
reptiles. A l’apparance extérieure on pourrait aussi les prendre pour des dents de
poissons analogues aux tetrodons, ou aux diodons: mais leur structure intérieure est
forte différente de celles-la. N’aurions-nous pas ici un animal nouveau! un reptile
herbivore? et de méme qu/actuellement chez les mammiferes terrestres, c’est parmi
les herbivores que l’on trouve les espéces a plus grande taille, de méme aussi chez les
reptiles d’autrefois, alors quils étaient les seuls animaux terrestres, les plus grands
d’entr’eux ne se seraient-ils point nourris de végétaux? Une partie des grands os que
vous possédez appartiendrait a cet animal unique, jusqu’a present, dans son genre.
Le temps cozfirmera ou 7firmera cette idée, puisquil est impossible qu’on ne trouve
pas un jour une partie de la squelette réunie 4 des portions de machoires portant des
dents. C’est ce dernier objet surtout quwil s’agit de rechercher avec le plus de
perséveérance.’

‘«These remarks,” Dr. Mantell proceeds to say, “induced me to pursue my investi-
gations with increased assiduity, but hitherto they have not been attended with the
desired success, no connected portion of the skeleton having been discovered. Among
the specimens lately connected, some, however, were so perfect, that I resolved to
avail myself of the obliging offer of Mr. Clift (to whose kindness and liberality I hold
myself particularly indebted), to assist me in comparing the fossil teeth with those of
the recent Lacertee in the Museum of the Royal College of Surgeons. The result of
this examination proved highly satisfactory, for in an Iguana which Mr. Stutchbury

* «The first specimens of the teeth were found by Mrs. Mantell in the coarse conglomerate of the
Forest, in the spring of 1822.”” (Mantell, ‘Geology of the South-East of England,’ 8vo, 1833, p. 268.)

CRETACEOUS FORMATIONS. 107

had prepared to present to the College, we discovered teeth possessing the form and
structure of the fossil specimens.” (Phil. Trans., 1825, p. 180.) And he afterwards
adds :—‘the name Iguanodon, derived from the form of the teeth, (and which I have
adopted at the suggestion of the Rev. W. Conybeare,) will not, it is presumed, be
deemed objectionable.” (Ib., p. 184.)

The fortunate discovery by Mr. Bensted was one of those which Baron Cuvier’s
prophetic glance saw hidden in the womb of time, and the birth of which has served
to verify his sagacious conjecture, that some of the great bones collected by Dr. Mantell
from the Wealden of Sussex, belonged to the same animal, unique in its genus, as the
teeth; and also to confirm the accuracy of their discoverer’s determination of the
clavicle, femur, and tibia, figured and described by him in the ‘ Geology of the South-east
of England,’ 8vo, 1833, pp. 307—10, Pls. If and III.

In the work entitled ‘ Wonders of Geology,’ in which the author gives a miniature
view of the parts of the skeleton of the Iguanodon, recomposed by Mr. Bensted and
himself, he points out several “vertebrae of the back and tail,” ‘ribs,’ “the two
clavicles,” “one of the bones (radius) of the fore-arm (subsequently recognised by
Mr. G. B. Holmes, of Horsham, and by Dr. Mantell, as the humerus),” “two
metacarpal bones,’ “ the two ossa ilia,” “the right and left thigh-bone, or femur,” “a
leg-bone, or “dia,” “ bones of the toes (metatarsal and phalangeal) of the hind feet.”
The parts marked “6” as metacarpals, are those named “radius” and “ulna” in
T. XXXIV.

The femora measure each thirty-three inches in length, and one of them originally
stood in a vertical position, as regards the strata, which are nearly horizontal ; and it
projected from the solid limestone bed, which embraced its lower extremity, and passed
nearly through the superincumbent bed of sandstone. The author of the ‘ Notice of
the Discovery of the Iguanodon in the Maidstone Quarry,” infers from this circum-
stance a proof, ‘that these two beds, now so different in consistency, were, in the one
case, ‘loose sand, and in the other, ‘ tenacious mud, at the period when this shattered
and decomposing body of the Iguanodon sank to the bottom of the sea, and became
covered up by an abundant deposition.” Dr. Buckland remarks, with reference to the
discovery of this skeleton, in strata of the cretaceous period :—‘ That both the sand
and the limestone are marine formations there can be no doubt; for though wood and
vegetable substances are not uncommon in these beds, yet the limestone abounds in
ammonites, shark’s teeth, and other sea productions, while a small sea-shell was also
found fixed upon one of the bones of the Iguanodon.”’ Both strata of the Kentish Rag
are now satisfactorily proved to belong to the neocomian or lower division of the
Greensand formation, which intervenes between the Wealden and the upper Greensand,
or in some parts of England between the Wealden and the Chalk. Dr. Buckland has
remarked, in reference to this discovery of the Iguanodon, that it “shows that the

* ©Philos. Magazine,’ loc. cit.

108 FOSSIL REPTILIA OF THE

duration of this animal did not cease with the completion of the Wealden series. The
individual from which this skeleton was derived had probably been drifted to sea, as
those which afforded the bones found in the fresh-water deposits subjacent to this
marine formation had been drifted into an estuary.”’*

One of the chief advantages of Mr. Bensted’s remarkable discovery, is the demon-
stration which it affords of the vertebral characters of the Iguanodon,—an important
evidence of organisation, the difficulty of obtaining which will be appreciated by
reference to my ‘ Report on British Fossil Reptiles,’+ in which descriptions of the
various vertebree that had been found in the Wealden up to the year 1841 are given.

In the point of view in which I have had this remarkable and unique collection of
the remains of one and the same animal figured, there are four vertebra with their
bodies in natural juxtaposition at the upper corner opposite the right hand, and the
same number a little dislocated at the lower corner of the slab. The latter show the
characteristic neural arch in the best state of preservation, and the second of these
vertebre is represented of the natural size in T. XXXV.

In neither of these series, nor, indeed, in any part of the slab, is there a vertebra
with a parapophysis, or articular tubercle or impression for a rib, upon the centrum,—a
character indicative of one from the neck or anterior part of the thorax. The whole
of the exposed outer surface of the centrum, save the two extremities, is smooth or
“‘non-articular,” as in the middle and hinder parts of the trunk in the Crocodilia.
Both the terminal or articular surfaces of the centrum are slightly concave, and with
a nearly circular contour, with the vertical diameter slightly predominating (T.
XXXVI); the sides of the centrum rapidly contract as they recede from the articular
ends towards the middle of the vertebra, and are chiefly remarkable for the almost
plane surface which they form as they converge towards the lower surface of the
centrum, the middle part of which is thus somewhat wedge-shaped, but with the lower
border obtuse, and slightly concave lengthwise, as shown in T. XXXV.

The converging sides are, however, slightly convex vertically, more concave
transversely ; the free surface is traversed by fine longitudinal linear impressions.
The neurapophyses have coalesced with each other, and the neural spine (xs) above,
forming a remarkably broad and lofty neural arch, the base of which (x x) is still
articulated by suture im this young Iguanodon to the centrum. In a few of the
vertebree this persistent suture has permitted a dislocation of the arch. The base of the
neurapophysis is coextensive with the centrum lengthwise, and is developed inwards,
transversely, so as almost to meet its fellow and circumscribe the neural canal. As
the neurapophysis ascends it diminishes at first, in both diameters, and then again
increases above the neural canal, and expanding above into a broad and strong plat-
form, x x», coalescing with its fellow, which surpasses the base of the neurapophysis

* Bridgwater Treatise, vol. i, p. 241.
+ Transactions of the ‘British Association,’ 1844, pp. 84—133.

CRETACEOUS FORMATIONS. 109

both in length and breadth. The platform is chiefly supported by a buttress-like
ridge, which rises nearly vertically from the hinder and outer angle of the base of the
neurapophysis, and gradually expands as it ascends, inclining a little forwards to blend
with the under part of the overhanging platform. A transverse process, p, answering
to the lower one or “ parapophysis,” in the vertebra of the Crocodile (T, V, fig. 3, p,)*
extends from the side of the neurapophysis anterior to the buttress; its base presenting
the form of an oval with the long axis vertical, and the small end upwards from which
a smooth, convex prominence extends upwards and forwards, and subsides on the base
of the anterior zygapophysis, which is developed from, or terminates, the fore-part of
the neural platform. This transverse process is very short, and afforded an articular
surface for the head of the rib. The second transverse process, answering to the
upper one or “ diapophysis”’ in the vertebra of the Crocodile (d, T. V, fig. 3)+ which
has been broken away in this specimen, is better preserved in the vertebra nearest the
upper border of the slab in the T. XX XIII, and in a few other detached vertebre.
The anterior zygapophyses scarcely project as distinct processes from the neural
platform, but seem to form the natural anterior boundary of that part; their thickness
gradually diminishes to an edge anteriorly, and their flat oval articular surfaces look
obliquely upwards and inwards. The posterior articular surfaces are developed from
the under and back part of the neural platform, and look downwards and outwards,
over-hanging the hinder surface of the centrum. This part of the neural arch has
been somewhat crushed and depressed in the vertebra which best shows its characters
amongst those in Mr. Bensted’s specimen; but one may see that the plane from which
the neural spine rises has sloped from behind downwards and forwards. The base of
the neural spine is coextensive with the neural platform ; from the middle line of which
it risés, but it contracts as it ascends, and inclines backwards; its height is shown to
equal that of the rest of the vertebra in one that lies between the humerus and femur:
although it has there suffered fracture; in the other specimens the broken summits of
the spines have not been preserved.

In the characters above defined we may plainly recognise a vertebra differing
from any of those that have been previously described; from those of the Crocodiles
and Gavials (T. IV, V, IX, and X){ in the flattened articular ends of the centrum;
and by the same character from those of the Ophidian (T. XIII and XIV),§ and
Lacertian (T. VIII, IX, and X)|| reptiles which we have hitherto met with in the
Tertiary and Cretaceous deposits; it is equally distinct from the biconical and short
vertebree of the Ichthyosaurus (T. XXII). Were the centrum of the Iguanodon’s
vertebra (T. XXXV) to be found detached from the neural arch, it might not be so
easy to distinguish it from that of a dorsal vertebra of a Plestosaurus, which is similarly

* Monograph on the Reptiles of the London Clay, pp. 33—36. + Op. cit.
t Monograph on the Reptiles of the London Clay, Part i. § Ib.
|| Monograph on the Reptiles of the Cretaceous Formations.

110 FOSSIL REPTILIA OF THE

characterised by nearly flattened articular extremities; but although the vertebre are
very variable in their proportions as to length and breadth in the different species of
Plesiosaurus, 1 have hitherto found none that combine the same antero-posterior
diameter with the nearly flattened, inferiorly converging, sides of the dorsal centrum,
as in the Iguanodon. When, however, the entire vertebra can be compared, or the
chief characters of the neural arch of the Iguanodon, with the tallying parts in the
Plesiosaurus, important differences present themselves. In the cervical region of the
Plesiosaurus, the neural arch is comparatively low and simple, and sends off no other
processes save the zygapophyses and spine: in the dorsal region a diapophysis is
superadded; but this alone offers an articular surface for the rib, and there is not
any rudiment of parapophysis or of a parapophysial articulation for the head of the
rib, such as is shown at p, T. XX XV. In the presence of this lower transverse process
with the surface for the head of the rib, in the Iguanodon, developed either from the
side of the centrum (as in the anterior dorsal vertebree), or from the side of the neural
arch (as in the middle dorsal vertebra), we have a character* distinguishing it from
Ophidia, Lacertilia, and Enaliosauria, whilst in the strong bony platform, in which the
summit of the neural arch expands, with its supporting buttresses, we have an
additional character distinguishing it from all known Crocodilia; and indicative of a
distinct order of reptiles.

The importance of the characters deducible from Mr. Bensted’s invaluable dis-
covery, will be plainly manifested when the detached vertebree and other fragmentary
remains of large Saurians come to be described in the ‘ Monograph on the Wealden
Reptiles,’ and I proceed next to notice those of some caudal vertebree which are well-
preserved in the Maidstone specimen ; they are marked ‘c. vertebre’ in T. XXXIV, and
one of the most perfect is figured of the natural size in T. XXXVII. The centrtm is
more compressed than in the trunk, its articular ends are less expanded, but the
flattened character of the inferiorly converging sides of the centrum being retained,
this part presents in a more marked degree the wedge-shaped figure ; the converging

* First made known in my ‘Report on British Fossil Reptiles,’ Trans. Brit. Association, 1841,
p- 127. ‘‘In the interspace of the two buttresses of the anterior dorsal vertebree there is a large oval
articular surface, convex at the anterior, and concave at the posterior part, which has afforded a lodgement
to the head of the rib.” The nature of the part affording this surface is described in the next page as
‘the transverse process’’ which ‘‘ extends from the side of the neurapophysis.”” At the commencement of
my ‘Report’ I defined the “transverse processes”’ as being “‘ of two kinds, superior and inferior,” (p. 48,)
but I did not, in that ‘Report,’ specify them by the names “diapophysis’’ and “parapophysis:” the
process in question for the head of the rib is the ‘‘parapophysis.”” The author of the Appendix to
Dr. Mantell’s Paper, in the ‘ Philosophical Transactions,’ 1849, assuming the ‘‘ upper transverse process”
to be the one indicated in my description of the fractured vertebra, No. 2160, imputes to me what he
conceives to be an error (p. 291); but the error lies in his assumption. It is one amongst many instances
of the necessity of abandoning the vague term ‘transverse process,’ and the advantage and propriety of the

definite names “diapophysis” and ‘ parapophysis,” which I have been in the habit of using since the
publication of my ‘ Report’ in 1841.

CRETACEOUS. FORMATIONS. 111

sides, however, are separated below by a broader quadrate tract which is slightly
concave transversely, and more so lengthwise, with each of its angles developed into
an articular hypapophysis, y' y’, for the junction of a portion of the base of a hemal
arch. This part, which is shown in T. XXXIII and XXXIV, near the middle of the
upper border of the slab, consists, as usual, ofa pair of ‘‘ heemapophyses,” but they are
confluent with one another, not only where they form the base of the long hzemal spine,
but also at their opposite extremities ; and the hinder hypapophysial surfaces, »' y,/
which are the largest, also run into one another across the middle line. The articular
end of the centrum, fig. 2c, presents something between a quadrate and an elliptical
form, with the long axis vertical; it is a little depressed within the border. The
neural arch is anchylosed to the centrum; a rudiment of a parapophysis appears at
the side of its base; the diapophysis rises above and behind this, and extends
obliquely upwards, outwards, and backwards; its extremity is broken off. The
zygapophyses, z z, figs. ] and 2, are reduced to short tuberosities, without articular
surfaces in this region of the spme; and the neural platform and its buttresses are
quite suppressed. The summit of the neural spine is broken away.

Amongst the portions of ribs that are preserved, some show clearly not only the
head but the neck and an articular tubercle; superadditions, which at once remove the
Iquanodon from the /guana and allits Lacertian congeners, and show the nearer affinity
of the great Dinosaur to the Crocodiles; in one of the specimens near the upper part
of the slab, as figured in T. X XXIII, there is an indication of the upper part of the
neck of the rib rising and bifurcating near the tubercle, whence it is continued as two
ridges which form an anterior and posterior margin, as it were produced and overhanging
the body of the rib. This character may not be without its value in detecting and
determining fragments of ribs, which are common among the fossils of the strata
containing the remains of great reptiles.

Both the bones, answering to those from the Wealden of Tilgate, which Cuvier
thought “might be a clavicle,’* are preserved in the Maidstone specimen, haying
the same long, slender, triedral shaft slightly expanded, flattened and bent at one
extremity ; more expanded, flattened, and bent at an open angle at the opposite end ;
with a short pointed process sent off at the angle, and a broad subquadrate flattened
plate projecting from the same border of the bent and expanded end, which has a
truncate termination. In the Cyclodust lizard I find the clavicle is bent at an open
angle, but nearer its middle part; and the difference between this and the nearly

* Quoted by Dr. Mantell, in ‘ Geology of the South-East of England,’ 1833, p. 308.

+ This is the Lizard referred to in the following passage of Dr. Mantell’s Paper, in the ‘ Philosophical
Transactions,’ 1841, p. 138. ‘In a very small Lizard in the Hunterian Museum, Mr. Owen pointed out
to me a bone attached to the coracoid and omoplate, that bore some analogy to the one in question :”’
it bears sufficient analogy to support the conclusion in the text, but lends no countenance whatever to the
idea of the fossil in question being a peculiar superaddition to the Saurian skeleton, requiring a new name.
The ‘os Cuvieri”’ is, in fact, abandoned in the Paper, in the ‘Phil. Trans.,’ 1349.

112 FOSSIL REPTILIA OF THE

straight clavicle of the Jywana, Amblyrhynchus, and some other lizards, justifies the
expectation of some unexampled modifications of that variable bone in a great extinct
reptile of a different order.

For a knowledge of the bone, called “scapula” and “humerus,” in T. XXXIV, I
am indebted to Mr. George B. Holmes, of Horsham, who, in March, 1847, transmitted
to me a beautiful drawing of both bones, together with the coracoid in natural juxta-
position with the humerus, discovered “in one block of stone, with other bones of the
same individual” in Tower Hill Pit, near Horsham. That gentleman, whose collection
of the Wealden Fossils in his neighbourhood is one of the most instructive extant, had
correctly determined their nature, and named them in the drawing which he sent
to me ‘‘ Humerus, Scapula, and Coracoid bone of the Iguanodon.”

Dr. Mantell published similar determinations of homologous bones, in the ‘ Philo-
sophical Transactions’ for 1849. This part of the skeleton of Iguanodon may, therefore,
be regarded as definitely restored.

The scapula in the Maidstone specimen, T. XX XIII, lies broken across the femur :
it is a long, narrow, flattened bone gradually expanding to its free end, more suddenly
towards its articular end; but this is too much mutilated to give its true character in
the specimen in question: it will be described from Mr. Holmes’s beautiful specimen
in the ‘ Monograph of the Fossil Reptiles of the Wealden.’

The humerus (see T. XXXIV) is shorter than the scapula, and much shorter than
the femur, its relative proportions to which are the same in the Iguanodon, as in the
Teleosaurus (see T. XI, Monograph on the Crocodilia of the London Clay), and, with
the vertically developed tail of the Iguanodon indicate the aquatic habits of that
gigantic reptile. The head of the humerus is hemispheroid, and projects between two
sub-equal tuberosities ; a deltoid ridge is continued nearly half way down the bone
from the outer tuberosity, and, where it subsides, the shaft is bent a little inwards,
contracts, and then again expands to the distal condyles, which are rounded and pro-
minent, with a moderately deep depression between them at the back, which is the
part of the bone exposed in the Maidstone specimen.

The radius and ulna lie with their proximal ends next the right hand upper corner
of the slab of the Maidstone specimen ; the latter being distinguished by its prominent
olecranon, which is rounded as in the great Monitor (Varanus niloticus). I shall reserve
the description of the metacarpal and metatarsal bones for a succeeding Monograph, and
shall only observe, here, that the claw-bones marked “ ungual phalanx” in T. XXXIV,
though varying in their proportions in the two specimens preserved, are broader, more
depressed, and less incurved than those of other known Saurians.

The ilium which lies detached near the lower border of the slab in the Maidstone
specimen, is the left one, with its sacral articular surface or inner surface uppermost,
the extent of which plainly indicates the great length of the sacrum in the Iguanodon,
as compared with existing Lizards, since it equals the antero-posterior diameter of five

CRETACEOUS FORMATIONS. 113

of the dorsal vertebrae ; the part of the bone which is prolonged backwards beyond
the articular part is slender, and terminates in an obtuse point. The right ilium,
which is overlapped by one of the clavicles, shows that the anterior end bends
outwards in the form of a thick tuberosity, and the expanded portion contributes by
its lower border the usual share in the formation of the acetabulum.

The two femora (T. XXXIV, femur) well exemplify the characteristic peculiarities
of this bone in the Iguanodon: its inwardly projecting hemispheric head, its much
flattened trochanter, the compressed ridge-like process from the middle of the inner
surface of the shaft, and the deep and narrow fissure between the distal condyles.
This part of the femur had been figured and referred by Dr. Mantell to the Iguanodon,
in his ‘ Geology of the South-East of England,’ Nov. 1833, p. 310, pl. IV, figs. 3 and4;
and the subsequent discovery of the Maidstone specimen confirmed the accuracy of
that determination.

The bone which is figured in Pl. I, fig. 8 of the same work, as the tibia of the
Iguanodon, is also shown to be correctly so called by the Maidstone specimen,

T. XXXII and T. XXXIV.
The following are the dimensions of the principal and best-preserved bones in that

specimen :—
Dorsal Vertebre.
Inches. Lines.
Antero-posterior diameter of centrum : . : : . : 3 10
Vertical diameter of articular end . 5 : ; ‘ 3 5 5 4 0
_ Transverse diameter of ditto & 1
From the base of the neurapophysis to ‘ts foe part of that of the spinous
process . ‘ ; 5 3 0
From ditto ditto ee mat of ditto 4 0
Antero-posterior extent of neural platform 4 6
Caudal Vertebre.
Antero-posterior diameter of centrum 2 5
Vertical diameter of articular end 2 5
Transverse diameter of ditto 1 ll
From the base of the neurapophysis to the forecourt of that of Ate spinous
process . 5 : 6 : F
From _ ditto ditto back part of ditto : : . 1 6
Clavicle.
Length of the bone 37 0
Breadth across the process at the troadeh: end . 8 0
4 0

Breadth across the narrower end
15

114 FOSSIL REPTILIA OF THE

Scapula.
Inches. Lines.

Length of the bone 0 c : : ; 0 : 29 0
Breadth across the middle of fis shaft ; . F , ; 2 F 3 0

Humerus.
Length : ‘ i : A : 3 : y é : 19 0
Breadth of proximal ak 2 i 5 4 3 : : 5 6 0
Breadth of distalend . 3 5 4 9 5 - 5 t ‘ 4 0

Ulna.

Length 5 : 4 . : : é $ Fi 5 ‘ 18 0
Breadth of proximal al 3 : ‘ 5 , ; - 5 3 0
Ilium.

Length : 5 5 és A ; : 2 5 5 ex) 0
Breadth across the Srlnreed and - c : : : ; : 5 | Uo 0
Extent of sacro-iliae articulation . c 5 : : : : . 19 0
Femur.

Length : : : : : : é : : 5 : q 8B) 0
Tibia.

Length : : . . : : ; . - : : 0 31 0

The detached teeth and bones of the Iguanodon successively discovered in the
Wealden strata of Sussex, and afterwards found associated together to the extent of
nearly half the skeleton of one and the same individual in the Green-sand quarries of
Mr. Bensted, offer not the least marvellous or significant evidences of the inhabitants
of the now temperate latitudes during the later secondary periods of the formation of
the earth’s crust.

With vertebra subconcave at both articular extremities, having, in the dorsal
region, lofty and expanded neural arches, and doubly articulated ribs, and characterised
in the sacral region by their unusual number and complication of structure; with a
Lacertian pectoral arch, crocodilian proportions of the fore-limbs, and unusually
large bones of the hind limbs, excavated by large medullary cavities and adapted for
terrestrial progression, as well as for natation ;—the Zyvanodon was distinguished by

CRETACEOUS FORMATIONS. 115

teeth, resembling in shape those of the Iguana, but in structure differing from the
teeth of that and every other known reptile, and unequivocally indicating the former
existence in the Dinosaurian Order of a gigantic representative of the small group of
living lizards which subsist on vegetable substances.

The important difference which the fossil teeth presented in the form of their
grinding surface was pointed out by Cuvier,* of whose description Dr. Mantell adopted
a condensed view in his ‘ Illustrations of the Geology of Sussex,’ 4to, 1827, p. 72. The
combination of this dental distinction with the vertebral and costal characters, which
prove the Jguanodon not to have belonged to the same group of Saurians as that which
includes the Iguana and other modern lizards, rendered it highly desirable to ascertain
by the improved modes of investigating dental structure, the actual amount of corres-
pondence between the Jywanodon and Iguana in this respect. This I have done in my
general description of teeth of reptiles,t from which the following description is
abridged :—

The teeth of the Jyuwanodon, though resembling most closely those of the Iguana,
do not present an exact magnified image of them, but differ in the greater relative
thickness of the crown, its more complicated external surface, and, still more essen-
tially, in a modification of the internal structure, by which the Jywanodon equally
deviates from every other known reptile.

As in the Iguana, the base of the tooth is elongated and contracted ; the crown
expanded, and smoothly convex on the inner side ; when first formed it is acuminated,
compressed, its sloping sides serrated, and its external surface traversed by a median
longitudinal ridge, and coated by a layer of enamel, but beyond this point the descrip-
tion of the tooth of the /ywanodon indicates characters peculiar to that genus. In
most of the teeth that have hitherto been found, three longitudinal ridges traverse the
outer surface of the crown, one on each side of the median primitive ridge; these are
separated from each other, and from the serrated margins of the crown by four wide
and smooth longitudinal grooves. The relative width of these grooves varies in
different teeth ; sometimes a fourth small longitudinal ridge is developed on the outer
side of the crown. The marginal serrations, which at first sight appear to be simple
notches, as in the Iguana, present under a low magnifying power the form of trans-
verse ridges, themselves notched, so as to resemble the mammillated margins of the
unworn plates of the elephant’s grinder: slight grooves lead from the interspaces of
these notches upon the sides of the marginal ridges. These ridges or dentations do
not extend beyond the expanded part of the crown: the longitudinal ridges are
continued further down, especially the median ones, which do not subside till the fang
of the tooth begins to assume its subcylindrical form. The tooth at first increases
both in breadth and thickness; it then diminishes in breadth, but its thickness goes on

* Ossemens Fossiles, 1824, vol. v, part ii, p. 351.
+ Odontography, part ii, p. 249; and Transactions of the British Association, 1838.

116 FOSSIL REPTILIA OF THE

increasing ; in the larger and fully formed teeth, the fang decreases in every diameter,
and sometimes tapers almost to a point. The smooth unbroken surface of such fangs
indicates that they did not adhere to the inner side of the maxille, as in the Iguana,
but were placed in separate alveoli, as in the Crocodile and Megalosaur: such support
would appear, indeed, to be indispensable to teeth so worn by mastication as those of
the Jguanodon. ,

The apex of the tooth soon begins to be worn away ; and it would appear, by many
specimens that the teeth were retained until nearly the whole of the crown had yielded
to the daily abrasion. In these teeth, however, the deep excavation of the remaining
fang plainly bespeaks the progress of the successional tooth prepared to supply the
place of the worn out grinder. At the earlier stages of abrasion a sharp edge is
maintained at the external part of the tooth by means of the enamel which covers that
surface of the crown; the prominent ridges upon that surface give a smuous contour
to the middle of the cutting edge, whilst its sides are jagged by the lateral serrations :
the adaptation of this admirable dental instrument to the cropping and comminution
of such tough vegetable food as the Clathrarie and similar plants, which are found
buried with the /ywanodon, is pointed out by Dr. Buckland, with his usual felicity of
illustration, in his ‘ Bridgewater Treatise,’ vol. i, p. 246.

When the crown is worn away beyond the enamel, it presents a broad and nearly
horizontal grinding surface, and now another dental substance is brought into use to
give an inequality to that surface; this is the ossified remnant of the pulp, which,
being firmer than the surrounding dentine, forms a slight transverse ridge in the
middle of the grinding surface: the tooth in this stage has exchanged the functions
of an incisor for that of a molar, and is prepared to give the final compression, or
comminution, to the coarsely divided vegetable matters.

The marginal edge of the incisive condition of the tooth, and the median ridge of
the molar stage, are more effectually established by the introduction of a modification
into the texture of the dentine, by which it is rendered softer than in the existing
Iguanze and other reptiles, and more easily worn away: this is effected by an arrest of
the calcifying process along certain cylindrical tracts of the pulp, which is thus con-
tinued, in the form of medullary canals, analogous to those in the soft dentine of the
Megatherium’s grinder, from the central cavity, at pretty regular intervals, parallel
with the calcigerous tubes, nearly to the surface of the tooth. The medullary canals
radiate from the internal and lateral sides of the pulp cavity, and are confined to the
dentine forming the corresponding walls of the tooth: their diameter is ;2,,th of an
inch: they are separated by pretty regular intervals equal to from six to eight of their
own diameters; they sometimes divide once in their course. Each medullary canal is

surrounded by a clear space; its cavity was occupied in the section described by a
substance of a deeper yellow colour than the rest of the dentine.
The calcigerous tubes present a diameter of

L>ath of an inch, with interspaces

25>

CRETACEOUS FORMATIONS. 117

equal to about four of their diameters. At the first part of their course, near the pulp
cavity, they are bent in strong undulations, but afterwards proceed in slight and
regular primary curves, or in nearly straight lines to the periphery of the tooth.
When viewed in a longitudinal section of the tooth, the concavity of the primary
curvature is turned towards the base of the tooth: the lowest tubes are inclined
towards the Foot, the rest have a general direction at right angles to the axis of the
tooth ; the few calcigerous tubes, which proceed vertically to the apex, are soon worn
away, and can be seen only in a section of the apical part of the crown of an incom-
pletely developed tooth. The secondary undulations of each tooth are regular and
very minute. The branches, both primary and secondary, of the calcigerous tubes
are sent off from the concave side of the main inflections; the minute secondary
branches are remarkable at certain parts of the tooth for their flexuous ramifications,
anastomoses, and dilatations into minute calcigerous cells, which take place along
nearly parallel lines for a limited extent of the course of the main tubes. The appear-
ance of interruption in the course of the calcigerous tubes, occasioned by this
modification of their secondary branches, is represented by the irregularly-dotted
tracts in the figure. This modification must contribute, with the medullary canals,
though in a minor degree, in producing that inequality of texture and of density in
the dentine, which renders the broad and thick tooth of the Jgwanodon more efficient
as a triturating instrument.

The enamel which invests the harder dentine, forming the outer side of the tooth,
presents the same peculiar dirty brown colour, when viewed by transmitted light, as
in most other teeth: very minute and scarcely perceptible undulating fibres, running
vertically to the surface of the tooth, form the only structure I have been able to
detect in it.

The remains of the pulp in the contracted cavity of the completely-formed tooth,
are converted into a dense but true osseous substance, characterised by minute elliptical
radiated cells, whose long axis is parallel with the plane of the concentric lamelle,
which surround the few and contracted medullary canals in this substance.

The microscopical examination of the structure of the Iguanodon’s teeth thus
contributes additional evidence of the perfection of their adaptation to the offices to
which their more obvious characters had indicated them to have been destined.

To preserve a trenchant edge, a partial coating of enamel is applied; and, that the
thick body of the tooth might be worn away in a more regularly oblique plane, the
dentine is rendered softer as it recedes from the enameled edge by the simple con-
trivance of arresting the calcifying process along certain tracts of the inner wall of the
tooth. When attrition has at length exhausted the enamel, and the tooth is limited
to its function as a grinder, a third substance has been prepared in the ossified remnant
of the pulp to add to the efficiency of the dental instrument in its final capacity. And
if the following reflections were natural and just after a review of the external characters

118 FOSSIL REPTILIA.

of the dental organs of the Zguanodon, their truth and beauty become still more manifest
as our knowledge of their subject becomes more particular and exact.

“Tn this curious piece of animal mechanism we find a varied adjustment of all parts
and proportions of the tooth, to the exercise of peculiar functions, attended by com-
pensations adapted to shifting conditions of the instrument, during different stages of
its consumption. And we must estimate the works of nature by a different standard
from that which we apply to the productions of human art, if we can view such
examples of mechanical contrivance, united with so much economy of expenditure, and
with such anticipated adaptations to varying conditions in their application, without
feeling a profound conviction that all this adjustment has resulted from design and
high intelligence.”-—(‘ Buckland’s Bridgewater Treatise,’ vol. i, p. 249.)

Cc, AND J. ADLARD, PRINTERS, BARTHOLOMEW CLOSE.

i

a

TAB. I.

Chelone Benstedi, nat. size.
Fig.

1. Upper view of the carapace.

2. Side view of the carapace.

The letters and figures are explained in the text.

From the Middle Chalk, Kent. In the Museum of Dr. Mantell, F.R.S.

Bee ais

Chelone Benstédt

op pepe 7
05 Linkel del. el

TAB. II.

Chelone Benstedi, nat. size.

Fig.
1. Under view of the carapace.

2. Upper view, with the part of the carapace removed to show the bones of the

plastron and coracoid.

From the Middle Chalk, Kent. In the Museum of Dr. Mantell, F.R.S.

DANKE:

Ate.ct MEP

it
UA Pe

Chelone Benslede .

hh

RATER EAR RESO

“regs papsouooeme ;

i
}
|
t

ye alee eH ide fae

an

Hoye GMI TMP Se

- apis : ae ae . rile citi 7
“spre Rand wo 2 FE gi: 7
day ba oe

ot A

us

TAB. III.

Chelone Benstedi, nat. size.

Fig.

fo)
1. Upper view of the carapace.

bo

. Side view of the carapace.
3. Oblique view of fore-part and left side of the carapace.

4. Outline of transverse section of the carapace.

From the Middle Chalk, Kent. In the Museum of J. S. Bowerbank, Esq., F.R.S.

Yip nit mdO mg me mr | m6

aes

Gar 7 .
Jos. Linkel, del ct lth, Chelone benslede ‘ > Tha

TAB. IV.

Fig.
1—10, 13—16. Teeth of Ichthyosaurus campylodon.

From the Chalk and Green-sand of Cambridgeshire. In the Collection of
James Carter, Esq., of Cambridge.

11. Back tooth of a recent Alligator, showing the circular hole made by the ab-
sorption consequent on the pressure of a young tooth.

2. Tooth of a recent Crocodile, showing the young tooth, that has penetrated the
pulp-cavity of the old tooth.

17. Tooth of Ichthyosaurus communis, from the Lias of Lyme Regis.

All the figures are of the natural size.

ETE IE

See kc

x 5
«
.
? =
+ 5
.
.
+
~-

TAB. V.

Chelone Campert, nat. size.

Fig.
1. External surface of two dermal plates, probably

ce

marginal’ ones.

2. Transverse section of one of the above, and of a subjacent inverted plate.

From the Upper Chalk of Kent. In the Museum of Thomas Charles, Esq.,
of Maidstone.

Chelone Campert.

EromNakarenn Stone ty J Bralehen.

Day & Sen; Ba 0 the Puce

TAB. VI.

Chelone Camperi (*), nat. size.

Fig.
1. Outer surface of a series of five “ marginal” plates.

2. Inside view of the same.

3. Portions of two ribs of the carapace of apparently the same species of Turtle.

From the Middle Chalk of Kent. In the Museum of Mrs. Smith, of Tonbridge Wells.

TAB. VIL.
Protemys serrata, half nat. size.
Upper surface of the carapace.

The letters and figures signify the same parts as in the preceding Monograph.

From the “ Kentish Rag,” Green-sand Formation, Maidstone. In the Col-
lection of Capt. Guise, F.G.S.

T. VI.

SI Linked del, eb titty, Day iSor, tethPta the Queen

Fig.
. Upper view of the skull of Chelone pulchriceps, nat. size.

ON Das

10.

TAB. VII 2.

Side view of ditto ditto.
Under view of ditto ditto.

7. Parietal.
8. Mastoid.
1. Frontal.
12. Post-frontal.
14. Pre-frontal.
15. Nasal.
20. Palatine.
21. Maxillary.
22. Premaxillary.
24. Pterygoid.
From the Green-sand, Barnwell, Cambridgeshire. In the Collection of the
Rev. Thomas Image, M.A., of Whepstead.

. Upper view of the mandible of a Chelonian.

. Side view of the same mandible, nat. size.

Under view of the mandible of another species of Chelonian.

. Side view of the same mandible, nat. size.

. A marginal plate of the carapace of a Turtle (Chelone).

The above three specimens are from the Chalk of Kent: and are in the
collection of James Scott Bowerbank, Esq., F.R.S.

. The scapula 51, and coracoid 52, of a Turtle (Chelone).

From the Chalk of Sussex. In the Collection of Henry Catt, Esq., of Brighton.
Part of the coracoid of a Turtle (Che/one).
From the Burham Chalk-pit, Kent. In the Collection of Mrs. Smith, of
Tonbridge Wells.

. The upper or inner surface of the left hyosternal bone of Protemys serrata,

nat. size. From the same specimen as the subject of T. VII.

. The left hyosternal bone of an immature Hmys, similarly mutilated of its inner

process.

.. VILA.

ay

L del. lath.

J.

aera %

7 Aigants Pe wal

A | hi
Hos

tala

sees iy

7

HG RGM ABORT RE

re)

ss

Fig.
. Side view of a hinder dorsal vertebra.

. Back view of ditto.

TAB. VIII.

Mosasaurus gracilis, nat. size.

Two caudal vertebre.

From the Upper Chalk, near Lewes. In the Mantellian Collection, British
Museum.

Mosasaurus Hoffmannc.

. Side view of a hinder dorsal vertebra, mat. size.

5. Back view of ditto.

From the Cretaceous Beds, at Maestricht. In the British Museum.

. The half of a vertically and longitudinally bisected vertebral centrum of a

Mosasaurus gracilis, which was partially enclosed in a nodule of flint, from
the Upper Chalk, at Kemptown, Brighton. The siliceous matter has
infiltrated itself into much of the cellular structure of the middle part of the
centrum. The densest part of the cellular structure is near the concave
surface of the vertebra.

In the Collection of Dr. Mantell, F.R.S., by whose obliging permission it is
figured for the present Monograph.

T. VI.

Acie ON

‘- Wade ; *
’ Walt iss EV ayes %

l4a.

15a.

TAB. IX.

Part of the lower jaw of Mosasaurus gracilis, nat. size.

. Part of the upper jaw of ditto.

Body of a lumbar vertebra of ditto.
Body of a dorsal vertebra of ditto.
Anterior concave surface of the same vertebra.

Anterior view of a mutilated caudal vertebra, showing the much expanded
heemal arch e.
From the Upper Chalk, at Offham-pit, Sussex. In the Collection of Henry
Catt, Esq., of Brighton.
Under view of the body of a cervical vertebra of Plesiosaurus constrictus.
End view of the same vertebra. 7
From the Steyning Chalk-pit, Sussex.
Tooth of a Plesiosaurus.
From the Scaddlescombe Chalk-pit, near Lewes, Sussex.

Tooth of a Plestosaurus.

From the Southeram Chalk-pit, Sussex.
Tooth of a Plestosaurus.

From the Southeram Chalk-pit, Sussex.
Tooth of Polyptychodon interruptus.
Base of the same tooth.

From the Chalk, near Valmer, Lewes.
Nine dorsal vertebree of a Lizard (Coniosaurus crassidens).
Part of the lower jaw and some attached vertebree of Contosaurus crassidens.
A magnified tooth of ditto.
View of part of the alveolar groove and teeth of ditto.
A magnified hinder tooth of ditto.

From the Lower Chalk at Clayton, Sussex. In the Collection of Henry Catt,
Esq., of Brighton.

All the figures are of the natural size.

, LU a
i

eget! . :

> 4
t s
.
.
S

>

t i

on
i i i : My

—

= a
ah a3

23

ab PPuty any

Leet ORG is

a

da"

A.
5

5**, Outline of the transverse section near the base of the same tooth.

“I
.

i?)

TAB. IX 4.
Leiodon anceps, nat. size.

Part of the lower jaw with teeth.

Diagrammatic section of a tooth, showing the pulp-cavity, which contained a
siliceous mass, fig. 2’.
(Copied from the figures in the ‘ London Geological Journal,’ 1846, Pls. iv and vi.)

A portion of the same or a similar jaw, with the crowns of the teeth broken
away.

Upper or alveolar surface of the same portion of jaw.
The crown of one of the teeth from the same portion of jaw.

The base of the same tooth.

The above specimens are from the Chalk of Norfolk, or to the North of the
Thames ; and are in the Collection of Edward Charlesworth, Esq., of York.

The crown of a tooth of Lezodon anceps.
From the Chalk of Sussex. In the Collection of Henry Catt, Esq., of Brighton.

Outline of the transverse section of a tooth of Mosasaurus Hoffmanni.
Outline of the transverse section of the tooth of MWosasaurus Maximiliani.

Outline of the transverse section of the tooth of Mosasaurus gracilis.

ane
i

J,

i say od
et
4) es

gl _

TAB. X.

1. Mutilated head and vertebra of the fore-part of the trunk of Dolichosaurus

i)

wm OO

“I

(os)

longicolhs.

. Outline of part of the lower jaw.
. The same, magnified.
. Vertebree of the hind part of the trunk and pelvis of Dolichosaurus longicollis.

From the Middle Chalk, Kent. Fig. 1, in the Collection of Mrs. Smith, of
Tonbridge Wells. Fig. 2, in that of Sir Philip de Malpas Grey Egerton,
Bart.e HRs eb:

. Portion of the lower jaw of Raphiosaurus subulidens.

6.

Upper or alveolar surface of ditto.
From the Lower Chalk of Cambridgeshire. In the Collection of James Carter,
Esq., of Cambridge.

. Portion of the lower jaw, with a tooth in situ, of Polyptychodon interruptus.

From the Chalk of Kent. In the Collection of Mrs. Smith, of Tonbridge Wells.

. Crown of the tooth of Polyptychodon interruptus.

9. Crown of the tooth of ditto.

From the Green-sand of Cambridgeshire. In the Collection of James Carter, Esq.

All the figures, save fig. 3, are of the natural size.

VAUUTE

S

ee an

TAB. XI.
Fig.
1—7. Teeth of Polyptychodon interruptus, nat. size.

From the Lower Chalk, near Lewes, Sussex. In the Museum of Mr. Potter,

of Lewes.

8. Tooth of Polyptychodon continuus (?), nat. size.

From the Lower Chalk of Sussex. In the Museum of Henry Catt, Esq., of

Brighton.

1 fi). bp

“tychodon.

vp

e

OC

pe apaL ues

‘leben

Natur e-on Stone by J. Erx

TOMA

F

TAB. XII.

Polyptychodon continuus (*).

. Lower end of shaft of femur, (scale of 2 inches to 1 foot.)

. Lower end of shaft of humerus, (scale of 2 inches to 1 foot.)

. A larger portion of the shaft of a long bone, (scale of 2 inches to | foot.)
. A fragment of a long bone, near the proximal end of humerus?

. Portions of the pubis, Pp, and ischium, 1, (scale of 2 inches to 1 foot.)

. Fractured portion of the ilium, (scale of 4 inches to a foot.)

From the Green-sand, near Hythe. Discovered and presented by H. Mackeson,
Esq., of Hythe. Kent, to the British Museum.

Xf.

7

ie
Lert

AG

Bx

J Firalehen, del. et lily.

TAB. XIII.

Polyptychodon continuus (*).

Fig.
1. A block of Green-sand stone, containing the shaft of a tibia, T, and the lower end
of that of a fibula, F, (scale of 2 inches to a foot.)

2. A block of Green-sand stone, containing the shaft of the humerus, H, and that of
the ulna, u, (same scale.)

3. A portion of the matrix, with impressions of the shafts of two metacarpal or
metatarsal bones (same scale.)
4 and 5. Fragments of long bones (same scale.)

From the Green-sand, near Hythe, Kent. Discovered and presented by
H. Mackeson, Esq., to the British Museum.

Ll. Xie

ec Lith

Led.

TIHlEber ¢

Ly

ep

Polaninchodon (2)

Ary vetd |

ee

ie sve 7 a.
i SAT ED

TAB. XIV.

1 and 2. Crown of the tooth of Polyptychodon interruptus.

3. Outline of the base of the same tooth.
From the Chalk of Sussex.

sa

Crown of the tooth of Polyptychodon continuus.

From the Chalk of Kent. In the Collection of H. W. Taylor, Esq., of Brixton
Hill.

On

. Crown of the tooth of Polyptychodon continuus.

6. Longitudinal section of the same tooth.

From the Kentish Rag, Green-sand Formation, near Maidstone. In the
Collection of J. Bensted, Esq.

All the figures are of the natural size.

TT XIV

Se APSE

ne by J forxdeben

ot,

Mi,

TAB. XV.
A slab of Green-sand, with portions of the skeleton of a young Crocodile.

From near Hastings. In the Collection of W. D. Saull, Esq., F.G.S.

Figs. 1 and 2. Portions of the jaws of the same Crocodile, nat. size.

=

Le Nie

rileben

Ei;

]

rom Nuture

ke

Tustone by J

TAB. XVI.

A portion of the lower jaw of Polyptychodon.

From the Chalk of Kent. In the Collection of J. Toulmin Smith, Esq., of

Highgate. Nat. size.

TE XV

JS Erxcleben del, eé lith,

TAB. XVII.

Portion of the paddle of a large Plesiosaurus, nat. size.

From the Chalk of Kent. In the Collection of Mrs. Smith, of Tonbridge Wells.

TAB. XVIII.

Cervical Vertebra of Plesiosaurus Bernardi, nat. size.

Fig.
. Front view.

—

2. Back view of spinous process.
3. Side view.
4. Under view.

From the Upper Chalk of Sussex. In the Collection of the late Fred. Dixon, Esq.,
F.G.8., of Worthing.

Lith trom Nature by Scharf

TAB. XIX.

Cervical vertebra of another species of P/esvosaurus.

From the Chalk of Kent. In the Collection of Mrs. Smith, of Tonbridge Wells.

T_XIX

Z,

MLOVEH .

LT

f° Jy.

tone by.

oe
7b)

alure On

ne
tLN

From

TAB. XX.

Plesiosaurus pachyomus, nat. size.

. Side view of centrum of cervical vertebra.

Front view of ditto.

Side of centrum of a more posterior cervical vertebra.

Front view of ditto.

Side view of centrum of penultimate cervical vertebra.

. Front view of ditto.

From the Green-sand, near Cambridge. In the Collection of James Carter,
Esq., M.R.C.S.

Three views of part of a tooth of a Plesiosaurus.

. Portion of a similar tooth.

From the Green-sand, near Shanklin, Isle of Wight.

RS

Se
Se

TAB. XXI.

Plesiosaurus pachyomus, nat. size.

Fig.
. Side view of centrum of dorsal vertebra.

—

. Under view of ditto.
. Upper view of ditto.

. Upper view of the centrum of a smaller dorsal vertebra.

Sx ES 69 WS

. A section through the centrum of a small dorsal vertebra, showing the course of

the vertical venous canals.
6. Under view of a caudal vertebra.

From the Green-sand, near Cambridge. In the Collection of James Carter,
Esq., M.R.C.S.

0,0),

T

TAB. XXII.

Ichthyosaurus campylodon, nat. size.
Fig.
1. Side view of the body or centrum of a vertebra of the trunk.
2. Front view of ditto.
3. Section of a similar vertebra, showing the form and depth of the opposite
articular surfaces.

From the Grey-chalk of the Round-down Tunnel, near Dover. In the Col-
lection of H. W. Taylor, Esq., of Brixton Hill.

LXXTT

“leben, del 2 lth

eM
ions

x
Ha

rid
ots
ee
a,
De
ss

ts
; Seine

TAB. XXIII.
Ichthyosaurus campylodon, nat. size.

Outer side of the dentary bone of the lower jaw.
Form of the section of the fractured end.

Inner side of a portion of the right ramus of the same lower jaw, formed by the
dentary piece, 32, with the terminations of the splenial pieces, 31.

Form of the section of the hinder fractured end.

**. Form of the section of the fore-part of the same portion.

Fragment of a portion of the right premandibular bone.

One of the teeth, from the base of which part of the thick cement has been
removed.
From the Grey-chalk of the Round-down Tunnel, near Dover. In the
Collection of H. W. Taylor, Esq., of Brixton Hill.

T. XX,

ae
BANG

Betas
<

Day Eden Lt th to The Cue

i

ae

T. XXM,

1 Erxteben del eh lith

Day &Son 1th" to The Jucen.

F’

TAB. XXIV.
Pterodactylus compressirostris, nat. size.

1. The lower or distal half of the humerus, with a portion of the radius or ulna.
2. One end of a long bone of the wing of the same Pterodactyle.
3. Part of the shaft of the radius or ulna, from the same block of Chalk, as fig. 1.

From the Chalk of Kent. In the Collection of Thomas Charles, Esq., of Maidstone.

TAB. XXV.

Ichthyosaurus campylodon, nat. size.
Fig.
1. Side view of a portion of the skull.
2. Upper view of the hinder half of the same portion of skull, showing the extremity
of the nasal bones, 15, dipping under the premaxillaries, 22.

From the Lower Chalk, near Cambridge. In the Collection of James Carter,
Esq., M.R.C.S.

7 XXV.

—

ats

T XXV.

Hrom: Nature on Stone by] Erecleben

TAB. XXVI.

Ichthyosaurus campylodon, nat. size.
Fig.
1. Section of the skull anterior to the maxillary bones.
15. Nasal bones.
22. Premaxillaries: g, external groove; ai, origin €f the internal alveolar
plate; ai’, where it appears to have been broken: ai’, thickened

terminal border of the plate ; a, external alveolar wall.
31. Splenial part of lower jaw.
32. Dentary part of ditto: g/, external groove; a/*, internal alveolar wall.

2. Section of the skull near the termination of the nasal bones 15, 15. o, vascular
canal: the other letters and figures as in the foregoing figure.
From the lower Chalk of Cambridgeshire. In the Collection of James Carter,
Esq., M.R.C.S.

S
\
N

TE;

one OY

St

on Nature on

Fr

TAB. XXVII.

Fig.
. Skull of Pterodactylus longirostris (after COLLINT).

—

. Left side of the skull of Pterodactylus crassirostris.

2

3. Right side of the same skull.

4. Restoration of the same skull (after GOLDFUss).
5

. Restoration of the skull of Pterodactylus compressirostris.

The tinted portions of fig. 5 are from the Middle Chalk of Kent, and are in the
Museum of James Scott Bowerbank, Esq., F.R.S.

TEX KV Te

SUA VN

RS riaqeee ee

z ya fo te
— = = Sy err we Re;
— = aA oe
eee Sa

ST tne ee

22

Day L Son, Luh to The Queen

T. XXVIII.

J Dakel With

Day Son, Ltth'to The Queen

ae iy : : i - a a ye = 4 |
by arg Hy 7) ge | Oe
“ae ( & : ; ee =

ane»

Gracia e
Sues , ;

10.

TAB. XXVIII.

Side view of the end of the upper jaw of Pterodactylus Cuvieri, nat. size ;
a, a, the alveoli.

Outline of the section at the hinder fractured part.

Anterior end of the jaw.

Palatal surface of the jaw.

The crown of one of the teeth of the same jaw.

The crown of another tooth of the same jaw.

Magnified view of a portion of the crown of a tooth of the same jaw.

Left side of two portions of the upper jaw of Pterodactylus compressirostris, nat.
size; a, a, alveoli.

Right side of the same two portions of jaw.

. Transverse section of the jaw at the fore part of the hinder fragment.

Palatal surface of the same two portions of jaw; p, the naso-palatine aperture.
Both the foregoing specimens are from the Burham Chalk-pit, Kent; and-are
in the Cabinet of James S. Bowerbank, Esq., F.R.S.

aL

* THAXX 1.

TAB. XXIX.

CHELONIAN FossILs, nat. size.

. Part of the plastron of a Turtle: the episternum, es, resting upon the left hyosternal.
. Part of a rib of a carapace.

1
2
3. Part of a larger rib of the carapace.
4. Part of a rib of a carapace.
. The hyosternal element of the plastron of a Chelone Benstedi.
. Portion of the scapula and clavicle of a Turtle.

5
6
7. One of the marginal plates of the carapace.
8. A humerus of a Turtle.

9)

. An ulna of a Turtle.

From the Chalk of Kent. In the Museum of Thomas Charles, Esq., of Maidstone.

XXX

i

Svein sercinteea

Pa Temraemse

Se

ree

SLEEP

zak naemerata so

=a

a ae
AAR

ocean
ee

a,

NWesccoy,

A
v

TromNaiure onStone by J. Ereleben,

TAB. XXX.

Fig.
1 and 2. Wing-bone of Plerodactylus Cuvieri.

2*. Articular end of ditto: @ and 4, articular surfaces; c, fractured surface leading
to the cavity of the bone.

3. Portion of the narrowest side of the same bone, showing the pneumatic foramen
at p.
, 3°. Section of the same bone four inches from the articular end, showing the thick-
ness of its dense osseous wall, and the wide air-cavity.
From the Burham Chalk-pit, Kent. In the Collection of J. Toulmin Smith, Esq.
4. A similar portion of a corresponding wing-bone of Pferodactylus compressirostris,
nat. size: y, the pneumatic foramen.
4*. Part of the articular extremity.
4**, Transverse section of the smallest part of the shaft.
From the Burham Chalk-pit, Kent. In the Collection of Jas. 8S. Bowerbank,
Esq., F.R.S.
5. Portions of the shafts of the radius and ulna of Pterodactylus compressirostris,
nat. size.
5.* The somewhat crushed and mutilated articular ends.
From the Burham Chalk-pit, Kent. In the Cabinet of Mrs. Smith, of
Tonbridge Wells.

J Dinkel, del. ek lth Day b Son, lan thelucen

oF Dinkel, dal eb tith

Digy Ser ith Pte the Oc

10.

Mls
12

me

13.
14.

es)
CON A et WD SG

TAB. XXXI.

Pterodactylus giganteus, Bowerbank ; nat. size.

. Right side of the anterior end of both jaws.

. Left side of ditto showing the beginning of the external nostril, 7.

Front view of both jaws, which are a little distorted.

Upper surface of the upper jaw.

. Under surface of the lower jaw.

. A tooth, magnified.

. Coalesced ends of scapula, 51, and coracoid, 52, showing the glenoid cavity, 9.
. Side view of ditto. @, acromion.

. A fragment of bone in the same block of chalk with the scapular arch, probably

a piece of the sternum.
Mutilated end of a long bone.
The great part of the shaft of a long bone of the wing.
Proximal portion of the shaft of probably the tibia.
Two portions of long bones, and a portion of a rib.

A fragment of a long bone.

All the above parts are from the Burham Chalk-pit, Kent, with the exception
of figs. 10 and 11, which are from the Halling Chalk-pit, in the same
county. In the Museum of James S. Bowerbank, Esq., F.R.S.

=
>

to
:
L
nA

—

Fig.
. Section of the ulna of a Pelican (Pelecanus onocrotalus), recent.

me ow

“NI

go

TAB. XXXIL.

. Proximal end of one of the bones of the wing-finger of the Pterodactylus

compressirostris.

. Portion of the shaft, probably of the femur of a large Pterodactyle ?

’. Form of the transverse section of ditto.

Three views of the distal trochlear joint of one of the long bones, probably
the metacarpal of the wing-finger, of a large Pterodactyle ?

. Two views of a similar, but less mutilated bone.

From the Middle Chalk of Kent.

6’. Two views of a fragment of one of the long bones of a large Pterodactyle.

. A portion of the shaft of a long bone of a large Pterodactyle.

8’, 8”. Three views of a portion of a humerus of a smaller Pterodactyle.

From the lower Green-sand, near Cambridge.

All the figures are of the natural size.

VT. XXXIT

Penney
ST a ad

TAB. XXXIII.
Iquanodon Mantelli, scale of 2 inches to a foot.

A considerable portion of the skeleton in a block of the Kentish Rag variety of

the Green-sand Stone Formation.

Discovered by Mr. Bensted, of Maidstone. In the Collection of the British Museum.

T XX

Sec tre tea

SER est
Be eres

irtcel, aA

=

! Dinkeb, del 2 lth

TAB. XXXIV.

Outline of the same specimen, with the names inscribed on the best preserved _

bones: in the vertebrze, d, is “ dorsal,” and c, “ caudal.”

LT XXXTY.

Dinkle del. ath Day ESon, Lin’ 't The Queen

TNXAX TY.

Day bSen Leth" te The Queen.

TAB. XXXV.

Iguanodon Mantelli, nat. size.

2»
Side view of a dorsal vertebra.
p- Parapophysis, or lower transverse process, with the surface for the head
of the rib.
d. Fractured base of diapophysis or upper transverse process.

n,n. Base of neurapophysis.
n*, nl’. Neural platform.
z. Posterior zygapophysis.

ns. Neural spine.

From the Kentish Rag. In the Collection of the British Museum.

Ye

HEI

-.

TAB. XXXVI.
Tguanodon Mantelli, nat. size.

Front view of a dorsal vertebra.
Base of neurapophysis.

:, 2. Anterior zygapophyses.
d. Base of diapophysis.

From the Kentish Rag. In the Collection of the British Museum.

S
=
s
N

TAB. XXXVII.

Iguanodon Mantellt, nat. size.
Fig.
1. Front view of a caudal vertebra.
2. Side view of ditto.
3. Under view of ditto.

4. Under view of another caudal vertebra.

From the Kentish Rag, near Maidstone. In the Collection of the British Museum.

T. XXXVI.

MONOGRAPH

ON

THE YOSSI) WEPITILIA

OF THE

CRETACEOUS FORMATIONS.

SUPPLEMENT No. I.

Paces 1—19; Pratas I—IV.

PTEROSAURIA (Preropactytts).

BY

PROFESSOR OWEN, D.C.L, F.RS, FLS, F.GS., &.
Issued in the Volume for the Year 1857.

LONDON:
PRINTED FOR THE PALZONTOGRAPHICAL SOCIETY.
1859.

SUPPLEMENT (No. I)

MONOGRAPH

ON

Eee EOFS iS elit EVR EW pea

OF

THE CRETACEOUS FORMATIONS.

Orper—PTEROSAURIA, Owen.
Genus—PreropactyLus, Cuvier.

In the ‘ Monograph of the Fossil Reptilia of the Chalk Formations,’ p. 103,*
the occurrence of remains of a large Pterodactyle in the Green-sand formation near
Cambridge, was noticed, and portions of the wing-bones were figured in Tab. XXXII,
figs. 6—8.f

The Woodwardian Museum of the University of Cambridge has subsequently
been enriched by successive acquisitions of fossils, obtained, chiefly through the exer-
tions of Lucas Barrett, Esq., F.G.S., from the same stratum of ‘ Upper Green-
sand,’ near Cambridge, where I had: the opportunity of inspecting them last year.
All those belonging to the Pterosauria have since been liberally transmitted to me by
my friend Prorgessor Sepewick for description and illustration in the Monographs of
the Palzontographical Society,-and I have subsequently received a few highly interest-
ing additional examples of Pterodactyle remains from sources which will be duly
acknowledged in the sequel.

* Volume of the Paleontographical Society, 4to, 1851. + Ib.
1

2 FOSSIL REPTILIA OF THE

PreropactyLus Sepewicki1, Owen. Jaws and teeth, Tabs. I and III.

The specimen (Tab. I, fig. 1, a, 6, c, d) is the fore part of the upper jaw, contain-
ing the first seven sockets of the teeth, in a few of the anterior of which the base of
the tooth is retained. The first two sockets open upon the obtuse extremity of the
jaw (fig. 1, c), and have a direction showing that their teeth projected obliquely
forward, so as to prolong the prehensile reach of the jaw; the second and third
sockets are the largest, and cause a slight transverse swelling (fig. 1,6); the fourth is
suddenly smaller, and the three following retain nearly the same size, or show a slight
increase as they pass backward. The apertures of the sockets are elliptic, with the
long axis extending obliquely from before outward and backward, not parallel with
the axis of the jaw; the plane of the outlet inclines slightly outward (fig. 1, c). The
interval between two sockets is about half the long diameter of each. On one side
of the figured specimen the fifth socket is obliterated. The anterior termination of
the jaw is obtuse; the sides are smooth, flat, converging at an acute angle to what
almost forms a ridge above (fig. 1, c, d) ; the jaw gradually increases in vertical diameter
as it proceeds backward, the upper contour being straight as far as it can be traced
in the fossil. The palatal surface is entire, narrowest between the second sockets,
suddenly broader and flat between the third pair, retaining about the same breadth,
but with a slight convexity and feeble indication of a median ridge in the rest of its
extent, the ridge not being so strongly marked as it appears in fig. 1, b.

The Pterosaurian nature of this fossil is shown by the extreme thinness of the
compact bony wall of the jaw; its relation to the genus Pterodactylus, as contra-
distinguished from the Rhamphorhynchus, V. Meyer, is proved by the terminal posi-
tion of the sockets; and sufficient of the outer side wall of the jaw is preserved to
show that the nostril did not advance so far forward as in Dimorphodon—the generic
form of Pterodactyle from the Lower Lias. i

By its size and true or proper Pterodactyle affinities the present specimen most
resembles Pterodactylus Cuviert of the Chalk, (Monog. cit., Tab. XXVIID ; but it
offers the following well-marked differences: a greater proportional size of the
anterior sockets, with a corresponding expansion of the fore part of the jaw; a
greater number and closer arrangement of the sockets; a greater depth of the jaw,
in proportion to the breadth of the palate. The extent of the jaw, e. g., containing the
first seven sockets, in Pterodactylus Sedqwickii, is 2 inches 9 lines ; but in Pterodactylus
Cuvieri it is 3 inches 6 lines: the depth of the jaw, above the third socket, in Péter.
Sedgwickii, is 14 lines ; in Péter. Cuvieri it is 8 lines ; whilst the breadth of the palate
between the third pair of sockets is only 1 line less in Pter. Cuvieri than in Pter.
Sedgwickii. It needs only to compare the fore part of the jaw of the Great Chalk

CRETACEOUS FORMATIONS, 3

Pterodactyle (Monog. cit., Tab. XXVIII, figs. 1—4) with the same part of the still
larger species from the Green-sand (Tab. I, figs. 1 and 2), to be convinced of their
specific distinction.

The difference is still more marked between Pterodactylus Sedgwickti and Ptero-
dactylus compressirostris (Tab. XXVIII, figs.8, 9,10). The rapid increase of depth
as the jaw extends backward,in Pter. giganteus, Bk. (ib., Tab. XX XI, fig. 1), shows that
that comparatively small species cannot be the young of the present truly gigantic
Pterodactyle of the Upper Green-sand. I have no hesitation, therefore, in basing
on the above-described fossil a new species, at present the largest known in the order
of Flying Saurians, which I propose to dedicate to the Woodwardian Professor of
Geology in the University of Cambridge, who for forty years has discharged the
duties of that office with exemplary zeal and a rare eloquence, has almest created the
museum still called (Woodwardian,) and has enriched geological science by original
researches which have thrown light on its most obscure and difficult problems.

The next fossil selected from the Pterosaurian series of Green-sand fossils for
present description is the fore part of the jaw figured in Tab. I, figs. 2, a, b, ¢, d.
This contains about the same number of sockets in the same extent of jaw as in fig. 1;
and the last four sockets present about the same extent of interspace, with the same
diminution of size, as compared with the two preceding sockets. But the walls of
these sockets form no lateral expansion, the depth of the jaw is less, and the flat sides
converge to a sharper ridge, fig. c; the aspect of the sockets is also more obliquely out-
ward, the interspace between the pairs is narrower, and this is traversed by a median
groove 4th of an inch across, fig. b. Were this specimen a part of an upper jaw, it would
indicate a distinct species from Pterodactylus Sedgwickii, as exemplified by fig. 1;
but I regard fig. 2 as being the fore part of a lower jaw, and consequently as most pro-
bably belonging to the same species. The minor depth of the bone accords with the
proportions of the lower jaw in Pter. giganteus (Monog. cit., Tab. XXXI, figs. 1 and
2); and the sockets are directed more obliquely outward, as they likewise are in the
lower jaw of Pter. giganteus, as compared with the upper one of the specimen of that
species, in which both jaws of the same head have been preserved. Jn the belief, there-
fore, that fig. 2, a, b, represents part of the under jaw of Pterodactylus Sedqwickii, the
median groove on the upper or oral surface of the prolonged ‘symphysis mandibule’ (fig.
2, b) suggests that it may have served to lodge a long filiform tongue, perhaps
bifurcate at the end, as in the Leptoglossal Lizards of the present day. The same thin
outer wall, and capacious cavity filled by matrix, and probably in the living reptile by
air, characterise the lower (fig. 2, c), as they do the upper, jaws of Pterodactylus
Sedgwick. In one of the sockets of the lower jaw part of the hollow base of an old
tooth is preserved, with the sharp slender point of a new tooth projecting from the
inner side of the socket (Tab. I, fig. 2, d), showing the same relative position of the
matrix of the successional tooth, as may be observed in the existing Crocodile.

4 FOSSIL REPTILIA OF THE

PreroDAcTYLus Firront, Owen. Jaws and teeth, Tab. I, figs. 3, 4, 5.

Figure 3, a, b, &c., shows the fore part of the upper jaw of a Pterodactyle, with the
first and second pairs of alveoli. In the minor depth of the jaw, compared with its
basal breadth, in its more obtusely rounded upper surface, and in the greater extent
of space between the alveoli of the same size, this maxillary fragment indicates a very
distinct species from the Pterodactylus Sedgwicki, but one probably not much inferior
in size. I propose to dedicate it to my friend, Dr. Fitton, F.R.S., one of the founders
of the Geological Society of London, and who may be regarded as the discoverer of
the system now called ‘‘ Neocomian,” which includes the Green-sand matrix of the
Flying Reptiles under consideration. The sockets in the fragment (fig. 3) may —
answer to the second and third in fig. 1, though there scarcely seems room for a pair
in advance of the foremost in the specimen figured ; be that as it may, the distance
between the first and second socket in the specimen of Pterodactylus Fittoni is,
relatively to the size of the socket, greater than the interval between the second and
third sockets in Pterodactylus Sedgwickii, and much greater than that between the
second and third sockets. The outer wall of the largest anterior socket in Pter.
Fitton is much less prominent than in Pter. Sedgwickii, and the lateral expansion of
the fore part of the upper jaw must have been relatively less ; the form of the bony
palate is different, there being a distinct though shallow longitudinal groove on each
side a low obtuse median ridge. The diastema between the second and third tooth is
shown to exceed the long diameter of the second socket, recalling the proportion of
the interspaces in Pterodactylus Cuviert (Monog. cit., Tab. XXVIII, fig. 4), but
the jaw is broader in proportion to its height in Pterodactylus Fittoni.

Figure 4, a and 3, is a fragment of one side of the fore part of the upper jaw,
showing three alveoli, and agreeing in general proportions with the Pterodactylus
Fittoni.

Fig. 5 is the fragment of a jaw, showing a single elliptical socket, 5 lines in long
diameter (a), and with the plane inclined a little outward, as at 6. The widely open
cancellous structure of the bone is well shown on the inside of this fragment, as at c.

Preropactytus. Sp. inc.

Tab. I, fig. 6, is a portion of an upper jaw, including a part of two sockets, in
one of which the root of the tooth remains. Three views of this fragment are given,
of the natural size: a showing the alveolar border, b the broken margin exposing the
tooth, and ¢ the outer wall of the jaw. This part of the wall is nearly flat, very

CRETACEOUS FORMATIONS. 5

slightly convex below, and as slightly concave above, vertically; the upper margin
showing no indication of any bend or inclination to the upper border of the jaw, the
height or vertical diameter of which remains conjectural ; that it was, at least, one
third more than the portion preserved, may be estimated from the extent of the socket
of the tooth being equal with the preserved part of the wall (fig. 6, b). A coat of
roughish ‘cementum,’ one third of a line thick, is preserved upon the upper half of
the tooth-root ; below this is seen the smooth dentine ; and where it is broken, the pulp-
cavity is exposed, filled by the Green-sand matrix. The length of the implanted part
of this tooth is 1 inch 4 lines, the long diameter of the transverse fracture at the base
of the crown is $ an inch, the short diameter is 43 lines. Estimating the length of the
exserted enamelled crown to equal that of the inserted cemented base of the tooth of
a Pterodactyle—and I have known it more in the long anterior laniariform teeth—we
may assign a length of 2 inches 8 lines to the teeth implanted in the part of the upper
jaw here described. The interspace between the two sockets is 33 lines, or half that
of the long diameter of the socket; the plane of the opening of the socket, and the
interspace, present the same obliquity as they do in Pterodactylus Sedqwickii (fig. 1) ;
and as the proportion of the interspace to the socket is also the same, the present
fragment has most probably belonged to a larger individual of the same species.
Since the outer border of the sockets does not swell out beyond the outer wall of the
jaw, the fragment has been part of jaw behind the anterior swelling caused by the
proportionally large prehensile teeth; and as, from the analogy of known Ptero-
dactyles, the teeth succeeding those anterior ones are not of larger size, but are
usually smaller, at any posterior part of the jaw, we may, therefore, with due
moderation, frame an idea of the Pterodactyle to which the maxillary fragment (fig. 6)
belonged, as surpassing in size that to which the portion of jaw (fig. 1) belonged, in
the proportion in which the socket in fig. 6, a, exceeds the last socket in fig. 1, 6.
Such an idea impels to a close scrutiny of every character or indication of the true
generic relation of the present fragment in the Reptilian class ; but the evidence of the
large and obviously pneumatic vacuities, now filled by the matrix, and the demon-
strable thin layer of compact bone forming their outer wall, permit no reasonable
doubt as to the pterosaurian nature of this most remarkable and suggestive fossil.
All other parts of the Flying Reptile being in proportion, it must have appeared, with
outstretched pinions, like the soaring Roc of Arabian romance, but with the demo-
niacal features of the leathern wings with crooked claws, and of the gaping mouth
with threatening teeth, superinduced.

The last portion of jaw of Pterodactyle from the Cambridge Green-sand which
will here be described, is that figured in Tab. I, fig. 7, a, b, ec, d. It is part of the
lower jaw, and indicates a smaller individual of Pterodactylus Sedgwickii than the
specimens, figs. 1 and 2. In a longitudinal extent of 2} inches, six successive sockets
are shown, but with only the two middle pairs perfect. Their orifices have the same

6 FOSSIL REPTILIA: OF THE

obliquity as in fig. 2; and the surface of the bone between the right and left sockets
shows the same median longitudinal groove. Opposite the middle sockets the sides
of the jaw are preserved nearly to the median inferior ridge, as shown in fig. 7, ¢ ;
these sides being flat and straight, and giving the transverse section shown at fig. 7, d.
The intervals of the sockets are a little wider, proportionally, than in some of those in
fig. 2, but not more than a hinder position in the jaw would account for, without
having recourse to a distinction of species to explain it.

Two species, however, are satisfactorily established, both of them distinct from any
of the known large Pterodactyles of the Chalk, by the portions of jaws from the Upper
Green-sand near Cambridge, viz., Pterodactylus Sedgwickit, with more approxi-
mated alveoli (Tab. I, figs. 1 and 2, with probably 6 and 7); and Pterodactylus
Fittoni (ib., figs. 3, 4, and 5).

To which of these large species the teeth and bones next to be described belong is
not satisfactorily determinable, but indications of their appertaining to more than one
such species now and then occur with more or less significancy.

Teeth.

Various teeth, but few quite entire, have been rescued by the care and perseverance
of Mr. Lucas Barrett from the rubbish of fragmentary fossils accumulated during the
diggings for phosphatic nodules in the Green-sand deposits near Cambridge. Guided
by the proportions of length to breadth, by the elliptic section, and the concordance of
the minute markings on the crown and base with those on the portions of teeth, as in
Tab. L, fig. 2, d, and 6, b, remaining in the jaws of Pterodactylus Sedqwicku, many of
the above detached teeth can be satisfactorily referred to the genus, if not to that par-
ticular species.

The base or implanted part of one of the largest of these teeth is figured of the
natural size in Tab. I, fig. 10. It has belonged to a Pterodactyle as large as that
represented by the fragment of jaw (fig. 6), if not to the same individual ; it presents
the same elliptical transverse section as the implanted base of the tooth in fig. 6, 0;
shows a widely excavated pulp-cavity at the base, and gradually tapers to the crown ;
the cement, about jd of a line in thickness, is roughened by longitudinal grooves, not
continuous for any great length, but uniting, or bifurcating, in an irregular reticulate
pattern, forming long and very narrow meshes, the raised interspaces being equal
in breadth to the grooves. In a few teeth the base shows an oblique depression,
evidently due to the pressure of a successional tooth, as shown at Tab. I, fig. 8, 0;
in these the basal pulp-cavity is more or less filled up by ossification of the pulp.
The enamel of the crown seems smooth and polished, and, under the lens, shows only
extremely delicate, slightly and irregularly wavy, longitudinal, but often interrupted
or confluent, ridges. The crown is straight in a few teeth, as at Tab. I, fig. 9, but

CRETACEOUS FORMATIONS. 7

more commonly it is bent, as it is in the tooth of the great Pterodactyle from the
Chalk figured in the above-cited ‘ Monograph on Cretaceous Reptilia,’ Tab. XXVIII,
fig. 5. In general, the transverse section of the crown is less truly elliptical than that of
the base, owing to its being a little flattened on one side. The smaller teeth, probably
from the back part of the dental series, are rather more curved than the larger ones

(Tab. ILI, figs. 16—20).

Vertebre of Pterodactylus. Tab. 1, figs. 11—14. Tab. IL.

The most instructive specimens from the Cambridge Green-sand are those which
have afforded the precise and hitherto unknown characters of certain vertebre of
Pterodactylus. Viewed as indicative of the generic character of these bones, they
give the earliest known example of the ‘‘ procoelian” type of vertebrae* in the Reptilian
class, being the first cup-and-ball vertebrae, with the ‘‘cup” at the fore part of the
centrum, met with in the ascending order of strata. It cannot be doubted that this
structure prevails in the moveable vertebra of the neck and back of all Pterosauria,
and must be predicated of the Dimorphodont of the Lias as well as of the Pterodactylus
of the Green-sand, in which the structure is now clearly demonstrated. The chief
difference which the Pterodactyle presents in this respect from modern Lizards is,
that both the cup and ball are of a more transversely extended elliptical shape in
most of the vertebra of the flying Saurian.

Amongst the numerous vertebree submitted to me were specimens of united, or
partly united, ‘ atlas and axis.”

The atlas consists of a centrum (Tab. I, figs. 11 and 12, c), of two slender
styliform neurapophyses (ib., »), and of avery small discoid neural spine. The centrum
is so short as to be discoid ; it is flat where it joins and becomes anchylosed to the
axis (x), and is cencave for the occipital tubercle: this cup-is circular; its depth is
shown in the section of the anchylosed atlas and axis, fig. 12. The neurapophyses (n),
resting on each side of the upper half of the centrum of the atlas, converge and articu-
late above with two small tubercles, as shown in fig. 13, on the fore part of the neural arch
of the axis; the neurapophyses almost meet, but do not unite above the neural canal.

The body of the axis is eight times longer than that of the atlas; it expands
posteriorly, and terminates by a transversely elliptical ball (@) at the upper part of that
end, and in a pair of thick, short, obtuse, diverging apophyses (p), at the lower part.
There is a rudimental hypapophysial ridge, fig. 12, h, from the middle and toward the
fore part of the under surface of the centrum; the extent to which this surface

* Monograph of Fossil Reptilia of the London Clay,’ 4to, vol. for 1850, p. 11.
+ ‘Reports of the British Association,’ 1858.

8 FOSSILIA REPTILIA OF THE

descends below the hinder ball, and between the apophyses (p), is shown at Tab. I,
fig. 12, 2.

The centrum of the axis vertebra is confluent with the neural arch, fig. 11, n, v7; at
the middle of the side, apparently crossing the line of junction, is a large subcircular
aperture, which leads directly into the widely cancellous structure of the bone, below the
neural canal. This vacuity (fig. 11, 0) answers to the “ foramen pneumaticum” in the
vertebre of birds, and doubtless admitted a production from the air-cells extending
along the neck of the Pterodactyle into the cancelli of the osseous tissue. The neural
arch rests upon the three anterior fourths of the centrum ; it expands as it passes back-
ward ; and there, also, as it rises, until it sends off from each posterior angle the zyga-
pophysis (Tab. I, fig. 11, z), which has a tubercle above, and a flat articular surface
below, looking downward and a little outward and backward. The small tubercles
at the fore part of the neural arch, shown in fig. 13, to which the neurapophyses of
the atlas are ligamentously connected, may be the stunted homologues of anterior
zygapophyses. The neural spine begins by a low ridge between those tubercles,
increasing rapidly in thickness behind; but it has not been preserved in its full
height in any specimen.

In the smal] atlas and axis figured in Tab. II, figs. 1—4, the line of suture
between the bodies of these two vertebra is distinct. In a somewhat larger specimen,
the centrum of the atlas was separable by a smart blow, and showed the true anterior
surface of that of the axis, as shown in Tab. I, fig. 13 ; this surface is very slightly con-
cave, with a submedian prominence. The neural canal expands at its posterior outlet.

The small atlas and axis (Tab. II, figs. 1—4) not only differ in size from the
specimen (figs. 5 and 6), but also in the smaller relative size of the articular surface of
the zygapophysis, and the greater relative expansion of the back part of the centrum:
the specimen belongs to another species of Pterodactyle. On comparing the atlas and
axis of the Pterodactyle with that of the bird, the Ostrich for example, the atlas in the
bird is represented by the neurapophyses, which have coalesced below with a hypapo-
physis, forming an irregular ring of bone. The centrum has coalesced with that of
the axis, forming a small prominence, convex anteriorly, and filling up the vacuity at
the upper part of the cup excavated in the fore part of the hypapophysis; the neur-
apophyses are broad in the bird, and overlap the anterior zygapophyses in the axis ;
they meet above the neural canal, but long retain the separating fissure there, in the
Ostrich ; the centrum of the axis is broader before than behind. A short process, like
a connate pleurapophysis, from the fore part of the centrum, unites with a diapo-
physis from the neural arch to form an arterial canal. The pneumatic foramen is
behind the diapophysis, and conducts to the cancellous tissue of the neural arch. The
centrum is produced into a strong hypapophysis below the posterior articular surface ;
but not expanded laterally into transverse processes, answering to parapophyses, in
the Pterodactyle. The hinder articular surface of the centrum of the axis in the

CRETACEOUS FORMATIONS. 4

bird is convex transversely, but concave vertically, not simply convex, as in the
Pterodactyle; thus a portion of the vertebra of that reptile, notwithstanding its
pneumatic structure, might be distinguished from the vertebra of a bird.

In the ordinary neck-vertebre of the Pterodactyle the centrum is oblong, subde-
pressed, slightly compressed at the middle, subcarinate (Tab. II, figs. 11, 12, A),
or with a low obtuse hypapophysis (fig. 18) at the fore part of the under surface,
which expands laterally to join the base of the anterior zygapophyses (ib. a). The
back part of the centrum expands and bifurcates inte the short, thick, obtuse
parapophyses (figs. li and 18, 6), the anterior concavity (fig. 10, c) is a long transverse
oval, with the upper border somewhat produced : the hinder ball (fig. 8) has a similar
transversely extending elliptical figure, directed a little upwards; it appears to be
tilted up by the curve of the under surface of the centrum, above the level of the
terminal tuberous parapophyses (p). A large pneumatic foramen (figs. 7, 13, 15, 0)
of an elliptic form, opens upon the middle of each side of the centrum, close to
the anchylosed base of the neurapophysis. The texture of the centrum (fig. 19)
presents a few very large cancelli, which communicated by the pneumatic foramen with
the cervical air-cells. The smooth outer wall of the centrum is a very thin but compact
plate of bone: it becomes a little thicker where it forms the articular cup and ball.

The neural arch, between the notches of the nerve-outlets, is not quite two
thirds the length of the centrum. The hinder notch is the deepest ; the arch is low,
broad exteriorly, less concave on each side than it is before and behind (Tab. H,
fig. 17), with the four angles somewhat produced, and supporting the articular surfaces,
of which the two anterior (fig. 18, a) look upward and inward, the two posterior (fig.
16, z) downward and backward. The sides of the neural arch extend outward so as to
overhang those of the centrum (fig. 18). The posterior zygapophyses (z), do not
extend so far back as the articular ball of the centrum.

Figs. 7 to 11 give five views of the natural size of a middle cervical vertebra,
which, according to the proportions of Pterodactylus suevicus, Qnstd.,* may have
belonged to a Pterodactyle with a first phalanx of the wing-finger of about one foot in
length. In fig. 12 the under surface of the centrum is well preserved ; it differs
from that of the larger cervical vertebra (figs. 711) mm being flatter from side to
side, and in being concave instead of convex from before backward; the concave
contour being due to the median production, gradually extending into the obtuse
hypapophysis (h) at the fore part. This difference indicates that the present vertebra
had a more advanced position in the cervical series than fig. 7, which may probably
have been the sixth. The superior breadth of the neural arch over the centrum is
well shown in fig. 12; and the relative positions of the zygapophysis (s), the articular
ball (6), and the parapophysis (p), at the hinder end of the vertebra, are seen in
fig. 13, which is a side view of the same vertebra.

* Quenstedt, ‘Ueber Pterodactylus suevicus,’ 4to, 1855.

2

10 FOSSIL REPTILIA Ov tHE

Figs. 14, 15 and 16 show a smaller cervical vertebra, of a more depressed form, not
due to crushing. The centrum is much depressed ; the pneumatic foramen (fig. 15,
0) partakes of the same modification of form, and is a longer ellipse than in the
vertebra (fig. 7); the neural canal retains its normal cylindrical shape, with slightly
expanded outlets. The form of the posterior zygapophysis is perfectly preserved on
one side, in fig. 11, z, and the articular surfaces on both sides in fig. 16, z ; they are
relatively larger than in fig. 11. In fig. ]5 more of the base of the neural spine
remains than in most other specimens.

Figs. 17 and 18 are of a rather shorter and probably more advanced cervical
vertebra, but of very similar proportions ; in it the neural arch (fig. 17) is more entire
than in most specimens, the anterior (a) as well as posterior (z) zygapophyses being
preserved ; the more frequent loss of the anterior pair is due to their being more
slender and more produced. The under surface of the centrum (fig. 18) shows no
rising of the middle part, the hypapophysis having a less extended base than in the
vertebra, (fig. 12.) The inner surface of the anterior zygapophysis (fig. 18, a), is
divided by a notch from the border of the articular concavity of the centrum.

Fig. 19 gives a view of asection of a mutilated cervical vertebra, nearly equal in
size with fig. 7, and similar in form. The shape of the neural canal, the large cancelli,
and the thin superficial compact crust of the bone, are well shown in this section.

At the base of the neck, or beginning of the back, the vertebrae suddenly decrease
in length ; the hypapophysis disappears, or is represented only by a slight production
of the lower border of the anterior cup; the parapophyses are less produced, the
lower surface of the centrum is flattened, and presents the quadrate form shown in
figure 20. There is now a considerable development from the fore part of each side
of the neural arch and contiguous part of the centrum, and thereby the last cervical
or first dorsal vertebra of the Pterodactyle more resembles the corresponding
vertebra of the bird. The parapophysis, diapophysis, and rudimental rib coalesce
around the vertebraterial foramen; an oblique ridge is continued from the upper
border of the anterior articular cup upon the parapophysis ; a parallel oblique ridge is
continued from the anterior zygapophysis downward and outward upon the pleur-
apophysis ; the diapophysis makes a low obtuse projection above the pleurapophysis and
behind the zygapophysis. Above these developments the neural arch contracts
from before backward, to an extent of 5 lines, as compared with a total vertebral
breadth, anteriorly, of 1 inch 8 lines; it then rapidly expands, rising vertically at its
fore part, and developing at its back part the posterior zygapophyses, the articular
facets of which look more directly outward than in the long cervical vertebra; the
superincumbent tubercle (fig. 22, c) is more distinct from the facet (ib., ); the
posterior zygapophyses are also much more approximated than in those vertebre ;
they are separated behind by a semicircular concavity; the base of the neural spine
in the vertebra here described measured 6 lines in length by 3 in breadth. The

CRETACEOUS FORMATIONS. 11

pheumatic foramina are at the back part of the base of the diapophysis, as I have seen
them in the cervical vertebra of a Dinornis. The articular surfaces of the centrum
retain the transversely extended form, and are simply concave before and convex
behind, which at once distinguishes the Pterosaurian hind-cervical vertebra from that
of the bird.

In the dorsal region the vertebral centrum (fig. 24), retaining its shortness, gains
in depth, and presents the more usual proportions of cup-and-ball reptilian vertebre.
The under surface (fig. 20) is smooth and even, very slightly concave lengthwise,
convex transversely. The parapophysis disappears, and the diapophysis, which
alone supports the rib, after the first or second dorsal, is sent off from a higher
position in the neural arch (fig. 25).

Sacrum.

Fig. 26, Tab. II, shows parts of the bodies of three anchylosed sacral vertebre,
the first being demonstrated by part of its anterior concave articular surface (a)
for the last lumbar vertebra. The groove for the passage of the nerve notches the
back part of the parapophysis, close to the line of suture with the second sacral. In
this vertebra the corresponding nerve-notch is more advanced, leaving a short sutural
surface behind, indicative of a position of the neural arch crossing for a short extent
the line of junction of the second with the third sacral centrum. The parapophyses
of the second and third are sent off almost on a level with the lower surface of the
centrum, which is flattened.

The fore part of the sacrum of a much larger Pterodactyle, from the Cambridge
Green-sand, differing also in the less transverse convexity of the under part of the
first centrum, measures 11 lines across the shallow anterior articular concavity, and
14 lines from the lower part of the centrum to the fore part of the base of the neural
spine. The neural canal is circular and 2 lines in diameter ; above it the neural arch
rises like a vertical wall for 5 lines, where the spine has been broken off.

Caudal Vertebre.

From the number of elongated caudal vertebree in the series of fossils from the
Cambridge Green-sand submitted to me—not fewer than seven—I believe the large
Pterodactyle from that formation to have had a long tail, but moveable, not stiff
through anchylosis of the vertebrae, as in Pter. (Ramphorhynchus) Gemmingi, V.
Meyer.

The largest of these caudal vertebrae measures 14 inch in length; it is slightly

12 FOSSIL REPTILIA OF THE

contracted in the middle; the fore part of the under surface is a little produced; the
back part almost flat between the rudimental parapophyses ; the shallow anterior
concavity has resumed its transversely elliptical shape, and the hinder convexity is
defined below bya shallow groove connecting the parapophyses. There is no
pneumatic foramen, unless a small hole on each side the hinder outlet of the neural
canal have served as such; the neural arch is long and low, quite one piece with the
centrum, which extends beyond it posteriorly. It sends off short, obtuse zygapophyses
before and behind, those in front extend beyond the cup of the centrum; the sur-
faces on those behind look downward and backward. The base of the spine is coex-
tensive with the summit of the arch, but is narrow. The neural canal is much
contracted. There is no indication of a hzmal arch, either by articular or fractured
anchylosed surfaces. The diameter of the middle of this vertebra is 6 lines.

The caudal vertebra next in size measures | inch 5 lines. The base of the neural
spine begins 2 lines behind the fore part of the arch, but terminates nearer the hind
part ; the nerve-grooves notch the hinder zygapophyses.

Three more slender caudal vertebrae present each a length of 1 inch 3 lines; the
diameter at the middle is 5 lines in one, 4 lines in a second, 35 lines in the third
vertebra, showing that they become more slender without losing length. A caudal
vertebra 3 lines across the middle appears to have been nearly an inch in length;
but both extremities are injured.

Frontal Bone (2)

As it is probable that the median symmetrical portion of bone (Tab. IV, figs.
6, 7 and 8) may belong to the cranium of one of the large Pterodactyles from the
Upper Green-sand, its description follows that of the vertebree.

It is 2 inches 4 lines long; 10 lines across its broadest part; 1 inch 2 lines in
depth, to the surface where the piece has been broken away; the sides present a
smooth concave plate of bone (fig. 6), as if the piece had been nipped between a
finger and thumb, but quite symmetrically; the surface, which, on the supposition
that those smooth concave facets were inner walls of the orbits, would be the upper
one, and due to the frontal bone, is gently convex in the direction of its length, and
has a median longitudinal ridge, which expands and subsides near the end most pro-
duced beyond the lateral depressions. I have observed a similar median ridge or
rising upon the single frontal bone of the Alligator lucius, between the orbits, and
upon the double frontal, supporting the median suture, in the Rhynchocephalus lizard of
New Zealand. There is also an indication of such a median ridge in the figure of
the cranium of Pterodactylus suevicus, in Professor Quenstedt’s Memoir on that
species (4to., Tiibingen, 1855),

*

CRETACEOUS FORMATIONS. 13

The most perfectly preserved of the lateral impressions (fig. 6) is of an oval form,
1 inch 3 lines in long diameter; it is well defined from the narrower upper surface
(fig. 7) to which it stands at nearly a right angle; the curved border defining it is not
produced. The whole of the substance of the bone between the lateral plates is
occupied by a moderately open and apparently pneumatic cancellous texture (fig. 8) ;
the outer wall of bone is compact, but extremely thin; the general structure is
decidedly that of a volant Vertebrate, and most resembles that of a Pterodactyle.

The parts of the skeleton of the Pterodactyle which would afford a symmetrical
median piece of bone, comparable with the present fragment, are—the sternum, the
fore part of the upper and lower jaw, the sphenoid at the base of the skull, and the
parietal and frontal bones at the upper part of the skull. The absence of any trace of
cranial cavity at the lower fractured surface, more than an inch below the outer
surface, opposes the choice of the parietal with lateral impressions of temporal
fosse: there remains, therefore, the frontal with the interpretation of the lateral
depressions as parts of the orbits; but the depth of the smooth impressed plates, and
their divergence as they descend, oppose this interpretation. I have no evidence of
sternal ends of coracoids which would require articular depressions of such size and
shape as the lateral ones on the fragment in question, on the hypothesis that it may
be from the fore part of the sternum. Upon the whole, therefore, I have to acknow-
ledge a degree of uncertainty as to the exact nature of the present fragment of the
skeleton, most probably, of some large Pterodactyle.

Scapular Arch.

The mechanism of the framework of the wings in the Pterodactvle is much more
bird-like than bat-like. The scapular arch is remarkably similar to that of the bird
of flight. It consists of a scapula and coracoid, usually anchylosed where they combine
to form the shoulder-joint.

The cavity for the head of the humerus, in Pterodactylus macronyz * (Tab. III,
fig. 6), is oval, with the great end formed by the scapula; it is concave verti-
cally, or in the direction of its long diameter, convex transversely, but least so
near the scapula. If these proportions hold good in other species, they would
serve to determine the scapular or coracoid portion of a glenoid cavity, when, as in
the case of the fossils here described, the rest of the scapular arch had been
broken away.

The upper (scapular) border of the glenoid cavity is prominent and well defined ;
the bone is moderately constricted beyond it, from without inward, whence the

* Buckland, ‘ Geological Transactions,’ 2d series, vol. iii, pl. xxvii, x, 9.

14 FOSSIL REPTILIA OF THE

scapula extends upward and backward, as a slightly bent sabre-shaped plate, a little
twisted on itself. The coracoid is thicker, straighter, and shorter than the scapula ;
it is rather suddenly expanded at the sternal end, where it is most compressed:
the scapular end developes a protuberance below the glenoid cavity.

The scapular arch in Pterodactylus giganteus, Bwk., from the Chalk of Kent
(‘Monog. Cretaceous Reptiles,’ 1851, p. 93, Tab. XXXI, fig. 7), was distinguished
by a tuberous (acromial) process from the scapula, near the glenoid cavity, the corre-
sponding anterior process from the coracoid being well marked.

The fossil fragment from the Cambridge Green-sand (Tab. II, figs. 1 and 2)
consists of the coalesced extremities of the scapula (a) and coracoid (6), where they form
the glenoid cavity for the humerus. The margins of the cavity are in part abraded,
but its long diameter cannot have been less than 1 inch 3 lines; it is concave
vertically, rather convex transversely below, but plane, or a little concave, in that
direction at the upper or scapular end. The cavity is transversed obliquely by a
depression pretty equally dividing it, and indicating the respective shares of the
scapula and coracoid in its formation prior to the anchylosis of those two bones.
The end of the scapula, near the cavity, would present an unequally three-sided figure
in transverse section, the side looking inward ana that looking forward being
concave, the side looking outward convex. Half an inch above the border of the
glenoid cavity is the fractured base of the (acromial) process answering to that in
Pterodactylus giganteus, but which is more feebly developed in Pterodactylus
macronyx, Bkd., and Pterodactylus suevicus, Qnstd. Beyond this process the bone
rapidly contracts in size, and presents an oval transverse section, as at a, fig. 2,
Tab. III.

The surface of the coalesced extremities of the bones which is applied to the
thorax is concave in every direction, and an inch in’ breadth, with a long narrow
(pneumatic) aperture near its hinder border. The anterior production of the coracoid
has been broken away at ¢ (figs. ] and 2), the coracoid quickly contracts as it recedes
from the humeral articulation to a size and shape shown by the section b (fig. 2).
The size of the entire scapular arch, according to that of Pterodactylus macronyx, is
shown by the dotted outlines in fig. 1.

Fig. 3 shows the articular surface of the scapular arch of a Pterodactyle of larger
size than the preceding specimen ; the oblique groove indicative of the portions con-
tributed by the scapula and coracoid to the cavity is well marked, as it also is in the
corresponding fragment of the scapular arch of the smaller Pterodactyle (fig. 4). In
the still smaller but similar fragment of the scapular arch (fig. 5), the posterior
concave surface shows the long (pneumatic ?) foramen very distinctly, and also a
trace of the primitive separation of the scapula and coracoid. If this specimen has
belonged to a young individual of either of the two larger species, it shows that the
union of the two bones takes place at an early age. In the bird, although the early

CRETACEOUS FORMATIONS. 15

and extensive coalescence of originally distinct bones is a characteristic of the skeleton,
the scapula remains distinct from the coracoid, and the persistent suture traverses the
glenoid cavity. The coracoid is shorter and straighter in birds than in Pterodactyles,
but is commonly broader, and with a longer and stronger anterior process.

Humerus.

The portion of bone figured of the natural size in Tab. III, fig. 7, shows an
articular surface of a reniform figure, convex in its shorter diameter, less convex
upon the more prominent half, lengthwise, and slightly concave lengthwise at the side
which is hollowed out. The smaller end of the surface (a) has been produced into a
process, here broken away, and the fracture is coextensive with the length, in the
direction of the shaft of the bone, of the fragment, which is nearly two inches; the
larger end of the articular surface (b) seems not to have sent off such a process ; but
the back part of this end is broken away. The pterosaurian nature of the fragment
is shown by the thinness of the compact wall of the shaft below the articular surface,
and by the wide cancelli. The general resemblance of the articular surface, in shape,
to that of the humerus of the Wealden Pterodactyle (Pt. sylvestris, Ow.) figured in
the ‘ Quarterly Journal of the Geological Society,’ Dec., 1845, vol. ui, p. 100, fig. 6;
and to that of the more complete humerus of Pterodactylus suevicus, Qnstd., loc.
cit., but especially to the articular surface of the portion of bone of a smaller Ptero-
dactyle (Tab. HI, figs. 14 and 15), which exhibits more distinctive characters of a
humerus, have led me to refer the fragment in question (fig. 7) to the proximal end
or head of that bone in one of the large species above established by maxillary
characters.

The end of the articular surface (a) answers to the outer’ plate or process (g) in
Pterodactylus sylvestris, and the fractured surface behind the end (b) might well have
been the base of a shorter and thicker process, like that marked f in Péter. sylvestris.
Determining, by these analogies, that @ is the outer or radial, 4 the inner or ulnar,
end of the transversely extended head of the humerus; that the convex side is the
fore part, and the concave one the back part, of the same bone; it may next be
remarked that the inner half of the fore part of the articular surface is extended further
and more convexly upon the shaft than the outer half, which meets the vertical plane
of the shaft more abruptly ; but the form of this part of the head of the humerus is
better shown in the next specimen.

This fragment (fig. 8) is the head of the opposite humerus of a Pterodactyle of
equal size with the preceding. The boundary of the articular surface near the outer
process (a) is very slightly raised, with a few short ridges at right angles, indi-
cative of the firm attachment of the capsular ligament; an oblique line divides the

16 FOSSIL REPTILIA OF THE

more abruptly defined outer half of the surface from the inner anteriorly more convex
half. The anterior surface of the fore part of the shaft of the humerus, here
preserved, is impressed by longitudinal reticulate markings. The total length
of the humerus, according to the proportions of the length of that bone to the
breadth of its proximal articular surface in Pterodactylus suevicus,* would be 10!
inches.

Fig. 9 shows well the minutely punctate surface of the articular head of the
humerus ; the portion of the fore part of the shaft preserved with this shows that the
fine reticulate markings are limited to a short distance below the head, and that the
rest of the outer surface of the shaft here preserved is smooth. The extent of the
base of the outer plate or process is 1 inch, the long diameter of the articular surface
of the head being | inch 3 lines.

The fragment of the head of the humerus (Tab. III, fig. 10) is remarkable for
the well-defined ridge bounding the anterior convex part of the articular surface.

The proximal end of the smaller humerus (fig. 11) includes nearly two inches of
the shaft, of which a front view is given in fig. 12, and a back view in fig. 13. The
base of the outer process (g) shows the same proportion to the long diameter of the
head, as in fig. 9. The fractured surface along the opposite side of the shaft (/) seems
to show that this border had been produced into a ridge or plate, as in Ptero-
dactylus sylvestris. ~The back part of the shaft between these plates is concave
transversely, but rather convex lengthwise; the opposite conditions prevail on the
fore part of the bone. Here, towards the base of the outer process, is a small,
apparently pneumatic, oblong foramen.

The smaller proximal end of humerus (figs. 14 and 15), shows a larger proportion
of the process (f) which extends the bone in that direction beyond the articular head.

All these specimens show that, in the Pterodactyles from the Green-sand, there is
a plate or process with a shorter base, extending close to the articular surface of the
head of the bone, and that there is a plate, with a larger base, extending farther from
the articular head at the opposite side of the bone.

The fragment (figs. 1, 2, and 3, Tab. IV) shows part of the articular extremity
of one of the long bones of the wing. The articular surface has been partially
divided into what might be called, were they entire, two condyles (a and 6). The
most perfect of these divisions shows a slightly convex surface (figs. 1, and 2, a, a,)
occupying its major part, andasmall well-defined flat surface (figs. 1, and 3, c,), placed
obliquely. So much of the other division as is preserved likewise shows two facts

* See the plate in Quenstedt’s ‘ Memoir,’ above cited.

CRETACEOUS FORMATIONS. 17

one, which we may call the anterior (d), is convex and of small extent, and behind it
is a well-defined part of a concave surface (b). At the fore (?) part of the bone
(fig. 2) the two convex surfaces extend a little upon the shaft (a), and are divided
from each other by a moderate median depression ; where the thin smooth outer crust
of bone has been worn away, the small superficial cancelli are exposed. At the back(?)
part (fig. 3), where the major part of the bone is broken away, the larger cancelli
are exposed.

Guided by considerations of size, the fragment (Tab. IV, figs. 1—3) might
form the opposite end of the bone indicated by the articular ends (Tab. III, figs. 7,
and 8). Iam not acquainted with the precise configuration of the distal end of the
humerus, in any Pterodactyle ; indeed, the articular surfaces of very few of the bones
of this remarkable reptile have been perfectly preserved, so as to be recognisably
delineated and described. From general analogy, however, one should scarcely be
prepared to find so feeble an indication of divisions into condyles, an absence of
general convexity, and a presence of a well-defined concavity in one condyle, and as
well-defined a flattened or feebly concave facet in the other condyle, of the distal end
of a humerus. The form of articulation above described would seem rather to be that
of the end of an antibrachial bone adapted to join the bones of a carpus. But, on
the hypothesis of the fragment in question being either proximal or distal, and of a
radius or ulna, it expands our ideas of the bulk of the Green-sand Pterodactyle even
beyond those suggested by the manifestly head of the humerus (Tab. III, fig. 7).
The present description and figures will at least help, it is hoped, to forward a precise
knowledge of the osteological characters of tue P/erosaurians.

Assuming that we have in figs. 1—38, Tab. IV, the articular end of an
antibrachial bone, then, according to the proportion which the broadest end of one
of these bones bears to its total length in the Pterodactylus suwevicus, the length of
such antibrachial bone in the great i’terodactyle of the Green-sand here indicated
would be 16 inches. ‘The total length of wing will be calculated on this basis at the
conclusion of the present Monograph.

The fifth or wing-metacarpal.

The trochlear joint of the bone (Tab. IV, figs. 9—11) belongs to the distal end of
the metacarpal of the fifth or wing-finger. The pulley is more complex, in the large
Pterodactyles here described, than it is in similar trochlear joints of other animals ;
there are three convex ridges, a, b, c, which traverse the articular surface from behind
forward, describing rather more than half a circle ; the middle ridge, c, is less prominent,
and of less extent than the lateral ones which form the sides of the pulley. The direc-
tion of the ridges is rather oblique, and one which, to help the description, may be called

9

re)

18 FOSSIL REPTILIA OF THE

the outer ridge, is rather more produced and of a less regular curve than the inner ridge.
The outer ridge, a, begins by a rising at the middle of the fore part of the distal end of
the shaft, which bends obliquely outward and meets the outer angle of that part of
the shaft where the outer trochlear ridge begins to be prominent; this ridge then
extends with a feeble convex curve to the back part of the trochlea, where the con-
vexity of the curve increases, and it terminates by projecting a little beyond the level
of the outer almost flattened side of the trochlea (fig. 10). The articular surface, as it
extends from the margin of this element of the trochlea inward, is first gently convex,
then sinks to a concave channel by the side of the low median convexity. The inner
ridge 6, begins from the inner side of the fore part of the bone, and describes a pretty
regular semicircular curve as it extends backward and a little outward, to terminate
near the middle of the back part of the distal end of the shaft; thus owing to the
termination of the inner ridge near the middle of the back part, and to the
beginning of the outer ridge near the middle of the fore part, of the metacarpal bone,
these principal ridges of the trochlear joint recede from each other at the middle of
the joint, and approximate at the fore and back ends of the joint. As the back ends
of the two lateral ridges are on the same transverse line, and the front end of the
inner ridge rises higher upon the shaft than that of the outer ridge, this is by so much
the shorter of the two. The low middle ridge ¢, is much shorter than either of the
lateral ones, being confined to the lower and middle part of the trochlea, to which it
gives an undulating transverse outline (fig. 11).

The figure of the metarcarpal bone of the wing-finger, in Pterodactylus
suevicus, Qnstd., does not show any trace of the mid-rising of the distal trochlear
joint. The back surface of that of the left wing shows a wide and moderately deep
excavation along the upper three fourths of the shaft. A portion of a similarly
shaped shaft of a long bone, in size matching that of the trochlear extremity (fig. 10),
is represented in Tab. IV, figs. 4and 5. Although both ends are broken away,
yet the degree of expansion toward the upper end shows that this was not very far
from the proximal articulation. The shaft is three-sided; two of the sides are nearly
flat or very feebly convex; they meet anteriorly at an acute angle, but this is
rounded off as shown in the transverse sections of figs. 4 and 5; the third and
shorter side is concave in the degree shown in the same sections. The lower of these
(fig. 5), indicates the extreme thinness of the compact wall of the bone, and the size
of the cancelli occupying that part of the shaft.

The portions of the wing-bones of the Pterodactyles of the Cambridge Cian
sand, here described and figured, show the same superior proportions over those of
the great Pterodactyles from the Kentish Chalk, described and figured in a former
Monograph, 4to., 1851, as do the portions of jaw bones and teeth.

The long diameter of the largest of the wing-bones, figured in Tab. XXX, fig. 1,

CRETACEOUS FORMATIONS. 19

4to, 1851, e.g., is 2 inches 2 lines; that of the wing-bone, figured in Tab. IV, figs.
1—3 of the present Monograph, is 3 inches. The transverse diameter of the distal
end of the humerus of Pterodactylus grandis, Cuv., the largest species hitherto
obtained from the Lithographic Slates of Germany, is 1 inch 3 lines; neither the
radius, ulna, nor metacarpal of the wing-bone of the same species presents a diameter
of its largest end equalling | inch.*

The articular end of the long wing-bone (Tab. IV, figs. 1—3), being most pro-
bably that of an antibrachial bone, and the total length of the bone, whether radius
or ulna, being, according to proportions of either of these bones in Pterodactylus
suevicus, 16 inches, the following would be the length of the other long bones of the wing
in the large Pterodactyle to which the above-cited specimen belonged, according to the
proportions which those bones bear to the radius or ulna in Péerodactylus suevicus -

Ft. In. Lines.

Humerus 1 0 0
Radius us 1 4 0
Metacarpus of wing-finger . 1 8 0
First phalanx of do. 2 3 0
Second do. do. 1 9 0
Third do. do. 1 5 0
Fourth do. do. 1 1 0

Total length of long-bones of one wing 10 6 0

Supposing the breadth of the Pterodactyle between the two shoulder-joints to be
8 inches, and allowing 2 inches for the carpus and the cartilages of the joints of the
different bones, in each wing, we may then calculate that a large Pterodactylus Sedqwickii
would be upborne on an expanse of wings of not less than 22 feet from tip to tip.

I look forward with confidence to future acquisitions of remains of the truly
gigantic Pterodactyles of the cretaceous periods, more especially from the Green-
sand locality, near Cambridge, as a means of throwing more light on the peculiar
osteology of the extinct flying reptiles.

For the opportunities at present afforded me, I have to express most grateful
acknowledgments to my old and much esteemed friend the Rev. Professor Sedgwick,
F.R.S.; to the acute and active curator of the Woodwardian Museum, Mr. Lucas
Barrett, F.G.S.; to James Carter, Esq., M.R.C.S., Cambridge ; to T. W. Beddome,
Esq., of Trinity College, Cambridge; and to the Rev. G. D. Liveing, M.A., of St. John’s
College, Cambridge, to whom I am indebted for the lower jaw of Péerodactylus
Sedgwicku (Tab. I, figs. 2, a, b, c, d).

* These admeasurements are derived from the excellent figures of a recently acquired specimen, well
described by Professor ANDREAS WacnurR of Munich, in the ‘‘ Abhandlungen der Kais. Bayer. Akademie
der Wissenschaft,” Band iii, p. 663, taf. xix.

ene

beet

ALPR

ee oe oy eT. bY) ing 2

eA eh eee, all 4

Fig.
. Fore part of the upper jaw of Pterodactylus Sedqwickw: a, side view; b, under

i)

12

13.
14.

(eM), 1

Genus Pterodactylus.

view, or palatal surface; c, front view or end; d, section of fractured
opposite end.

Fore part of the lower jaw of Pterodactylus Sedgwickii: x, side view; 6, upper
view ; ¢, section of fractured end ; d, one of the sockets, magnified, showing
the protruding apex of a young successional tooth.

. Fore part of the upper jaw of Pterodactylus Fittoni: a, side view; b, under

view ; c, section of fractured end.

. Another portion of the upper jaw of Pterodactylus Fitfoni: a, side view; 6, section.
. A fragment of the upper jaw with one socket of Pterodactylus Fittoni: a,

under view; 6, outside view; c, inside view, showing the large cancelli.

. A fragment of the upper jaw of a large Pterodactylus Sedgwickit: a, under view ;

b, end view, showing the deep implantation of the tooth; c, outside view.

. Part of the under jaw of Pterodactylus Sedqwickwu: a, side view; 6, upper

view, or that next the mouth ; c, under view ; d, section.

. Base of a tooth, impressed by the apex of a successional tooth, at o.
. Crown of a tooth.

10.
ae

Base of a large tooth, showing the longitudinally wrinkled cement.

Anchylosed atlas and axis: ¢. centrum of atlas; cz, centrum of axis; 4, articular
ball of axis; p, inferior process; 0, pneumatic foramen; n, neurapophysis
of atlas; xz, neural arch of axis; z, posterior zygapophysis and tubercle of
axis.

Section of anchylosed atlas and axis: 4, median hypapophysis.

Front view of the axis vertebra from which the atlas has been detached.

Back view of the same vertebra.

All the foregoing figures are of the natural size, and from specimens in the
Woodwardian Museum of the University of Cambridge (with the exception
of fig. 7 in the Private Collection of the Rev. G. D. Liveing, M.A., of St.
John’s College, Cambridge) ; they were obtained from the Upper Geen-sand
(Neocomian), near that town.

Ee

TAB se

Vertebree of Pterodactylus Sedgwickii and Pter. Fittoni.

Fig.

1. Front view of anchylosed atlas and axis.

2. Back view of the same.

3. Side view of the same.

4. Under view of the same: a, anterior tubercle, or rudiment of zygapophysis, of
axis ; z, posterior zygapophysis, of axis; c, centrum of atlas; », infero-
posterior processes of axis; 2, articular ball of axis.

5. Front view of a larger specimen of atlas and axis.

6. Under view of the same, indicative of a species distinct from fig. 4.

7. Side view )

8. Back view |

9. Upper view + of a middle cervical vertebra.

10. Front view |

11. Under view J

a Sen ; of a cervical vertebra.

14. Upper view j

15. Side view ‘ of a cervical vertebra.

16. Under view J

iis oes a } of a more complete cervical vertebra.
18. Under view

19. Section of a large cervical vertebra.

20. Under view }

21. Front view f of an anterior dorsal vertebra.
22. Side view /

23. Front view of a lumbar vertebra.

ae a aes } of a dorsal vertebra.

26. Under view of three anchylosed sacral vertebre.

All the figures are of the natural size, and from specimens in the Woodwardian
Museum of the University of Cambridge, which were found in the Upper
Green-sand (Neocomian) near that town.

TINE

Jos Dinkel Jith

iv hy
ivy aC!

Fig.

14.

15

CAB ute

Pterodactylus Sedqwickii and Pterodactylus Fittoni.

Humeral end of anchylosed scapula a, and coracoid 6, with the glenoid articular
cavity. The letter ¢ indicates the base of the broken-off anterior or angular
production of the coracoid.

. Front view of the same specimen.

. Similar view of the glenoid articular cavity of a similar sized Pterodactyle.

. Glenoid articular cavity of a smaller specimen, and probably different species.

. Inner surface of the anchylosed humeral end of the scapula and coracoid of a still

smaller Pterodactyle.

. The scapulo-coracoid arch of Pterodactylus (Dimorphodon) macronyx, Bkd.
. The articular head of the right humerus of a large Pterodactyle.

. The articular head of the left humerus of a large Pterodactyle.

. The articular head of the left humerus of a smaller Pterodactyle.

. The articular head of the right humerus of a similar sized Pterodactyle.

. The articular head )

. (The convex side) / of the proximal end of the humerus of a Pterodactyle.

. (The concave side)
(The convex side) | of the proximal end of the humerus of a smaller Ptero-
(The concave side) dactyle.

16—20. Different teeth of Pterodactyles.

All the figures are of the natural size, and from specimens in the Woodwardian
Museum of the University of Cambridge, which were found in the Upper
Green-sand (Neocomian) near that town.

Viaiis

=
or

to

we vO

(—
—- OO ON DN

—_—

AGS GaliVe

Pterodactylus Sedgwickti and Pter. Fittoni.

. Articular end,

Front (2) surface

. Back (?) fractured) surface
Side view _} of part of the proximal end of the metacarpal of the 5th or wing-
Back (?) el finger.

. Side view

Upper (2?) view of a symmetrical (probably frontal) bone.

| of a long bone of the wing.

. Opposite fractured surface /
; es oa | of the trochlear distal extremity of the metacarpal of the 5th or
. Side view Ba Oo
: | wing-finger.
. Back view
All the figures are of the natural size, and from specimens in the Woodwardian
Museum of the University of Cambridge, which were found in the Upper
Green-sand (Neocomian) near that town.

LN.

cas

MONOGRAPH

ON

THE FOSSIL REPTILIA

OF THE

CRETACEOUS FORMATIONS.

SUPPLEMENT No. II.

Pacus 27—30; Prater VII.

DINOSAURIA (Ictanopoy).

BY

PROFESSOR OWEN, D.C.L., F.R.S., F.L.S., F.G.S., &.
Issued in the Volume for the Year 1858.

LONDON :
PRINTED FOR THE PALHONTOGRAPHICAL SOCIETY.
1861.

SUP Pie ME NI GNox IT) *

TO THE

MONOGRAPH

ON

THE FOSSIL REPTILIA

OF

THE CRETACHOUS FORMATIONS.

Orper—DINOSAURIA, Owen.

Genus—Ieuanopon, Mantell.

Dentition of the Upper and Lower Jaws (Tab. VII).

In the year 1858 a considerable part of the skeleton of an Iguanodon was dis-
covered in the Lower Greensand formation at Black Gang Chine, Isle of Wight.

The workmen disposed of various parts of it, as opportunities offered;
and before steps could be taken to secure the whole for the British Museum,
portions of jaws and teeth had passed into the hands of private collectors. From
the best account of the discovery that I could collect, it appeared that the entire
cranium, somewhat dislocated, had been brought to light by the quarrymen; but
the bones were in a peculiarly fragile, crumbly state, and only the firmer parts of
the jaws, lodging the teeth, were secured, and these portions in fragments. Some
of them, of both upper and lower jaws, are now in the British Museum; and
learning that other portions had been acquired by George Robbins, Esq., F.G.S.,
of Castle, near Bath, I addressed a letter to that gentleman, who very kindly
brought his specimens to London, and liberally placed them in my hands for de-
scription. The largest fragment fitted on to another portion of the jaw in the
British Museum, adding to its value as an illustration of the most interesting of
the hard parts of the Iguanodon. It consisted of a fragment of the left upper jaw,
with three teeth ; there were also three fragments of the left ramus of the lower
jaw, with one or more teeth in each.

The germs of the new teeth are developed, in all Saurians, as is well known,
on the inner or mesial side of the base of the old teeth.f One of the teeth in the

* This Memoir was given as “Supplement (No. II) to the Monograph on the Iguanodon,” in the
1858 volume.

+ Of this character Professor Melville ably availed himself in determining the upper and lower teetk of
the Iguanodon, in the joint memoir, by Dr. Mantell and himself, in the ‘ Philos. Trans.’ for 1848.

28 FOSSIL REPTILIA OF THE

portion of the upper jaw (Tab. VII, figs. 1, 2, and 3, m) has its summit obliquely
worn from above downward and outward to the enamelled trenchant border ; the
contiguous tooth, x, the summit of which has not suffered abrasion, is pressing
upon the smooth, concave side of the older tooth; a third tooth, o, the crown of
which is still buried in the alveolus, has the same relation to the more advanced
tooth, x. The smooth, concave sides of these teeth, shown in fig. 1, are, therefore,
the inner or mesial ones, and the flat surface of bone extending from the alveolar
border is the inner or palatal alveolar wall of the maxillary bone.

The crown of each tooth shows that more definite and prominent primary
ridge on their outer side (a, figs. 2, 3, and 4) which is characteristic of the teeth
of the upper jaw of the Iguanodon.

In figs. 5 and 6, three of the teeth (m, 2,0) show precisely the same stages of
growth as the foregoing one; one (m) has the summit abraded from the enamelled
trenchant border downward and outward; in a second (nm) the crown is extri-
cated, but not worn; ina third (0) the major part of the crown is still in the
formative cell. The relative position of these three teeth to each other is, in one
respect, the reverse of those in fig. 1. The convex ridge side of the crown of
the second tooth (fig. 5, 2) partly overlaps (instead of being overlapped by) that
of the first (m), and it is similarly overlapped by the germ of the third (0).
The side of the jaw to which the newer teeth (ar, fig. 5) are nearest is the
inner one ; the smooth, longitudinally concave, side of the tooth is next the outer
side of the jaw (fig. 6); they belong to the lower jaw, and they show the formal
characters of mandibular teeth; the primary ridge, a, is less produced.

The upper teeth (figs. 1—4) are narrower, in the direction of the length of the
jaw, or from ¢ to d, and are less curved than the lower; the fang and base of the
crown are thicker, transversely to the jaw or from a to g (fig. 4). The primary
ridge, a,is more prominent; the secondary ridges, 4, are less constant and less
marked than in the lower teeth. Both fore (c) and hind (d) borders at the
base of the crown are entire, and are bent or produced slightly outward, bound-
ing the transversely concave arew between them and the primary ridge; they
slightly diverge as the crown expands; along its apical half both borders are serrate
or serro-lamellate, converge, and, with a slight difference of contour, meet at the
apex of the unworn crown formed by the termination of the primary ridge (x 0, fig. 2).
This ridge, a, commencing in a tooth 33 inches long about 1 inch 8 lines from the
base, becomes thinner and sharper as it projects, which is to the greatest degree
before it reaches the middle of the crown, whence it gradually subsides to the
apex; its longitudinal profile is a slight curve convex outward: this ridge
divides the outer side of the crown unequally, the front area, a, ¢, being broader,
sometimes nearly twice the extent of the hind one, a, d. The dentated margin of
the crown to which the primary ridge is the nearest is the posterior one, and is

CRETACEOUS FORMATIONS. 29

the shortest and straightest (fig. 2, a). A few, irregular, linear, minute, ridges
mark the enamel in both aree; being more numerous, from three to five, in the
wider one, and not more than one or two of these extend from the base to the
apex of the crown; at the base they converge and sometimes unite as they descend.

The fore part of the tooth is slightly hollowed at the basal half of the crown
(fig. 4, e); the fossa, which is elongated and concave transversely, gradually filling
up towards the apex; below the middle of the crown, at the apical half, the fore
part of the crown (fig 1, e) is convex transversely. The hind part of the tooth
(fig. 4, /) is impressed by a longer, wider, and shallower depression, beyond
which it shows an oblique, rather flattened than convex, surface. -The inner part
of the tooth, which is narrow in the fang (fig. 4, g), gradually expands upon the
crown to near the apex, where it again grows narrower; at its broadest part
it is flattened or even a little concave transversely, but rounds off convexly into
the fore and hind parts of the crown (fig. 1, m).

The abraded surface of the crown is remarkably smooth and level; it inclines
from before downward and backward, and more so from within downward and
outward in the upper jaw.

The longitudinally convex and ridged part of the crown being external in the
upper teeth, and the position of the primary ridge determining the fore and hind
borders of the crewn, a detached tooth may be at once referred to the right or
left maxillary bone. The germ of the successional tooth causes an excavation on
the inner, and generally towards the hinder, part of the base of the one in use.

In a left upper tooth, with one fourth of the crown abraded, and projecting
1 inch 9 lines from the alveolar border, the crown of the successional tooth had
its apex on a level with that border, and on the inner and back part of this crown
was the thin shell of the apex of a third tooth in the successive series.

The outer alveolar wall of the upper jaw is very thin at the outlet of the
sockets, and is a little produced at the intervals of the teeth; it rapidly increases
in thickness towards the base of the sockets.

The inner or palatal wall also thins off toa crenate edge; so much as is preserved
in the specimens examined was flat and smooth, as in fig. 1. The grinding sur-
face of the tooth (m), of which one third of the apex had been worn away by mas-
tication, projected only about half an inch from the inner alveolar margin.

The lower or mandibular teeth of Iguanodon have a broader crown, and
a fang less thick transversely to the jaw than the upper teeth; they are more
curved lengthwise, the curvature being concave outward, contrary to that of the
upper teeth. The outer side of the tooth (fig. 6, m, and fig. 11, o) is smooth and
convex from the fore (¢) to the hind (@) border, its greatest breadth being opposite
the middle of the crown. ‘The primary ridge, commencing at the enamelled base
of the inner and flatter part of the crown (fig. 5, m,a, and fig. 11, a), slowly rises, and

30 FOSSIL REPTILIA OF THE CRETACEOUS FORMATIONS.

is most marked along the apical half, but is here much less prominent than in the
upper teeth; it divides the crown into two unequal are, the front one
(fig. 5, m, a,c) being at its broadest part nearly twice the breadth of the back one
(ib., a, d). The front area is pretty equally subdivided by a low, secondary,
longitudinal ridge, 4, each division being feebly concave across. The angle
between the entire (fig. 11, 7) and serrated (fig. 11 ¢,) parts of the borders of the
crown is more marked than in the upper teeth; the basal part of the posterior
border (fig. 11, @) seems as if it were pushed inward and forward by the crown -of
the succeeding and less developed tooth. ‘The anterior serrated border (fig. 5, x, ¢)
is at first straight, then describes a bold, convex curve as it approaches the apex.
The posterior border (ib., @) passes almost to that apex in a straight line before it
is rounded off to the obtuse summit, where the primary ridge terminates. At the
fore part of the tooth (fig. 9) the fang is convex, and the basal half of the crown
shows a lanceolate depression, slightly concave across. The back part of the
tooth (fig. 8) shows a longer, shallow depression, s, extending over the upper half
of the fang and lower third of the crown. The inner or longitudinally convex
side of the narrow fang, in worn teeth, is sharply excavated, even to expose the
pulp-cavity, by the crown of the successional tooth (figs. 13 and 14, »).

The apex of the crown of a young successional tooth is shown at 7, on the
inner side of the tooth» in fig. 5. The remnant of the fang and alveolar
depressions of the old and shed teeth are shown at ¢, ¢ on the outer side of the
succeeding teeth, in fig. 7. Both are from the lower jaw.

The upper part of the outer alveolar wall of the mandible bends out, so as to
be concave vertically ; its border is more deeply crenate than in the upper jaw.
A vascular canal runs about an inch and a half beneath it, from the oblique
orifices open upon the outer surface of the mandible.

Figs. 10—14, in Tab. VII, from the dental series of the same individual, dis-
covered in the Greensand of Black Gang Chine, exemplify different degrees of de-
struction of the tooth by abrasion and absorption. Fig. 10 is an unworn tooth from
the fore part of the lower jaw. Figs. 11—14 show the size of the majority of the
teeth. In figs. 18, 14 the letter » marks the cavity caused by pressure of the new
or successional tooth; in fig. 14 it has laid open the pulp-cavity of the old tooth.

Fig. 15 shows the inner side, and fig. 16 the fore part, of a mandibular tooth
of a young Iguanodon, from the Upper Greensand near Cambridge. The inner
side of the fang shows the excavation due to the pressure of the successional
tooth (p, fig. 15). Fig 17 shows the outer and inner sides of a smaller tooth
of an Iguanodon, from the same formation and locality. All the evidences
of Iguanodon which have yet reached me therefrom indicate a small size; but
whether this may relate to the immaturity of the individual, or to a small variety,
T am uncertain.

TAB. VII.

Iquanodon Mantelli.

. Fragment of the left upper jaw, with three teeth, inner side.

. Ditto, outer side.

. Ditto, free or working surface of the crowns of the teeth.

. Fragment of the upper jaw, with two teeth, showing their transverse section.
. Fragment of the left ramus of the lower jaw, with four teeth, inner side.
. Ditto, outer side.

. Ditto, upper view.

. A lower tooth, back surface.

. Ditto, front surface.

. An unworn lower tooth; 2, inner, 0, outer surfaces.

. A lower tooth, slightly worn ; 2, inner, o, outer surfaces.

. A lower tooth, more worn; 7, inner, 0, outer surfaces.

. A lower tooth, more worn ; 2, inner, 0, outer surfaces.

. A lower tooth, worn to the fang ; 2, inner, 0, outer surfaces.

All the foregoing figures are of the natural size, from parts of the same
individual Iguanodon, discovered in the Lower Green-sand formation at
Blackgang Chine, Isle of Wight. In the British Museum, and in the
Collection of George Robbins, Esq., V.G.S., of Bath. Figs. 15, 16, and
17, are from the Upper Green-sand formation near Cambridge.

MONOGRAPH

ON

THE FOSSIL REPTILIA

OF THE

CRETACEOUS FORMATIONS.

SUPPLEMENT No. III.

Paces 1—25; Piates [—VI.

PTEROSAURIA (Preropactrrtvs)

AND

SAUROPTERYGIA (PoLyprycHonon).

BY

PROFESSOR OWEN, D.C.L., F-RS., F.LS., F.G.S., &c.

Issued mm the Volume for the Year 1858.

~ LONDON:
PRINTED FOR THE PALHZONTOGRAPHICAL SOCIETY.
1861.

SW IZ II INIT CONS TO)

TO THE

MONOGRAPH

ON

PE Oss i” kN PT tales

OF

THE CRETACEOUS FORMATIONS.

Orvper—PTEROSA URIA, Owen.
Genus—Preropacryuus, Cuvier.

In former monographs on the fossil reptilia of the Upper Green-sand of
Cambridgeshire,* I have described, figured, or referred to, parts of a Pterodactyle,
from an individual surpassing in size that to which the portions of upper and
lower jaw{ belonged on which the species dedicated to Professor Sedgwick
was founded. Such fossil evidences of more gigantic flying reptiles, showing
no better distinctive characters, were deemed, probably, to belong to the
Pterodactylus Sedgwickii,t the then largest known species of the genus.

I am now, however, enabled to adduce, from the more recently acquired
additions to the Woodwardian Museum at Cambridge, supplied to me by the
same unfailing liberality of the eloquent Professor, evidences of a much larger
Pterodactyle, distinct, in regard to the form of the skull, from any previously
known, and one which, assuming that the portion of upper jaw of Pterodactylus
Sedgwicki (Tab. I, fig. 1, ‘Monograph’ of 1857) belonged to a full-grown
specimen, must have acquired at least double the dimensions of that species.

* «Monograph on Fossil Reptilia of the Cretaceous Formations’ (1857), tab. i, p. 6; tab. iv, figs. 1,

2, and 3.
+ Ibid., t. i, figs. 1 and 2. t Ibid., p. 5.
1

2 FOSSIL REPTILIA OF THE

PTERODACTYLUS sIMUS, Owen.

Jaws and teeth (Yab. I, figs. 1—10).

The first evidence I have to offer of this truly gigantic flying reptile consists
of the corresponding part of the upper jaw with that on which the Pterodactylus
Sedgwickii was founded, viz., the anterior extremity forming the muzzle (Tab. I,
figs. 1—5), including the first four (a, 4, ¢, @) and part of the fifth (e) sockets of the
teeth. ‘The comparison and appreciation of the specific distinctions of the two
large Pterodactyles are thus rendered easy and satisfactory.

In the specimen of Pterodactylus simus (Tab. I, figs. 1—5), the first tooth (a) on
the left side remains in the socket; it is not larger than the corresponding tooth
in Pterodactylus Sedgwickii, and, consequently, is relatively much smaller than in
that species. Its socket and that of its fellow, moreover, are differently situated,
opening downwards, like the succeeding sockets, and the position of the exserted
foremost tooth is accordingly vertical and nearly parallel with the lower half of
the anterior contour of the muzzle. In Pterodactylus Sedgwickii, the sockets of
the first pair of teeth open upon the forepart of the muzzle, and look almost
directly forward,* and their teeth had, consequently, a nearly similar direction ;
the same, viz., which they appear to have had in Pterodactylus suevicus, Qnst.+

The contour of the muzzle in Pterodactylus Sedgwichu rises at first vertically
above these sockets before curving back into the upper part of the skull’s profile,
and gives an obtuse anterior termination to the upper jaw;{ but this character is
much exaggerated in the present specimen (Tab. I, figs. 1 and 3), not only by the
greater relative extent of the vertical part above the front sockets, but by the
greater breadth of that part, which is flattened anteriorly, forming a surface (fig. 3)
of nearly 2 inches’ in length, about 10 lines in breadth below, and contracting
gradually above to a point, where the blunt ridge begins that forms the upper
part of the profile of this portion of the skull. The name proposed for the
species refers to this peculiarly obtuse and flattened forepart of the cranium.
In Pterodactylus Sedgwickii, the upper ridge of the forepart of the cranium
is continued down to between the first pair of sockets,§ the muzzle being only
obtuse vertically, and not transversely, as in Péerodactylus simus.

The flattened anterior surface, in the specimen figured (Tab. I, fig. 3), is im-

* € Monograph’ for 1857, tab. i, fig 1, c.
+ ‘Ueber Pterodactylus suevicus, &c., 4to, 1855, tab. i.
t ‘Monograph’ for 1857, p. 2, tab. i, fig. 1.

§ Ib., tab. i, fig. 2.

CRETACEOUS FORMATIONS. 3

pressed by a very shallow and wide, longitudinal or vertical channel; but this is
scarcely marked in a second specimen of a muzzle of the same species. In both
specimens the outer surface of the flattened part is less smooth than at the sides
of the muzzle, being impressed by numerous irregular, linear grooves, seemingly
vascular, affecting the vertical direction at the upper part, and the transverse
direction at the rest of the surface.

The ridge where the two sides of the muzzle meet, above and beyond the
flattened surface, is more obtuse and is relatively thicker than in Plerodactylus
Sedgwicku. Were the same curve to be continued from the part of the ridge
preserved until it became horizontal, the vertical diameter of the skull at this part
would be not less than three inches; it may, however, have risen to a greater
height, for the contour is not regularly curved, but sub-angular, as shown
in figs. 1 and 2.

The facial part of the skull must have been narrow in proportion to its height,
and, no doubt, also to its length. ‘The broadest part of the present fragment does
not exceed one inch and a quarter at the fourth pair of sockets; the adherent
matrix (m, m, figs. 4and 5) gives a seeming greater breadth to this part of the skull.

The seckets of the first pair of teeth (a) are three lines apart, the interspace
equalling the largest diameter of the socket; the bone forming this anterior
termination of the palate projects as a convexity below the level of the
alveolar openings, the plane of which is a little inclined outwards. ‘This incli-
nation is increased in those of the second pair of sockets, which are nearly double
the size of the first, and are five lines apart. The second is separated from the
first socket by an interval of two lines; its outlet has a full, ovalform. The third
socket is four lines distant from the second, and exhibits the same ratio of
increase of size; there is a shallow, vertical depression on the outer alveolar wall,
between the second and third tooth, the socket of the latter appearing to have made
a slight prominence on that part of the jaw. The palate at the interspace between
the second and third pairs of sockets is flat, showing no trace of the median ridge
characterising that part of the upper jaw, or of the groove at the corresponding
part of the lower jaw, in the Plerodactylus Sedgwickit.

The upper jaw of the Pterodactylus simus, in the present specimen, has been
partially fractured across the third pair of sockets (figs. 1, 2, 5,c), of which
only the forepart of the left one is here preserved, showing well-marked
vascular grooves. Its outlet, from this fracture, appears to be of a larger oval
or ellipse than in the second socket.

The fourth socket (a) is preserved only on the right side, with about the right
half of the corresponding part of the bony palate. The outlet of this socket
resembles in shape and size that of the second; it is three lines distant from the
third socket.

4 FOSSIL REPTILIA OF THE

The fifth socket (¢), the forepart of which is preserved on the right side,
is four lines distant from the fourth.

The thinness of the compact outer wall of this fragment of the upper jaw, and
the large size of the cancelli, concur with the dental characters in demonstrating
the Pterosaurian nature of the fossil. So far as the outer wall is preserved,
it shows no trace of the external nostril at a distance, viz., of three inches from
the forepart of the upper jaw.

The tooth in place is sub-compressed, conical, long, and slightly curved, with
the convexity forward. The portion of enamel preserved on the crown accords
with the Pterosaurian type of tooth in its thinness, in the very delicate, irregularly
wavy, sometimes branching, longitudinal ridges, on its outer surface; the dentine
is compact, and is coated by cement at the base of the tooth,

Preropactytus Woopwarpi. ‘Tab. II, figs. 3, a, 6, ¢.

The specimen from Professor Sedgwick’s collection, represented of the natural
size in Tab. II, fig. 3, a, 4, is a transverse fragment of the jaw of a Pterodactyle,
from the Upper Green-sand of Cambridgeshire, showing a greater divergence of
the side walls towards the alveolar or oral surface, and, consequently, greater
breadth of that surface in proportion to the height or vertical extent of the
part. Of the oral surface too small a portion is preserved to indicate whether it
be palatal or mandibular. By the characters of the median ridge or groove
pointed out in my former monograph, I incline to regard it as part of the
upper jaw, corresponding in the proportions of height and palatal breadth with
that of the Pterodactylus Fittoni (Tab. I, fig. 3, c, ‘Monograph’ for 1857), but
coming from a part of the jaw further from the anterior extremity.

The fractured ends show the characteristic thinness of the compact, bony wall,
and the large (air-?) cells occupying its substance.

The side wall, which is most entire, has been abraded (Tab. IL, fig. 3, 2), but
the small portions of the preserved surface exhibit the smooth character of
Pterosaurian bone. The fragment includes a pair of sockets, with the bases of
their teeth. The latter show the usual elliptical, transverse section (fig. 3, c).
The implanted base of the tooth extends three fourths of the way to the upper
border of the jaw; it has a coat of cement half a line thick, with the outer surface
longitudinally ridged, corresponding with the grooves of the socket. The
direction of the socket shows that the tooth extended obliquely forwards and
outwards as well as downwards.

Tab. IV, fig. 4, shows the part of the base and basal half of the crown of a tooth
of a Pterodactyle, from the Upper Green-sand of Cambridgeshire, a little sur-
passing in size that of which the hase is shown implanted in the socket of the

CRETACEOUS FORMATIONS. 5

portion of jaw (Tab. II, fig. 3), and of that figured in Tab. I, fig. 6, a, 4, c, of
my former ‘Supplement’ (1857), The total length of the tooth (fig. 4) cannot
have been less than 4 inches.

If the present fragment has belonged to an individual of the same species
as that on the upper jaw of which the Pterodactylus Fittoni is founded, it shows
such species to have attained more than double the dimensions indicated by
the original specimens figured in Tab. I, figs. 3 and 4, of the ‘Monograph’ for
1857. Should the present fragment prove to belong to a distinct species, with the
sides of the jaw meeting above, at a less acute angle, and with the wall of the
outlet of the socket less prominent externally, such species may be indicated
as the Pterodactylus Woodwardi, in honour of the founder of the Geological
Collection of the University of Cambridge.

The mandible (Tab. I, figs. 6—10).

The portion of the right ramus of a lower jaw, or mandible, figured in the
above-cited plate, may have belonged, by its size, to either of the gigantic
Pterodactyles above specified as Pt. simus and Pt. Woodwardi. Its texture and
configuration show it to have formed part of a Pterosaurian skeleton. It is
the part of the ramus which answers to the angular, sur-angular, and articular
elements in the Péerodactylus suevicus,* but with only a part of the sutures
between the angular and sur-angular remaining on the inner side of the bone.
The angle is partially fractured, but seems to have been not much produced
beyond the articular concavity.

The ramus, as it extends forward from the articular part, at first diminishes
slightly in breadth and depth, then increases in vertical, whilst continuing
to decrease in transverse, extent.

The outer surface (fig. 7) presents, near the articular cavity, a shallow,
longitudinal depression, bounded below by a rather sharp border; a broader and
more shallow depression, the lower boundary of which is well defined, marks the
more advanced part of the ramus. These depressions indicate the insertions
of muscles.

Both the upper (fig. 9) and lower (fig. 8) borders are obtusely rounded,
the latter being the thickest. Along the inner side of the fragment a longitudinal
channel (fig. 6, e) extends near the lower border, the upper boundary of the
channel being produced inwards, especially posteriorly (4); above this boundary
there is a deep, longitudinal depression (@) partly filled with matrix, and probably
communicating with the (pneumatic ?) cavity of this part of the jaw-bone.

* Quenstedt, ‘Ueber Pterodactylus suevicus, 4to, 1855, tab. i, figs. 2, 4, 5.

6 FOSSIL REPTILIA OF THE

The longitudinal depression (fig. 6, 2) is bounded below by the angular
element, or part answering to that marked 2 in Péterodactylus suevicus, and
above by the sur-angular (c). This element appears to have coalesced with the
articular one; but between the bone (a, c) and that marked % a true harmonia or
toothless suture remains. The line below the letter e¢, in fig. 6, appears to be an
accidental crack. The fractured anterior end of the fragment (fig. 10) indicates
the extreme thinness of the wall of the bone, which consists of compact osseous
substance. A part of the concave, articular, surface is shown at a, fig. 7.

A similar longitudinal depression on the inner side of the back part of the
ramus, with its lower boundary produced as a ridge, and formed by the angular
element (2), is indicated in the figure of the lower jaw of the Péerodactylus
suevicus in Professor Quenstedt’s memoir; according to the proportions of
which jaw, the present comparatively enormous fragment would answer to almost
the hinder half of that part of the ramus which has not united with its fellow
to form the long symphysis, and it may be estimated as including one fourth of
the entire length of the lower jaw, which would give to the Pterodactyle, yielding
the present mandibular fragment, a head exceeding sixteen inches in length. It
is probable, however, that the head of Plerodactylus simus was relatively
shorter and thicker than in the smaller species of Pterodactyle.

The Basi-occipital (Tab. I, figs. 11, 12, 13).

A skull of the size above indicated would require an occipital condyle at least
as large as that on the basi-occipital element figured in the above-cited plate.
This condyle projects backward on a well-marked base too broad to be called a
peduncle; the convexity is only hemispheric, with the transverse diameter pre-
dominating ; its shape and position indicate great freedom of movement of the
head upon the spine. There is no mark of a sutural surface for the exoccipitals on
the expanded part of the bone (2); they were probably confluent, as in birds, with
the basi-occipital, and have been broken away; the fractured surface (fig. 12, 2)
shows the large cancelli of this part of the occipital bone. The upper surface (a)
indicates a wider foramen magnum, or neural canal, than that of the combined
atlas and axis (fig. 14, x), and such astructure accords with the free and exten-
sive movements of the head upon the spine indicated by the form and promi-
nence of the condyle and its occipital cup (c).

Atlas and Axis (Tab. I, figs. 14, 15, and 16).

The anchylosed atlas and axis (figs. 14, 15, and 16) correspond in size with the
above-described basi-occipital; they were obtained at the same time from the

CRETACEOUS FORMATIONS. 7

same pit of the Upper Green-sand deposit near Cambridge. The condyloid ball
(fig. 12, c) neatly fits the cup ¢ of fig. 14, and most probably belonged to the
same individual. All the characters described and figured in my paper on
the ‘ Vertebree of Pterosauria, * and in a preceding monograph, are repeated
in the present larger specimens of the first and second neck-vertebre. In the
more transverse extension of the posterior articular ball of the axis (fig. 16, 4)
the present specimen agrees with the smaller of the two previously figured
specimens of this part of the vertebral column. {

Cervical Vertebre (Tab. II, figs. 1, 2, and 4).

The middle (fourth or fifth?) cervical vertebra of a Pterodactyle, corresponding
in bulk with that indicated by the fossils above described and figured (Tab. I,
figs. 1—16; Tab. II, fig. 3), agrees in the proportions of length and breadth more
with the smaller vertebre (Tab. II, figs. 14—17, vol. for 1857) than with the
vertebree (ib., figs. 7—11) described in my former monograph of that date. It
shows the same posterior extension of the centrum (fig. 2, 4, p) beyond the neural
arch (n), but with somewhat greater divarication of the hinder processes (p) than
in figs. 18 or 11 of Tab. II of the above-cited monograph. The present specimen
very strikingly illustrates the characteristic breadth and depression of the
centrum of the middle cervicals of the large Green-sand Pterodactyles. The
neural canal (fig. 2, ») appears to be proportionally more contracted than in
the smaller cervical vertebre; it is relatively much smaller than in any bird,
marking well the reptilian nature of the extinct flying air-breather. The anterior
surface of the diapophysial productions of the forepart of the base of the neural
arch is marked by a groove extending from above and within outwards and
downwards. ‘The whole base of the arch has coalesced with the centrum; the
major part, with the neural spine and zygapophyses, has been broken away.

An oblique side view of the last cervical vertebra of a similar-sized Ptero-
dactyle is given in Tab. II, fig. 4, showing the more produced diapophysis (@),
perforated by the vertebrarterial foramen (/), indicative of the development in
this vertebral segment of a rudimental rib, and of its coalescence with the other
elements, the whole extending below the level of the under part of the centrum.
Above and behind this foramen is that for the admission of air into the bone; it
is of a similar size, and of a narrow, elliptical form. The posterior zygapophysis
(z) is now raised to a higher level than the anterior one, indicating the sudden
bend of the neck at this part. The posterior processes (p) are smaller and less

* - Philosophical Transactions,’ 1859, p. 165, pl. 10, figs. 23—34.

+ ‘ Palzontographical Society,’ vol. for 1857, pp. 7, 8.

{ Compare Tab. I, fig. 16, with Tab. IT, fig. 14, and Tab. IV, fig. 2, of the ‘ Monograph’ of 1857.

8 FOSSIL REPTILIA OF THE

produced; the body of the vertebra is narrower, but deeper, than in the more
advanced vertebra (fig. 1). The posterior zygapophysis is surmounted by a
tubercle.

Caudal Vertebre (Tab. II, figs. 13—16).

The caudal vertebra, from the anterior half of the tail (figs. 13 and 14), presents
a size corresponding with the proportions of the Pterodactyle given by the above-
described neck-vertebre ; the neural arch and zygapophyses continue to be dis-
tinctly developed at this region of the tail. There is a foramen (o), leading into
the substance of the neural arch, on each side of the back part of that arch, and
near the corresponding outlet of the neural canal. In the more distal vertebra
(figs. 15 and 16) the neural arch has sunk, and seems almost blended indistin-
guishably with the centrum, which is much longer than in the vertebre nearer
the trunk. The zygapophyses cease to be developed; but the articular, shallow
cup and ball at the ends of the vertebra show that the tail retained its
mobility, and was not stiffened or anchylosed as at the corresponding part in
Ramphorhynchus.

The Sternum (Tab. IT, figs. 7—12).

According to the very able and instructive summary, by M. V. Meyer, of the
osteology of the best-preserved examples of the skeletons of Pterodactyles, those,
viz., from the lithographic slates of the Jurassic (Mid-oolitic) series of rocks, the
sternum is a compound bone, consisting chiefly of a symmetrical, keelless, broad
plate,* having an anterior process answering to the episternal process in the
crocodile,t and with distinct side parts, having articulations for a few bony,
sternal ribs.t As to its resemblance, otherwise, to the sternum of raammals, birds
or reptiles, in regard to the articular surfaces for the scapular arch, nothing has
been, hitherto, determined.

* «Tas Brustbein ist ein schwach gewodlbtes knochernes Schild, das breiter als lang, und daher eher
dem Briistbein der nur kiimmerlich mit Fiige/n versehenen Strauss-artigen Thiere beider Erdhialften, als
dem in den Flug-begabten Vogeln zu vergleichen ist. Es zeigt keinen Kiel oder Grath, und Maw kénnte
daher glauben, das die Stelle zum Ansatz eines kraftigen Flugmuskels fehlt, die Pterodactyln keine gute
Flieger gewesen waren.” (‘Reptilien aus dem Lithographischen Schiefer,’ fol., 1859, p. 17.)

+ ‘Am Brustbein der Pterodactyln wird ein vorderer Forsatz wahrgenommen, der den Kiel ersetzt und
den Brustmuskeln als Anheftungsstelle gedient haben wird. Dieser Theil erinnert an den Forsatz am
Brustbein des Crocodils.”” (bid., p. 18.)

t “Bei Ramphorhynchus Gemmingi fand ich ausser den gewohnlichen Brustbein nach eine Platte mit
Brustrippe welche die Verbindung mit den Kiickenrippen unterhalten haben werden und wie in den
Vogeln knéchern waren.” (Ibid., p. 18, tab. x, fig. 1.)

CRETACEOUS FORMATIONS. i)

The rich repository of remains of gigantic Pterosauria in the Upper Green-
sands of Cambridgeshire have added valuable evidence on these important points,
and demonstrate a nearer approach to the keeled character of the breast-bone of
flying birds than the specimens of the smaller species described in the under-
cited works appear to demonstrate. By the kindness of Professor Sedgwick, 1
am enabled to compare the specimens of portions of the sternum acquired by the
Woodwardian Museum with that which has recently been purchased by the
British Museum. The best of these specimens consist of little more than the
thicker and stronger, contracted forepart of the breast-bone (Tab. II, figs. 7, 8,
and 9), broken away from the thin, expanded, fragile plate (4), of which it princi-
pally consists, and of which remains or impressions have been preserved in a few
slabs of fine-grained stone of the Oolitic series, such as the lithographic slate ;
that of Péerodactylus suevicus* showing the posterior border of the symme-
trical plate to be convex and entire, not notched or perforated, as in many birds.
The forepart of the sternum of the gigantic Pterodactyle from the Cambridge
Green-sand includes the major part of the anterior process, and also the pair of
articular facets for the coracoids. The keel-like process in the specimen
(Tab. IT, figs. 7, 8,9, 6, e, f) is continued forward from that articular region (¢, ¢), for
an extent equal to the depth of the bone at the same part; but the process is not
entire. lis base is gently convex at the sides, from the middle and thickest part
of which it gradually narrows to a ridge, of about a line or less in thickness at
both the upper and under margins; the extreme forepart being broken away,
prevents the determination of the precise extent or contour of that end, but
the convergence of the preserved parts of the upper and under margins
indicate a convexly rounded termination (fig. 7,¢). There is a gentle de-
pression on each side of the beginning of the upper part of the ridge, which ridge
is continued from a thickening or tubercle (figs. 7, 8, 4), bounding anteriorly a
small, deep, transversely oval depression (@) between the two articular surfaces
for the coracoids (¢). This tubercle answers to what I have termed the “ manubrial
process” in the sternum of birds,{/ and the above pre-coracoid part of the
sternum answers to that process, confluent below, as in Aptenodytes, with the
produced “keel.” This, however, in Pterodactylus,. quickly loses depth as it
extends backwards along the mid-line of the under part of the sternum, some way
behind the articular region, and has not quite subsided at the forepart of the
expanded body of the breast-bone (fig. 9, ¢), from which the rest of the shield-like
plate has been broken away. The sides of the post-coracoid part of the keel are
gently concave; the lower border of the keel is first convex, then concave to near
its posterior termination, both in a very feeble degree (fig. 7, ¢, /). Each of the

* Quenstedt, ‘Ueber Pterodactylus suevicus, im Lithographischen Schiefer Wiirtembergs,’ 4to, 1855.

+ Art. “Aves,” ‘Cyclopedia of Anatomy and Physiology,’ vol. i, 1836, p. 282, fig. 129.
9

10 FOSSIL REPTILIA OF THE

articular surfaces for the coracoid (figs. 7 and 8, c, d) is sub-triangular, convex
transversely, concave in the opposite direction, with the lower angle continued
down upon the side of the thickest part of this anterior portion of the sternum.
The back part of the articular surface rises higher than the front, so that the
general aspect of the surface is obliquely upward, forward, and outward. The
two surfaces are separated by a non-articular depression (qd), of the breadth of one
coracoid surface; this depression is bounded, like the sella turcica of the human
sphenoid, by a transverse rising or ridge of bone (fig. 7, a), continued between the
hinder angles of the two articular surfaces, and in front by the manubrial tubercle
(4), from which the upper border of the produced keel is continued. The ster-
num contracts behind the articular region at yg, figs. 8 and 9, and then expands
rapidly in the horizontal direction, to form the broad, lamelliform body of the
bone (4), which, in Pterodactylus suevicus,* appears to have been ,almost semi-
circular in shape, and to have extended backward beneath about one half of the
thoracic abdominal cavity. The upper surface of the forepart of the sternal plate is
concave, and it becomes flatter as it expands. The lateral and lower surfaces are
also concave vertically, with linear markings, showing the implantation of the pec-
toral muscles that filled those concavities on each side the keel. Sufficient thickness
of the bone remains at the fractured posterior part (/), where the keel has not sub-
sided, to show the widely cancellous, and seemingly pneumatic, texture of the bone.

The similar, but smaller and more mutilated, portion of a sternum of a Ptero-
dactyle (Tab. II, figs. 10—12) shows the same form and position of the cora-
coid articular surfaces, the non-articular intermediate depression, the lateral
emarginations or contraction of the sternum behind the part supporting the cora-
coids, and the backward extension of the keel beneath a certain proportion of the
expanded body of the sternum, forming the hollows for the lodgement of the
pectoral muscles.

A sternum of the shape and proportions above described plainly indicates
pectoral muscles of great bulk and strength, by the extent of origin it afforded to
them, and by the depth of the depressions they filled on each side of the keel;
but to what purpose the limbs moved by those muscles were put is best inferred
from the characters of the bone into which they were inserted. If, however, the
peculiar development of the fore limbs of the Pterodactyle had not been known,
the evidence of a pneumatic or widely cancellous structure in the thicker forepart
of the breast-bone would have suggested a power of locomotion in its original pos-
sessor akin to that of the class to the sternum of which that of the Pterodactyle
makes, upon the whole, the nearest approach.

It is true that the sternum is broad and shield-shaped in the Apteryx and
other land-birds devoid of the power of flight; but this form, together with the

* Quenstedt, op. cit.

CRETACEOUS FORMATIONS. 11

strong coracoids and their articulation with the sternum, relates, in them, to the
mechanism of respiration. The ossified sternal ribs, with their articulations to
the sides of a broad sternum, indicate a like function of the breast-bone in the
Pterodactyle, viz., to expand the thoracic abdominal cavity, when such plate of
bone, with attached but jointed sternal ribs, was pressed down by the coracoids.*
The superadded keel, co-extended anteriorly with the connate manubrial pro-
cess of the sternum of the Pterodactyle, plainly bepeaks, however, additional
functions; but these might have been, as M. Von Meyer suggests, the same as
in the penguin, or even in the mole. And, at this point, the physiologist
in quest of the locomotive relations of the sternum, would pass to the
comparison of the humerus and other bones of the fore limb; or, failing
those, to a more minute scrutiny of the texture of the breast-bone of the
Pterodactyle. It is almost superfluous to remark that the evidence of the
fore limbs had shown the Pterodactyle to have been a flying animal long before
anything was precisely known as to its sternum.

The development of the interpectoral process or keel of the sternum in
the Pterodactyle exceeds that in any of the bat tribe; and it may be confidently
concluded that the flight of the winged reptile might have been, at least, as swift
and of as long continuance as in the Péeropi. But, viewing the pneumaticity of
the bones of the Pterodactyle, and the relatively greater and more continuous
development of the interpectoral crest of its sternum, I am led to believe it
to have been a creature of more extensive, continuous, and powerful flight than is
now enjoyed by any bat ; and the Pterodactyles may at least have been as capable
of migration as the great frugivorous Chiroptera. ‘The structural affinities,
however, of the Pterodactyles to the cold-blooded air-breathers, and their analogy,
in wing-structure, to the bats, indicate that they might have possessed the faculty
of becoming torpid, and of so existing during a period when their food in a given
locality was not attainable.t+

* From the appearances presented by the crushed specimen of Péterodactylus Gemmingi, imbedded in a
slab of lithographic slate, I believe that the part of the sternum showing those articulations has been
accidentally separated from the rest of the fractured bone. (See Von Meyer, Tab. x, op. cit.) The estimable
author concludes that the marginal portion of sternum, with articulations with ossified sternal ribs, was
originally distinct from the body or main plate of the sternum: but the plate of the specimen he describes
shows fractures and some mutilation of the bones.

+ The inferences from what was previously known as to the structure of the sternum of the Ptero-
dactyle are thus expressed by M. H. v. Meyer, in his summary of the knowledge of the Pterosauria, in
1859: ‘* Hs zeigt keinen Kiel oder Grathe, und man kénnte daher glauben, dass, da die Stelle zum Ansatz
eines kraftigen Flugmuskels fehit, die Pterodactyln keine guten Flieger gewesen waren. In dem Mangel
eines Kieles scheint indess nur eine Andeutung zu liegen, dass die Thiere keine Vogel waren. Eben so
wenig werden sie Wanderthiere gewesen seyn, und bedurften daher auch keines so starken Brustmuskels.
Das Brustbein der Fledermiiuse gleicht sogar durch die Gegenwart eines Kiels mehr dem in den Vogeln

12 FOSSIL REPTILIA OF THE

In no other reptile does the sternum present coracoid articulations so shaped
and so placed as in the Pterodactyle. The Crocodilia, in which, as in Pterosauria,
the clavicles are wanting, show the broad, sternal margins of the coracoids
ligamentarily attached to the middle of the lateral border of the sternum.

Tn bats the obtuse, sternal ends of the clavicles are applied to protuberances of
the manubrium above the articulations of the first pair of ribs. Only in birds are
distinct synovial articular cavities provided for the coracoids, which, in the main,
are situated and shaped as in the Pterodactyle. The differences are these: the
concavity and the convexity being (as, e. g, in Aptenodytes), the same, the bent
grooves so formed are much longer than in the Pterodactyle, with a concomitant
greater expansion of the ends of the bones they firmly lodge. The coracoid
grooves are divided by a non-articular, median depression in Aptenodytes, but
this, in some other birds, is wanting, the coracoid grooves decussating across the
middle line, e. g., in the Heron.* There are various minor modifications of the
coracoid grooves in the breast-bone of birds.

The marked distinction in the breast-bone of the Pterodactyle is its com-
pression behind the coracoid articulations, and the distinct commencement of the
shield-like expansion behind that articular part.

In most birds the “‘manubrium’” projects from the mid-space between the
coracoid grooves, and is distinct from the “keel;” in some it is bifurcate; in the
penguins it is as little developed as in the Pterodactyle, and is as directly
continuous or connate with the forward production of the keel. In this
production Aptenodytes patachonica most resembles, amongst birds, the
Pterodactyle. The parts are homologous, and if we name that production
the forepart of the keel of the breast-bone in the aquatic bird, we must apply
the same name to it in the Pterodactyle; only in the latter the keel subsides
sooner beneath the expanded part of the sternum.

In the Crocodilia the broad, thin, sternal borders of the coracoids are attached
by fibrous substance to the fibro-cartilaginous, or, in old animals, partially

Es besitzen aber auch die Maulwiirfe am brustbein diesen Kiel, der daher nicht unbedingt als ein Zeichen
des Flugvermogens gelten kann; er setzt eigentlich nur starke Brustmuskeln voraus, die daran befestigt
waren. Selbst in den Schwimmyvogeln die nicht zu fliegen vermégen ist der Kiel vorhanden fir starke
Brustmuskeln, die hier zum Schwimmen eben so nothig sind wie dem Maulwiirf zum Graben. §
Aus diesen Betrachtungen ergiebt sich, dass der Pterodactylus nach der Beschaffenheit seines Brustbeins
weder ein eigentliches Wasserthier, noch ein Graber war, vielmehr ein Thier der Luft.” (‘ Reptilien aus
dem Lithographischen Schiefer,’ &c., fol., p. 17.)

Professor Quenstedt, however, seems to me to have rightly appreciated the homology of the forepart of
the sternum and the physiological deductions from it: ‘‘Der Kamm spriygt vorn einen halben Zoll weit
iiber die Fliche des Knochens hinaus, gibt daher Beweis genug, das das Thier fliegen konnte.” (Op. cit.,

p. 44.)
* «History of British Fossil Mammals and Birds,’ 8vo, 1846, p. 556, fig. 236.

CRETACEOUS FORMATIONS. 13

ossified, plate, representing the sternum of struthious birds. The bony sternum,
or “episternum,” is long, narrow, and depressed; it is considerably produced
in advance of the coracoids, but this produced part is flattened horizontally.
If it be compared with the pre-coracoid part of the sternum in the Pterodactyle
or penguin, it is not more like the one than the other. In the main, the
Pterosaurian breast-bone, like the scapular-arch, is formed on the ornithic type,
but the post-coracoid, lateral emarginations are distinctive Pterosaurian characters.

The Humerus of Pterodactylus (Tab. ILI).

The fragile texture of the bones of the Pterodactyle, and the consequently
crushed or broken state in which those of the wings more especially have hitherto
been usually found, have precluded any precise description or figures of the
articular surfaces, or of the configuration of the extremities of these bones.
And yet such particulars are absolutely requisite for defining the resemblance
of the Pterosaurian humerus to that of the bird and reptile, and for acquiring
this element in the determination of the degree of affinity or relation of the
Pterosauria to those classes respectively.

The remains of the very large species of Pterodactyle from the Cretaceous
formations of Kent and Cambridgeshire have furnished materials for advancing
this desirable knowledge in regard to the structure of the vertebre,* and I have
now similar means of contributing more precise information respecting the
structure of the proximal end of the humerus than has hitherto been possessed.
For the subjects of this study and comparison I am chiefly indebted to Professor
Sedgwick. But, in proceeding to impart the results, [ must premise some notice
of the character of the humerus in birds, in which I shall avail myself of the
terms indicative of aspect and position proposed by Dr. Barclay, in his
‘Anatomical Nomenclature.’

Proximal signifies the upper, distal the lower, ends of the bone, as it hangs in
man; anconal is the posterior, palmar the anterior, surface, as when the palm
of the hand is directed forward; radial is the outer, ulnar is the inner, side,
according to the same position of the human arm and hand. Prowimad, palmad,
&c., are adverbial inflections, meaning towards the proximal (upper) end, and
towards the palmar (anterior) side.

In the bird, then, the humerus has a smooth shaft, sub-elliptic in transverse
section, with expanded ends, the proximal one being the broadest. Lengthwise
the bone is gently sigmoid, the proximal half being convex palmad, the distal half

* Phil. Trans., tom. cit.

14 FOSSIL REPTILIA OF THE

concave, with the plane of the terminal expansions vertical, as the bone extends
alcng the side of the trunk from its scapulo-coracoid articulation backward, in its
position of rest.

The head of the humerus is an elongate, semi-oval convexity (Tab. III, fig. 8 a),

with the long axis transverse from the radial to the ulnar sides (vertical, as naturally
articulated), and with the ends continued into the upper (4) and lower (c) crests.
Of these, the upper one (4, figs. 6—8), in the natural position of the bene, is on
the same side as the radius, the lower, more tuberous one (c), is on the same side
as the ulna; the one marks the “radial” side, the other the “ulnar” side, of the
bone. The side of the humerus next the trunk answers to that called “ anconal”
(fig. 7), the opposite side to that called “ palmar” (fig. 6).

The expanded, proximal part of the shaft on the palmar side (fig. 6) is concave
across, convex lengthwise ; on the anconal side (fig. 7) it is convex across to
where the ulnar ridge (¢) bends anconad near the pneumatic orifice (p). f

The radial crest (4) answers to the “ greater tuberosity ” and to the “ pectoral”
and ‘“deltoidal ridges” in mammals; the “ulnar” crest (c) to the “lesser tube-
rosity,’ and the ridge for the “latissimus dorsi,” in mammals.

In a few exceptions the shaft of the humerus is almost cylindrical, in still
fewer (e. g., Aptenodytes) it is flat.

In the vulture (V. monachus), the ulnar crest forms a thick tuberosity at its
proximal end (fig. 7, c), projecting anconad, and overarching the “pneumatic”
foramen (p); it descends a short way obliquely palmad, decreasing in breadth,
but still thick, convex, and terminating obtusely (fig. 6, c’). The radial crest
(fig. 6, 4) better merits the name; it extends twice the length of the ulnar one,
down the shaft, to the palmar side, towards which the whole crest is slightly bent ;
its margin describes a very open or low, obtuse, angle at its middle part. A
ridge (r) upon the palmar side of its distal half indicates the boundary of the
insertion of the pectoralis major into the crest. At the middle of the anconal
surface of the proximal part of the shaft there is a low, longitudinal
ridge (J).

At the distal part of the humerus a ridge on the radial side of the palmar
surface, and a rising of the bone on the ulnar side of the same surface, diverge
to the opposite angles or tuberosities of the expanded end of the bone; they
include a shallow, sub-triangular concavity above the articular surfaces. ‘These
are two, and are convex.

The radial surface is a narrow, sub-elongate convexity, extending from near
the middle of the palmar surface obliquely to the lower part of the radial
tuberosity, where the convexity subsides; it is very prominent at its palmar end,
with a groove on each side, the deeper one dividing it from the ulnar, articular
convexity. This is of a transversely oval or elliptical shape, most prominent

CRETACEOUS FORMATIONS. 15

paimad; all the part of the end of the humerus forming the two articular
convexities is as if bent toward the palmar aspect. The ulnar end of the ulnar
convexity is bent, and continued anconad to that end of the ulnar tuberosity.
An oblique, longitudinal channel divides the anconal end of the radial tuberosity
from an almost longitudinal ridge, which is nearer the middle of the anconal side
of the distal end of the humerus; a similar, but shorter, longitudinal ridge or
rising of bone, terminates in the anconal part of the ulnar tuberosity. Between
the above almost parallel ridges the anconal surface is nearly flat transversely ;
it is traversed along the middle by a low, narrow, longitudinal ridge. Lengthwise
the bone is here convex.

The differences in the humerus of different birds are seen chiefly in the forms
and proportions of the proximal crests; the radial one in the Columbide, e. g., is
shorter and more produced than in most birds of flight. The humerus in the
swift and humming-bird is distinguished by special modifications.

In the crocodile (Tab. III, figs. 9—12), the articular head of the humerus
(fig. 12, a) is a transversely elongated, sub-oval convexity; it is continued upon
the short, obtuse, angular prominence (c), answering to the ulnar crest or tuberosity
in the bird. The radial crest (fig. 9,2) begins to project from the shaft at some
distance from the head of the bone; it is shorter, thicker, more prominent,
and projects more directly palmad than in the bird. The humerus presents a
similar sigmoid flexure lengthwise to that in the bird, but the ulnar contour
of the shaft, as it descends from the ulnar end of the head of the bone, describes
a concave line to the ulnar condyle; the radial contour is sigmoid, and not
affected by the radial crest, as in the bird. There is a longitudinal ridge
(fig. 10, @) on the anconal surface close to the radial border.

The humerus of the Pterodactyle (ib., figs. 1—5) is shorter in proportion to
the expanse of its proximal end than in either the bird or crocodile, and it
appears to have a straighter shaft. It conforms at its proximal end more with
the Crocodilian than the Avian type. The ulnar crest, or tuberosity (c), is rather
more prominent and better defined than in the crocodile, but the radial crest (2) is
much more developed than in either the crocodile or bird. It resembles that
of the crocodile in being more directly bent palmad, or what would be outward in
relation to the side of the trunk, in the natural position of the bone at rest.

The crest begins, above, at the radial and palmar end or angle of the articular
head of the bone, and rapidly expands, bending palmad, with a base co-extensive
with one fifth of the length of the humerus, inclining, as it descends (fig. 3), to the
palmar side, and ending below by a rough tuberosity projecting at aright angle from
the shaft of the bone; the lower sharp margin (fig. 1, ’) of the tuberosity passes by
a quick curve, and subsides upon the cylindrical shaft. The palmar surface of the
proximal part of the humerus, by the production in that direction of the ulnar

16 FOSSIL REPTILIA OF THE

tuberosity, but more especially by the direction of the large, radial crest (4), is
more concave across than in birds. Between 4 and ce, g, in fig. 1, it is gently
convex lengthwise, and is very smooth.

A longitudinal ridge (fig. 1, -), along the distal half and palmar side of the
base of the radial crest, indicates, as in birds, the insertion of the strong and large
pectoral muscle. |

The articular. head of the bone is reniform, not uniformly convex, as in birds,
but slightly concave between the beginnings of the radial and ulnar crests or
processes on that moiety of the head next the palmar side (fig. 3, a). At the
opposite (anconal) side (fig. 2, a), the head projects slightly beyond or overhangs
the shaft, the upper part of which, on the anconal side, is slightly concave
lengthwise, very convex across, more so than in birds, and without trace of
the median longitudinal ridge (, fig. 7). It is equally devoid of the ridge
which, in the crocodile (fig. 18, d), runs close to the radial side of the anconal
surface.

The shaft is more cylindrical than in birds. The pneumatic foramen (figs.
3, 5, p) is situated a little below the radial end of the head of the bone, on
the palmar side of the bone; in the vulture, and most birds of flight, it is situated
on the opposite side (fig. 7, »). The pneumatic texture of the shaft is as
well marked as in any bird of flight.

Tn looking directly upon the palmar side of the humerus in the bird one has
an oblique, foreshortened view of the radial crest, the base of which lies wholly
along the radial margin. Taking the same view of the humerus of the Ptero-
dactyle as in Tab. III, fig. 3, we look almost directly upon the edge of the
radial crest (é, 0’), the base of which has inclined below from the radial upon the
palmar surface. A corresponding view of the humerus of the crocodile (fig. 11)
shows the whole base of the radial crest on the palmar surface, clear of the
radial border, and the opposite side of the crest to that in the bird is obliquely
brought into view. (In the figure 11 the radial side of the shaft is rather too
much turned towards the eye.)

In the position and shape of the radial crest the Pterodactyle is between the
bird and the crocodile; in the transverse extent of the crest it exceeds both. The
crest differs in extent and shape in different species of the Pterodactyle. In fig. 1
the ulnar side of the shaft is turned so far towards the eye as to permit the whole
breadth of the radial crest (4) to be seen. ‘The degree to which the radial crest
projected in the humerus of the large Cretaceous Pterodactyle (Tab. III, fig. 1)
is only shown at its lower part, the upper, thinner portion being broken away.
Relatively to the size of the head of the bone, the extent of the base is greater
than in the smaller species of Pterodactyle, a corresponding portion of the
humerus of which is represented in fig. 5, from the same aspect as fig. 1. The

CRETACEOUS FORMATIONS. 17

extent of the base of the radial crest in fig. 5 corresponds with that of
Pterodactylus suevicus.*

In Ramphorhynchus Gemmingi the radial crest, with a similar short origin,
has a remarkable transverse extent, and expands at its termination, so that
both upper and lower margins are very concave.t The latter is of much greater
relative extent than in the large Cretaceous Pterodactyle (Tab. III, fig. 1). The
Wealden Pterodactyle (Pter. ornis) resembled Ramphorhynchus in the propor-
tions of the radial or outer process (g, fig. 5, ‘Quart. Journal of the Geol. Soc.,
1845, p. 99).

The determination of the homologies of the processes from the proximal end
of the humerus of the Pterodactyle with those in the bird and crocodile enables
one to recognise the specimen (figs. 1—3 and fig. 5) as part of the right
humerus.

Fig. 4 is part of the left humerus, from the Upper Green-sand of Cambridge-
shire, but was drawn upon the stone without reversing, to facilitate its comparison
with fig. 1, from the Middle or White Chalk of Kent, which it resembles in the
extent of origin of the radial ridge (6).

Carpal Bones (Tab. II, fig. 6; Tab. IV, figs. 5—9).

The two bones (Tab. IV, figs. 5, 6, and figs. 7—10) correspond in size so
much more with that of the distal extremities of the radius and ulna than with that
of the same part of the tibia, as to leave a conviction that they are carpal bones,
and they afford instructive evidence of the characters of those bones in the
Pterodactyle. Specimens of more or less entire, but dislocated, skeletons of the
smaller kinds of Pterodactyle from Oolitic strata, especially that of Péero-
dactylus suevicus from the lithographic slates of Wirtemburg,t and that of
Ramphorhynchus Gemmingi from the same formation at Eichstadt,§ have demon-
strated the presence of at least two large carpal bones, with one or two smaller
ones, the two carpals forming a first and second row; but the figures are too small
and indefinite to permit the matching with them of either of the larger and
probably better-preserved carpal bones from the Cambridge Green-sand.

The first to be described is subdepressed, subtriangular in shape, with a general
tendency to convexity on one articular surface (Tab. IV, fig. 8), and to concavity

* Quenstedt, op. cit., tab. i, ev, el.

+ H. v. Meyer, op. cit., tab. ix. A. Wagner, ‘Fauna des Lithogr. Schiefers,’ 4to, 1858, taf. xvi.

t Well described and figured by Professor Quenstedt, in his treatise ‘Ueber Pterodactylus suevicus,’
Ato, Tubingen, 1855.

§ H. v. Meyer, op. cit., tab. ix, fig. 1.

18 FOSSIL REPTILIA OF THE

on the opposite surface (fig. 7); but both these surfaces are irregularly undulated,
as shown inthe figures; the more concave surface being also impressed by a deep
hemispheric pit. I conjecture that this bone formed the proximal part of the
carpus, and that the pit may have received a process of the distal end of one of
the antibrachial bones. ‘The opposite, probably distal, and more convex surface
(fig. 8) is divided into two slight convexities, by a shallow, wide channel, crossing
the bone obliquely. The convexity (a) meets the concave surface on the other side
of the bone (¢,/) by their convergence to the basal border or margin, which presents
a slight notch. ‘The opposite end of the bone forms the obtuse apex (d), which
is a little bent down towards the concave side. On this side (fig. 7) the notch is
continuedinto an angular channel, which divides the two shallow, concave sur-
faces (e and f) occupying the basal half of this surface; a little nearer the apex
than the middle of the bone comes the hemispheric pit, with a small depression
on one side of it.

Fig. 9 shows the thickest or deepest, non-articular side of the bone, sloping to
the end of the facet (f), and with the apical tuberosity (a) at the opposite end.

Fig. 10 is taken looking upon the convex surface from the notched
base (a).

Fig. 8 may correspond with the surface of the carpal bone in Péerodactylus
suevicus, marked 1, in the bones of the left wing in Professor Quenstedt’s Plate ;
and the side view of the same bone in the carpus of the right wing gives an
indication of the produced apex. ‘The outline of the large proximal carpal in
Pierodactylus (Ramphorhynchus) Gemmingi, in M. v. Meyer’s Plate, accords
in a general way with the profile of the narrower side of the present bone,
which, for the convenience of indication and description, might be called the
““scapho-cuneiform.” I have no proof, however, from knowledge of its precise
connexions, of the accuracy of this determination; but strongly suspect that the
bone may represent more than one of the proximal carpals in the mammalian
wrist, and probably the two proximal bones in the carpus of the crocodile.

In Tab. II, fig. 6, a scapho-cuneiform bone is figured, which, from its size,
might belong to Péerodactylus simus; it differs from that in Tab. IV, fig. 7,
not merely in size, but, apparently, in a greater relative breadth of the surfaces
(e and f); their margins forming the base of the triangle have been, however,
abraded.

The second large wrist-bone (Tab. IV, figs. 5 and 6), if the foregoing be rightly
compared, will match with the carpal bone articulating with the proximal end of
the metacarpal of the fifth or wing-finger in the plates of Pterodactylus suevicus,
and of Ramphorhynchus Gemmingi, above cited; and it will consequently
answer to or include the “ unciforme,’ by which name it will be here described
and figured.

CRETACEOUS FORMATIONS. 19

Both proximal and distal surfaces show well-defined, concave articulations.
On the more concave surface (fig. 5) there is an oblong, articular depression (y),
continuous at the margin (4) with a surface on the opposite side of the bone;
a more irregular undulated channel, deepest at the middle part (i), occupies the
rest of the surface, but the end of the bone opposite (4) has been broken away.
Fig. 6 shows two shallow, articular channels (% and 1), partly divided near the
end (4) by a tract of non-articular surface.

In birds the base of the metacarpal of the digitus medius has. the “os
magnum” connate therewith, it also becomes confluent with the bases of the
second and fourth metacarpals. Between this compound bone and the anti-
brachium two distinct carpal bones partially intervene, being wedged between the
metacarpus and antibrachium, one on each side. The Pterodactyle, in the com-
plete separation of the metacarpus from the antibrachium, by two successive
carpals, answering to the two rows, adheres more closely to the Reptilian type;
but differs in the much greater expanse and complexity of the carpals, and in
their minor length.

Ungual Phalanz (Tab. IV, figs. 11 and 12).

The ungual phalanx (Tab. IV, figs. 11 and 12), accords in size with that of the
limb indicated by the carpal bones (figs. 5—10). The articular surface presents
two trochlear concavities, extended vertically, narrow transversely, divided by a
median ridge; the upper angle is rather produced; below the trochlea is a
smal] depression, and below this the bone projects in the form of the rough pro-
tuberance for the flexor tendon. On each side of the phalanx is the curved
vascular groove, beneath which, in some specimens, the bone slightly expands.
In one specimen a second, more shallow groove is shewn on one side, nearer the
upper margin of the bone.

20 FOSSIL REPTILIA OF THE

Orver—SAUROPTERYGIA, Owen.*

Genus—PouyPtTycHopon, Owen.

PoLYPTYCHODON INTERRUPTUS, Owen.

In the ‘Monograph of the Fossil Reptilia of the Chalk Formations,’ p. 200,+
certain dental and osteological characters of a large extinct Saurian were described
and figured, confirmatory of the distinct generic form of reptile, for which had
been proposed the name Polyptychodon,{ having reference to the numerous longi-
tudinal ridges and grooves, giving a minutely folded surface to the enamel cover-
ing the crown of the tooth. In my ‘ Report on British Fossil Reptiles,’ the genus
was referred to the ‘Sauria incertz sedis, no other parts save the teeth being
then (1841) known. A few years later a portion of jaw was discovered in the
Lower Chalk of Kent, showing that the teeth were implanted in distinct sockets,
as in the Crocodilia. This specimen I described and figured in the work of my
friend, Mr. Dixon, entitled ‘The Geology and Fossils of the Tertiary and Cre-
taceous Formations of Sussex.’§

Some large fossil bones from a Green-sand quarry near Hythe, Kent, described
in the above-cited ‘Monograph on the Fossil Reptilia of the Cretaceous Forma-
tion,’|| as probably belonging to Polyptychodon, showed that “the pubis and
ischium approached somewhat to the Plesiosaurian type.”

Cranium and Teeth (Tab. IV, figs. 1—3).

I have lately been favoured by Mr. George Cubitt with the inspection of part
of the cranium, including portions of jaws with teeth, of Polyptychodon
interruptus, discovered in cutting a railway tunnel through the Chalk formations
near Frome, Somersetshire, which gives further evidence of the Plesiosauroid

* Report of the British Association, 1859, p. 153.

+ Volume of the Paleeontographical Society, 4to, for 1851.

{ This genus was established, on the characters of detached teeth from the Chalk, in the author’s
“Report on British Fossil Reptiles,’ ‘Trans. of the British Association,’ 1841, p. 156.

§ 4to, 1848, tab. xxviii, fig. 3.

|| Monograph, cit. pp. 201—209.

@ Ibid., p. 206.

1

CRETACEOUS FORMATIONS. 21

affinities of the genus, in the presence of a large oblique “foramen parietale”’
between the frontal and parietal bones (Tab. IV, fig. 1, p).

The parietal bone (7) is much compressed, and developes a sharp and rather lofty
median crest behind the foramen (p), which crest divides the temporal fossz (s, ¢).
Behind this crest the parietal bone expands transversely, and assumes a tri-radiate
form, the two transverse rays uniting with the mastoids (8, s). These are very
powerful bones, bounding the outer and back part of the temporal fosse; they
are smooth and slightly convex above, rough and slightly concave at the back
part near the angle, where a surface is thus formed for the attachment of some
powerful muscle. The part of the mastoid which curves forward from the angle
to form the back part of the zygomatic arch, becomes compressed, and terminates
above in a ridge (,). The substance of the mastoid is extensively excavated, appa-
rently for the upper part of the acoustic chamber.

The frontal bone (11) is overlapped behind by the parietal, and appears to
have been divided by a median ‘‘harmonia,” or smooth suture; the receding
halves of the frontal behind, as they pass beneath the parietal, form the forepart
of the foramen parietale. The back part of the foramen is formed by a notch
in the forepart of the single and undivided parietal. The canal from the fora-
men extends obliquely downward and backward. The long diameter of the
foramen is 1 inch; the breadth of the back part of the cranium is 16 inches; the
breadth of the back part of each temporal fossa is 63 inches. The power of the
muscles acting upon the lower jaw must have been very great.

A portion of a symmetrical bone, 10 inches long, which formed the upper
median part of the face, anterior to the orbits, represents part of an undivided
nasal bone (15) and shows that bone to have been long, narrow, straight longi-
tudinally, convex transversely above, as if the upper part of the face had been
traversed by a low, obtuse, median rising.

In most of these characters may be discerned a closer affinity to the Plesio-
sauroid than to the Crocodilian type.

The expanse of the temporal fosse equals that in the Plesiosauri and Teleo-
sauri, but no species of the latter genus of Crocodilia has presented the “ foramen
parietale,’ whilst it is a constant character in the Plestosauri, Ichthyosauri,
and Labyrinthodontia; many of the modern lizards also present the same
foramen. The portion of the upper maxillary bone, figured of the natural
size at fig. 2, Tab. I, shows the same obliquity of the separate sockets of the
teeth as exists in those at the forepart of the bone in certain Plesiosaur?, and
the small separate foramina (o, 0), at the inner and back part of the large alveoli,
which had been perforated by the summits of the successional teeth, are of
plesiosauroid character. I have seen portions of jaws of Plesiosaurus
megacephalus in which the appearance of a double row of teeth was caused by

22 FOSSIL REPTILIA OF THE

the length of the protruding summits of the new teeth before they displace the
old, when they are pushed, causing absorption of the intervening osseous bar,
into the large sockets of the teeth they replace.

The crown of the teeth of Plesiosaurus is, moreover, one which that of
the teeth of Polyptychodon (fig. 3) resembles in the ridged enamelled sur-
face and sub-circular transverse section; but the teeth of true Plesiosauri are pro-
portionally longer and more slender, whilst those of Polyptychodon in the
proportions of the crown more resemble the teeth of the crocodilian genera
Goniopholis and Madrimosaurus.

The microscopic structure agrees equally with the plesiosauroid and cro-
codilian modifications of the dental tissues. In Tab. I, fig. 3, 2 shows the shape
of the base of the deeply implanted tooth, at the part where it had been broken in
one of the specimens (a), accompanying the portion of cranium from the Lower
Chalk at Frome. Fig. 3 is a more entire tooth of the same individual.

Cervical Vertebra (Tab. V, figs. 1 and 2).

I next proceed to offer other evidences tending to show the affinity of Poly-
ptychodon to Plesiosaurus. In the Upper Green-sand deposits near Cambridge,
and in the Neocomian formations of similar age at Kursk, south of Moscow,
large vertebra of the Plesiosauroid type have been discovered, together with
teeth of Polyptychodon, which vertebre I believe to belong to that genus.

The centrum of a cervical vertebra, from the Cambridgeshire Upper Green-
sand (figured in Tab. V, figs. 1 and 2), measures 4 inches 3 lines in length, 5
inches 8 lines across the terminal articular surface, and 7 inches in total breadth,
including the transverse processes (pi, pi). Each of these projects about an inch
from the side, rather nearer the fore than the back part, of the vertebra, and
terminates in a flattened surface for the ligamentous articulation of the cervical
rib, which surface measures 2 inches 3 lines by 2 inches in its diameters
(fig. 1, p?). The articular surfaces of the centrum are nearly flat. :

This vertebra, with which no other teeth save those of Polyptychodon,
from the same formation and locality, agree in size, thus presents the essential
characters of the neck-vertebree of Nothosaurus and Plesiosaurus, and must
be referred to the order Sauropterygia.* The specimen is preserved in the
Woodwardian Museum at Cambridge. It was obtained from the Green-sand

* See the “Classification of Reptilia,” ‘ Reports of the British Association,’ 1859, p. 159, and ‘ Palz-
ontology,’ 8vo, 1860, p. 209.

CRETACEOUS FORMATIONS. 23

phosphatic-nodule works at Haslingfield, about four miles from the town of
Cambridge.

In a collection of Upper Green-sand fossils from the vicinity of that town,
lately purchased by the British Museum, there is the centrum of a dorsa] vertebra
of corresponding dimensions. It presents the usual characters of the Plesio-
sauroids; the articular ends are very slightly concave, with a moderate promi-
nence in the middle, of a subcircular form, about the size of a crown-piece.
The sides are gently concave lengthwise; the under surface is so in a less
degree; this non-articular surface is smooth at the middle part, with longitudinal,
irregularly wavy ridges and grooves for an inch at the margin, which are well
defined ; this roughness indicates the attachment of the fibres of the capsular
ligament. The fore-and-aft diameter of the centrum is less at the summit than
at the base; here it measures 4 inches 6 lines; along the neural canal it is 4
inches; the smooth tract caused by the impress of this canal is 6 lines across the
narrowest part, and 2 inches across the widest end. ‘The neurapophysial pits are
shallow, with a rugged surface 3 inches 6 lines long by 1 inch 9 lines in diameter ;
the small part of the upper surface of the centrum not covered by the neurapo-
physis is at the end where the neural canal is widest, and which is most probably
the hinder end; there are two venous foramina on one side and three on the
other side of the middle of the lower surface of the centrum. The breadth of
the articular surface is 6 inches 3 lines; its depth, or vertical extent, the same.

The same conformity, in regard to their proportional size, characterises the
teeth of Polyptychodon and the associated large Plesiosauroid vertebre from
Kursk. I am indebted to the able engineer and zealous paleontologist, Colonel
Kiprianoff, for the opportunity of examining the specimens discovered by him in
that locality.

The centrum of one of these vertebrz belonging to the dorsal region, from the
Neocomian formations at Kursk, measures 4 inches in length and 5 inches 4 lines
in breadth; the terminal articular surfaces are flat ; between them the lower surface
of the centrum is straight, but at the sides it is gently concave; there are two
venous foramina, 2 lines apart, at the middle of the under surface of the
centrum.

Portions of ribs from the Upper Green-sand of Cambridgeshire agree in
texture, and correspond in proportional size, with the cervical and dorsal vertebral
bodies with which they were associated. I have selected one of these fragments
for representation in Tab. V, fig. 3, because it shows a well-marked ridge (s) on
one side, a character I have not seen in the ribs of true Plesiosauri; and these
portions of ribs, of probably Polyptychodon, present a less rounded transverse
section.

24 FOSSIL REPTILIA OF THE

Atlas and Axis (Tab. V1).

The centrums of the first and second cervical vertebrae coalesced, as in
Plesiosaurus, from the same locality and formation as the hinder cervical vertebra,
Tab. V, present the proportions, in regard to their antero-posterior diameter, of
the cervical vertebre of Pliosaurus; but they belong, in all probability, to
the same Plesiosauroid reptile as the vertebre previously described, and I refer
them to the genus Polyptychodon.

Like most of the fossils from the Haslingfield locality, they have been subject
to attrition. The contour of the centrum of the atlas (fig. 1) has been subcir-
cular; its anterior articular surface (c, a,) is concave, and has afforded a large pro-
portion of the bottom or middle part of the cup for the occipital condyle. The
lower part of the cup has been completed, as in Plesiosaurus, by a wedge-shaped
hypapophysis, the articular surface for which is shown at 4, ,; the upper contour
has been contributed by the neurapophyses, the articular surfaces for which may
be discerned at x, p, on each side of the smooth neural tract n, in figs. 2 and 3.

The line of the original separation of the bodies of the atlas and axis may be
traced; the second hypapophysis, or part of it, remains anchylosed to their inferior
interspace; it has been much smaller than the first. The posterior surface of the
centrum of the axis vertebra (fig. 2, ¢, ~) is almost flat, showing the Plesiosauroid
nature of the bones. In the similarly short vertebree of an Ichthyosaurus, this
surface would have been deeply concave.

Having thus a proof of the piesiosauroid nature of these anchylosed vertebre,
the same grounds for referring them to Polyptychodon apply, as to the pos-
terior cervical vertebra (Tab. V, figs. 1 and 2) of more ordinary plesiosaurian
proportions. Between that vertebre and the axis I infer, therefore, that the
anterior cervicals rapidly diminished in length, and that the anterior ones exhi-
bited the same Ichthyosaurian shortness as they do in Pliosaurus. The mag-
nitude of the head, jaws, and teeth, of Polyptychodon resembled that of its
more ancient congener from the Kimmeridge Clay, and the supporting part of the
spinal column appears to have been shortened and strengthened accordingly.

It is probable that the large Plesiosauroid paddle, from the Chalk of Kent, the
phalanges of which are figured in the ‘ Monograph on the Fossil Reptilia of the
Cretaceous Formations, for 1851 (Paleont. Soc.), pl. 17, belonged to Poly-
_ ptychodon. Thus the evidence at present obtained respecting the huge but hitherto
problematical carnivorous Saurian of the Cretaceous period proves it to have
been a marine one-—the rival and contemporary of the equally huge Maestricht
lizard. But whilst Mosasaurus, by its vertebral, palatal, and dental characters,
oreshadows the saurian type to follow, Polyptychodon adheres more closely

CRETACEOUS FORMATIONS. 25

to the prevailing type of the sea-lizards of the great geological epoch then draw-
ing to its close.

The seas in which the English Chalk hills and cliffs were formed, and by which
they were modified in the course of upheaval, must have teemed with life, and
have been traversed by shoals of fishes needed for the sustentation of the numer-
ous kinds of large marine reptiles now known to have existed during that period,
and all of which were provided with jaws and teeth adapted, under diverse secon-
dary modifications, to the capture and destruction of the finny races. Of these
carnivorous reptiles some, as, e. g., [chthyosaurus campylodon and Plesiosaurus
Bernardi, were large species of genera represented throughout the oolitic period ;
others, as, e. g., Leiodon and Mosasaurus, offer generic or family modifications
of the Saurian structure, unknown in any other than the Cretaceous deposits.
The subject of the present section, as gigantic as the Maestricht Mosasaur, mani-
fests an extreme modification of the Plesiosauroid type of structure. It is pro-
bable that the large Pterodactyles of the same geological period, soaring like
albatrosses and giant petrels over the Cretaceous seas, co-operated with the marine
reptiles, as those sea birds now do with cetaceous mammals, in reducing the ex-
cessive numbers of the teeming tribes of fishes, and in maintaining the balance of
oceanic life.

TAB. I.

Pterodactylus Simus.

1. Fore part of the upper jaw, left side.
2. Ditto, right side.

3. Ditto, front view.

4. Ditto, upper view.

5. Ditto, under view.

6. Hind part of the right ramus of the lower jaw, inner side.
7. Ditto, outer side.

8. Ditto, under side.

9. Ditto, upper side.

10. Ditto, section.

11. Occipital condyle.

12. Basi-occipital, side view.

13. Ditto, upper view.

14. Atlas and axis vertebre, front view.
15. Ditto, side view.

16. Ditto, back view.

The foregoing figures are of the natural size, and from specimens
in the Woodwardian Museum of the University of Cambridge;
they were obtained from the Upper Green-sand formation near that

town.

Jos Dinkel ith

TAB. II.

Pterodactylus Simus and Pter. Woodwardi.

. Middle cervical vertebra, under view.

. Ditto, upper view.

. a. Fragment of jaw, section.

b. Ditto, side view.
ce. Ditto, section of tooth.

4. Lower cervical vertebra, oblique view.

Or

. Glenoid articular cavity formed by the anchylosed ends of the scapula and

coracoid.

. Scapho-cuneiform (?) carpal bone.

. Fore part of sternum, side view.

. Ditto, upper view.

. Ditto, under view.

. Fore part of a smaller sternum, side view.

. Ditto, upper view.

. Ditto, under view.

. Anterior caudal vertebra, under view.

. Ditto, upper view.

. Middle caudal vertebra, under view.

. Ditto, upper view.

All the figures are of the natural size, and from specimens in the
Woodwardian Museum of the University of Cambridge ; they were
found in the Upper Green-sand formation near that town.

Dmkel hth

Jos

i)

Pm Oo

bat

oO

10.
me
12

=:

EDAB. Te

Humerus of Pierodactyle.

. Proximal or upper end of right humerus, oblique view of palmar and ulnar

surfaces.

. Ditto, anconal surface.
. Ditto, palmar surface.

. Proximal end of a left humerus, drawn without reversing, oblique view as

in fig. 1.

. Proximal end of a right humerus of a smaller species of Pterodactyle,

oblique view as in figs. 1 and 4.

. Proximal end of the right humerus of a bird (Vultur monachus), oblique

view of palmar and ulnar surfaces.

. Ditto, anconal surface.
. Ditto, upper surface, or head.

. Proximal end of the right humerus of a crocodile (Crocodilus biporcatus),

oblique view of palmar and ulnar surfaces.
Ditto, anconal surface.
Ditto, oblique view of the palmar and radial surfaces.

Ditto, upper surface, or head.

All the foregoing figures are of the natural size; 1 and 3, probably of
Pterodactylus Cuvieri, are from the White Chalk of Kent ; 4, probably
of Pter. Sedgwickii, and fig. 5, are from the Upper Green-sand
formation, near Cambridge. The foregoing specimens are in the
Woodwardian Museum of the University of Cambridge.

We

TAB. IV.

. Upper view of a part of the cranium of Polyptychodon interruptus; one

fourth the nat. size.

. Fragment of the alveolar part of the same cranium; nat. size.

. A tooth of the same specimen, side view, nat. size; a, ditto, opposite side ;

b, ditto, section of fang, showing pulp-cavity.
Basal half of a tooth of Pterodactylus simus ; nat. size.

Unciform? carpal bone of Pterodactylus Sedgwickii, proximal? surface.

. Ditto, distal? surface.

. Scapho-cuneiform? carpal bone of Pterodactylus Sedgwickit, proximal?

surface.

. Ditto, distal 2 surface.

. Ditto, side view.

. Ditto, end view.

. Ungual phalanx of Pterodactylus Sedgwickii, side view.

. Ditto, upper view.

LEY

st amp

Ye

WH

1
Basser

Dinkel

wo
e
8

TAB. V.

Polyptychodon interruptus.

o
Fig.

1. Centrum of posterior cervical vertebra, side view.
2. Ditto, under view.
3. Fragment of a dorsal rib.
These figures, of the nat. size, are from specimens in the Woodwardian

Museum of the University of Cambridge; and are from the Upper
Green-sand formation near that town.

ave

okel Lith

Jos Ds

PA aie enna) irae wer nen eae

'

co 5)
s |
i
'

\

p ra

‘ +
‘
ry
2
ry
~ F 1

Pini a

TAB. VI.

Polyptychodon interruptus.

Fig.
1. Centrum of the atlas vertebra, front view.

2. Centrum of the axis vertebra, back view.
3. Anchylosed centrums of the atlas and axis vertebre, upper view.
4. Ditto, side view.
These figures, of the nat. size, are from a specimen in the Woodwardian

Museum of the University of Cambridge, discovered in the Upper
Green-sand formation near that town.

VD

t
k
b
=

MONOGRAPH

ON

THE FOSSIL REPTILIA

OF THE

CRETACEOUS FORMATIONS.

SUPPLEMENT No. IV.

Paces 1—18; Prares I—IX.

SAUROPTERYGIA (Przstosavrts).

BY

PROFESSOR OWEN, D.C.L., F.RS., F.LS., F.GS., &.
Issued in the Volume for the Year 1862.
LONDON:

PRINTED FOR THE PALZONTOGRAPHICAL SOCIETY.
1864.

SUPPLEMENT (No. IV)*

MONOGRAPH
DEE BOSSI REP Bie WA

CRETACEOUS FORMATIONS.

Orper—SAUROPTERYGIA, Owen.
Genus—P.eEsiosaurus, Conybeare.

In former Monographs and works are given descriptions of the following
species of Plesiosaurus from Cretaceous deposits :

PLEsIOSAURUS ConsTRICTUS, Owen. ‘ Dixon’s Geology and Fossils of the Tertiary
and Cretaceous Formations of Sussex,’ 4to,
1850, p. 398, pl. xxxvii, figs. 6 and 7.
From Steyning Chalk-pit, Sussex.
Pxesrosaurus Bernarpi, Owen. Op. cit., p. 396, pl. xxxvii, figs. 8, 9. From
the Upper Chalk, Houghton Pit, near
Arundel, Sussex.
PLesiosauRUs PAcHYomuUsS, Owen. Monograph, Paleontographical Society, 4to,
1851, p. 64, tabs. xx, xxi. From the Upper
Greensand at Reach, near Cambridge.
PLESIOSAURUS LATISPINUS, Owen. ‘ Descriptive Catalogue of the Fossil Remains
of Reptilia and Pisces in the Museum of
the Royal College of Surgeons of England,’
Ato, 1854, p. 63, No. 251.
* This Memoir was given as ‘Supplement No. II,’ in the volume for 1862.

1

2 FOSSIL REPTILIA OF THE

PLEsIOsAURUS NEOCOMIENSIS, Cpche. ‘Description des Fossiles du Terrain Cre-
tacé des Environs de Sainte-Croix,’ 4to,
1858—1860, par N. J. Pictet and G.
Campiche, p. 12, pl. vi.

The following are descriptions of other species of Cretaceous Plesiosauri, with
additional illustrations of already indicated species :

PLESIOSAURUS PLANUS, Owen. Vertebral Centrums, Tab. I, II, and III.

The cervical centrum selected for the figures 1—4, Tab. I, gives the characters
afforded by this instructive part of the vertebral column of a Plesiosaurus. The
flatness, both of the under (fig. 4) and of the terminal articular surfaces (fig. 2),
suggested the name distinguishing the species, or at least the vertebree by which
alone this cretaceous Plesiosaur has hitherto been exemplified. The costal sur-
faces (‘Tab. I, figs. 1, 2, and 4, pi) are of a narrow, oblong figure, formed, as it were,
by truncation of the lower angles of the triangular centrum, of which the apex has
been more broadly removed by the sections, leaving the neural (ib., x) and neurapo-
physial (np) surfaces above. If the borders of the costal surface have projected
with a sharper definition, they have been abraded, as, indeed, is most probable ;
almost ail the bones derived from the stratum of Cambridgeshire phosphatic Green-
sand being more or less rubbed or worn, either in the original imbedding, or sub-
sequently by the mechanical appliances by which the phosphatic nodules are ex-
tracted. I have selected the centrum which has been least subject to this attrition,
from a large series of the present species. Subsequent observers, who may have
been favoured with entire and unworn fossil vertebrae with the main features and
proportions of the Plesiosaurus planus, will make allowance for the circumstances
in which the materials for reconstructing that species first came to hand.

What may be more certainly predicated of the costal surface is the absence of
depth and of linear horizontal bisection, both which characters are present in the
cervicals of some other Plestosauri. The distance between the costal and neura-
pophysial surfaces is nearly three times that of the vertical diameter of the former,
and the intervening non-articular surface is smooth, and also plane or flat, sloping
upward towards the neurapophysial border, and showing no sinking or concavity
in the longitudinal direction. The neural surface, 23 lines in breadth at the
narrowest part, slightly expands towards the posterior surface of the centrum.
The neurapophysial surfaces are coextensive with the long or fore-and-aft diameter
of the centrum, and of nearly equal breadth anteriorly; they are smooth and very
shallow, with a slightly defined, thin border, which is undulated outwardly, descend-

CRETACEOUS FORMATIONS. 3

ing lower upon the fore than upon the hind half of the centrum, and giving, in the
pair, a contour somewhat like that of a saddle; I do not, however, insist upon this
as a constant character of the cervicals of this species. In the present vertebra
one of the venous orifices-is larger than the other ; but in a second, of similar size
and contiguous position, they show the usual equality. The flatness of the ter-
minal surfaces is remarkable, and betokens restriction of the movements of the
neck of the species. On the similarly flattened under surface the venous foramina
(fig. 4, ») open nearer the anterior than the posterior border.

In a cervical vertebra, of similar size and proportions, the neurapophysial sur-
faces are more concave in the longitudinal direction. As the cervical series
approach the back the centrums increase in length, while preserving about the
same relative breadth. In the vertebra, figs. 5—7, the costal surface (p/)has risen to
the neurapophysial one (np), with which it has become confluent ; the inferior tract of
the centrum now describes a convexity between the two costal surfaces, though it
is but slight; the contour of the terminal surface accordingly presents the form of
a transversely elongate ellipse (fig. 6). ‘The fore-and-aft contour of the under
surface is very slightly concave, almost flat. ‘The posterior border of the costal
surface is produced, forming the beginning of a parapophysis (fig. 7). The
neurapophysial surfaces are slightly excavated, with a defined but hardly raised
border; they are undulated, smooth, with scattered foramina ; their breadth is now
one third more than their length. In the posterior cervical (fig. 7) the venous
canals on the neural surface show the same inequality as in fig. 3.

In the vertebra in which the costal surface has wholly passed upon the neur-
apophysis (fig. 10, np), and which, from the proportions of length to breadth, is to
be reckoned as coming from the beginning of the dorsal series, the sides of the
centrum are excavated under the neurapophysial surfaces; but below the excava-
tion, which is not deep, the longitudinal contour is as nearly straight as in the
antecedent vertebra.

To one of the terminal surfaces of this vertebra (fig. 11) adheres the remnant
of the lower valve of the spondyloid shell—Dianchora striata : the living Spondylus
Gussont, which most resembles the characteristic Green-sand bivalve, dwells at
great depths in coral-beds of the Mediterranean. We may conceive, by analogy,
that the carcass of the dead Plesiosaur, sinking and decomposing in a similar
chalky manufactory, left its scattered bones to serve as the resting-places of those
bivalves of its locality and period which, like the modern smooth and spiny oysters,
anchor themselves for life after a brief locomotive period.

Towards the middle region of the back the centrums gain in vertical diameter,
and somewhat in length, with a diminution of their transverse diameter. ‘The
concavity of the non-articular surface from before backward is still greatest near
the neurapopnysis, but has less the aspect of a circumscribed depression than in

4 FOSSIL REPTILIA OF THE

the anterior vertebra. The neurapophysial pits now diminish in breadth, pre-
serving their length nearly coequal with that of the centrum itself. The terminal
articular surfaces show a slight sinuosity, feebly concave, with a less convexity at
the middle part. The under surface still retains an aspect of flatness, both trom
before backward and from side to side. Most of these mid-dorsal vertebra show
a slight difference of length in the two sides, as in figs. 9 and 14.

In one dorsal vertebra (fig. 26) a terminal articular surface, showing a porous or
spongy character, is also marked by irregular grooves converging toward the
centre, like the corresponding surface of a Cetaceous vertebra from which the
epiphysial plate had become attached. Save in this single instance, I never met
with such an appearance in a Plesiosaurian vertebra; the opposite surface is
smooth, as are both surfaces in the other vertebree of P/. planus.

In the tail the broad and short proportions of the vertebral centrum are resumed
(figs. 16—19), but with a more marked concavity of the terminal articular surfaces,
which in one vertebra showed fine lines radiating from the centre. A broad, but
almost flattened, border extends from the terminal surface upon the side of the
centrum, joining the costal surface, and expanding to mark the place and extent
of attachment of the hamapophyses. The diminished size and feebler impression
of the neurapophyses bespeak the reduction of the neural arch at this part of the
vertebral column. The pleurapophyses retain their independency, and were
articulated to a small subcircular surface on the upper half of the side of the
centrum ; the lower half is almost flat, and joins, at an open angle, the equally flat,
broad under surface, which is bordered, like the sides, by the deflected tract from
the articular ends. The venous canals open upon the middle of the under surface,
about four lines apart.

A few small vertebral centrums belonging to the present series, and apparently
from a similar-sized Plesiosaur, if not part of the same individual, seem to be
reduced to the simplicity of supporting only neurapophyses, and show no distinct
marks of articulations for either pleur- or hem-apophyses. The centrums are
broad, depressed, with perfectly flat terminal surfaces, and a flattened under
surface. ‘They may come from the beginning of the neck, or from the end of the
tail. I reject the latter notion, because the analogy of the terminal caudal ver-
tebrae, or those in which the hemapophyses ceased to exist, in other Plesiosauri,
would lead one to expect a concavity of the articular surfaces, and a diminution
in the lateral rather than in the vertical direction, a compressed rather than a
depressed form. Assuming, then, that these vertebre are from the beginning of
the neck, the question next arises whether pleurapophyses were wholly absent, or
whether they were so small and so feebly articulated as to leave no sign of their
attachment, at least after the degree, slight as it is, of superticial abrasion te
which the fossils have been subject. I think the latter condition may be the more

CRETACEOUS FORMATIONS. 5)

probable one, although in some species of Plesiosaurus, as e.g. the present, the
“hatchet bones” or cervical ribs might only commence on the third or fourth
vertebra, beyond the coalesced atlas and axis. As a general rule, they begin on
the second cervical.

Thus, the characters of the Plesiosaurus planus are exemplified, so far as they
are shown by the vertebral centres, from all the chief regions or parts of that
column. The majority of the vertebrae which have served for the comparisons
and illustrations leading to the above-given information as to the species, have
been kindly confided to me for that purpose by the Rev. Adam Sedgewick, F R. S. ,
Woodwardian Professor in the University of Cambridge.

These vertebre differ from those of all the previously described species of
Cretaceous Plesiosaurs in the proportions of breadth to length, especially in the
cervical region, and in the flatness of the terminal articular and of some other
surfaces of the centrum.

Several larger vertebrae have reached me singly, as though from a more
scattered disposition of parts of the dislocated skeleton in the phosphatic Green-
sand bed of Cambridgeshire, which agree in character with the Plesiosaurus planus.

In the Plesiosaurus pachyomus the centrum increases in breadth as it approaches
the back, whilst some of the dorsal vertebra offer almost the same proportions as
those in the above-described series.

But the difference in the corresponding cervical vertebree is very striking, as is
exemplified in the following comparative admeasurements.

Admeasurements of vertebral centrum :—

Anterior cervical. Middle cervical.
Pl, pachyomus. Pl. planus. Pl. pachyomus. Pl. planus.
Tn. lines. In. lines. Tn. lines. In. lines.
Antero-posterior diameter or length . ey 9. : 0 11 : 20) . Ie 8
Transverse diameter or breadth : 3-3} ; 1 10 : 203 : Me &
Vertical diameter or height 1) eel é yh 8 b 1.3}

The centrum (Tab. II, figs. 1 and 2) is of a vertebra from the posterior part of
the neck. The anterior articular surface presents a transversely elongate elliptical
form (fig. ]), contrasting with the almost circular contour of the same part in
Plesiosaurus pachyomus (Monogr. 1851, Tab. XX, fig. 2). It is very slightly, but
uniformly, concave. ‘The neurapophysial pits (fig. 2, np), of a triangular form, and
coextensive with the fore-and-aft extent of the centrum, are divided by a neural
canal (fig. 2, nj, of about 4 lines in breadth, and their lower angle, which is rounded
off, projects from the side of the centrum, which is not the case in Plestosaurus
pachyomus. ‘The costal pit (Tab.I, fig. 1, p2) is much smaller than in Plestosaurus

6 FOSSIL REPTILIA OF THE

pachyomus (1. c., Tab. XX, fig. 1, pi). The under surface of the centrum is flat
from before backward, and describes a gentle uniform convexity from one costal
pit to the other.

The vertebral centrum, Tab. II, figs. 3, 4, 5, is from the base of the neck,
and from a larger individual. The bases of the neurapophysial pits (fig. 4,
np) have not been coextended with the increased length of the centrum, and the
apex contracts more quickly, and is extended to the upper division of the costal
pit. The breadth of the neural surface (ib., ») is the same as in the more anterior
cervical centrum (fig. 2); but the orifices of the venous canals are more con-
spicuous. Only a small part of the costal pit (ib., p1) now marks the centrum;
it projects from the side of that element, nearer its posterior surface. The
articular surfaces of the centrum (ib., fig. 3, ¢) are nearly flat, and slightly undu-
lating, without a central pit. ‘The lower orifices of the venous canal are about
two lines apart.

The centrum, Tab. II, figs. 6—9, is from the base of the neck of another and
larger individual of the Plesiosaurus planus, and, with a moderate increase of all
its dimensions, shows least that of breadth. The articular surface of the centrum
(fig. 6, c) hasa shallow depression at its middle part, occupying about half the breadth
of the surface; it is flat at the circumference, and its margin, though obtuse, is
narrow and well defined. The narrow outer part of the neurapophysial tract (ib.,
fig. 9, np) has a well-defined raised border, terminating in the major part of the
costal surface, the lower half of which is much reduced in size; the interspace is
occupied by a small mass of matrix. The under surface shows a slight concavity
from before backward. The non-articular surface of the centrum is almost
smooth.

A similar and closely succeeding vertebral centrum of the same species of
Plesiosaurus is figured in Tab. III, figs. 5 and 6. It is more mutilated, and a
portion of a rib is cemented to the neural surface (fig. 6). The costal surface has
risen wholly upon the neurapophysis (np), the base of which adheres to the
centrum, and projects outward as a cestal diapophysis (@). ‘This centrum is
from the fore part of the dorsal region.

The cervical centrum (Tab. ITI, figs. 1—4) appears to have come from the basal
third of the neck, perhaps from the beginning of that part, in which the contour
of the articular surface, expanding towards the lower part, takes on, as in the
antecedent cervicals (Tab. I, fig. 2), something of a triangular form; here, however,
the shape of the neurapophysial surfaces (zp) is of a more regular triangular form
(compared with fig. 2, Tab. II) and they are connected by a narrow, slightly elevated
tract with the costal pit (pi). This articular surface begins to diminish in antero-
posterior extent, indicating a corresponding change in the shape of the shaft of
the costal rib; the terminal articular surface of the centrum has a slight central

CRETACEOUS FORMATIONS. 7

depression, of the same relative extent as in fig. 6, Tab. II. The under surface
(Tab. III, fig. 4) is almost flat, both lengthwise and transversely; the venous
outlets present the same relative position, and the non-articular surface of the
centrum shows the same degree of smoothness and flatness as in the smaller ver-
tebree (Tab. I, figs. 2, 6). 'The present centrum belongs to the same species of Ple-
siosaurus as those of the more regular elliptical form, andis merely indicative of a
different position in the region of the neck.

A centrum with the surface much abraded (Tab. III, fig. 8) appears to have
presented the same inferior expansion, and consequent triangular form, as fig. };
but in the under surface (fig. 9) the venous canals have opened into well-marked
depressions. Other differences, as in the character of the neurapophysial surfaces
(fig. 7, np), may be due to the degree of abrasion to which the present fossil has
been subject.

Piesiosaurus Bernarpl, Owen. Cervical Vertebre. Tab. LV.

In my ‘Monograph of the Fossil Reptilia of the Cretaceous Formations,’
Volume of the Palzontographical Society for 1851, p. 60, I characterised a species
of Plesiosaurus from a cervical vertebra then in the museum of my esteemed
friend, Freperic Dixon, Esq., of Worthing, under the name of Plesiosaurus
Bernardi, which vertebra was figured in Plate XVIII of the above-cited Mono-
graph. I have subsequently had the opportunity of examining several other
vertebre of a Plesiosaurus from the Green-sand of Reach, near Cambridge, which
are referable to the same species, but most of them to an individual of smaller
size, and probably of immature age.

The specimen (Tab. IV, figs. 1, 2, 3, 4) is an anterior cervical vertebra, which
agrees with the more posterior one above figured in the degree of concavity of
the articular surfaces of the centrum, in the extent of the peripheral border of
that cavity, which is convexly bevelled off (“évasé”), and in the relative position
of the neur- and pleur-apophyses; the breadth of the centrum is not so much
greater proportionally to the length; but this difference I believe to be due to the
more anterior position in the vertebral series from which the present specimen
has been derived.

The neurapophysial depression (np) is deep and smooth, encroaching further on
the convex border of the centrum at its back than at its fore part; they are
divided at the upper surface of the centrum by a neural tract (fig. 3, n), about 2
lines broad at its narrowest part. The non-articular surface of the centrum is
moderately smooth, especially at the sides between the neur- (np) and pleur- (p/)

8 FOSSIL REPTILIA OF THE

*

apophysial pits, (fig. 1); its vertical extent here is not quite equal to that of the
pleurapophysial pit. Thisis of an oblong oval shape, less deeply concave than the
neurapophysial pit, with a smooth surface, nearer the posterior than the anterior
surface of the vertebra, with the border slightly prominent (fig. 4, pi). The
venous foramina at the lower surface (fig. 4) are situated in depressions, divided
by a ridge-like narrow tract of the centrum. In this character, but more espe-
cially in the depth of the terminal articular surfaces, with their broad and thick
convex border, and in the position of the riblet, the present centrum is referable
to the Plestosaurus Bernardi.
The following are dimensions of this cervical centrum:

Pl. Bernardi.

In. lines.
Antero-posterior diameter or length . ; : c : Ne e2
Transverse diameter or breadth : : ; 5 : 1 4
Vertical diameter or height : 5 : 0 ; é 1 4

The centrum, Tab. IV, figs. 5 and 6, appears to have succeeded the foregoing
in the same cervical series, with, perhaps, the intervention of one or two vertebre.
It is similar in colour and mineral character, and from the same locality. It
repeats the distinctive characters of Plesiosaurus Bernardi. It indicates by a
slight obliquity the effects of posthumous pressure.

This mechanical force has distorted in a greater degree a centrum (Tab. IV,
figs. 7 and 8), doubtless from a more posterior part of the same neck. The
margins of the pleurapophysial pits are here rather more produced. The middle
of the deep concavity of the terminal surfaces is impressed by a transverse pit or
linear mark (fig. 8).

Col. Kiprianoff, of the Imperial Russian Engineer Corps, submitted to me
some plesiosaurian vertebra from the Neocomian deposits, or Green-sand, of
Kursk, in the district of Kursk, near Moscow, which offered all the characters of
the Plesiosaurus Bernardi. A cervical vertebra, intermediate in size between figs. 6
and 7, shows a partial anchylosis to the centrum of both neur- and pleur- apophyses.
The riblet was confluent to a surface near the lower part of the centrum, about
the same distance from the neurapophysis as in the first-described vertebra (fig. 1)
from the Cambridge Green-sand. The under surface was ridged or pinched up,
as it were, between the venous foramina, each of which was also situated in a
depression between the median ridge and the base of the riblet. This element
expanded, and its posterior angle was produced backward, The following were
the dimensions of the centrum of this vertebra:

CRETACEOUS FORMATIONS. 9

Plesiosaurus Bernard.

In. lines.
Antero-posterior diameter or length . : 3 : a : . as
Transverse diameter or breadth 0 : : : : : 5 1 7
Vertical diameter or height my i : . : ; 3 : Ii dl

In a more posterior cervical vertebra, from the same Russian locality, the
terminal articular surfaces are deeper towards the centre, with the out-turned or
“évasé” borders very thick. The base of the neurapophysis was here also par-
tially anchylosed, and the rib more completely so; it presented a rhomboid form,
being inclined backward as well as outward, with the anterior angle rounded, and
the posterior one produced. The inferior medial ridge was well marked. The
breadth of the centrum was relatively greater than in the preceding vertebra.

In the vertebrae from the Cambridge Green-sand (Tab. IV, figs. 9 and 10), which
have succeeded one another from about the same part of the neck, anchylosis of
the pleurapophysis has not been completed ; but that of the neurapophysis (np) has
been so to a degree sufficient for preserving their base in connection with the
centrum, although the summit has undergone fracture. The line of suture is,
however, very distinct.

The terminal surface of the centrum presents the same degree of concavity, with
aslight central horizontal linear depression, Tab. V, fig. 1,as shown in Tab. IV, fig. 8.
The base of the neurapophysis (np) extends to the anterior margin of the centrum, but
not quite to the posterior one. The outer surface of the neurapophysis presents a
low obtuse ridge or rising, extending from near the infero-posterior angle to the
outer side of the prezygapophysis (Tab. IV, figs. 9,10, 11, z) ; the aspect of the arti-
cular surface of this process is obliquely upward and inward. The posterior border
of the neurapopbysis is thicker, or more obtuse, than the anterior one; the
internal surface is smooth and even. Rather less than the vertical diameter of
the pleurapophysial pit (figs. 10 and 11, pi) intervenes between it and the base of
the neurapophysis (np). The inferior surface of the centrum presents the ridge
between the two depressions into which the venous vertical canals open.

In the vertebra (Tab. IV, fig. 11), from a more posterior part of the neck, or
from a larger Plesiosaurus, a greater proportion of the neural arch (xp) is preserved,
partially anchylosed to the centrum; the sides are strengthened by the same
oblique thickening, extending to the prezygapophysis (z); this is larger than the
postzygapophysis (2), and the breadth of the arch across the prezygapophyses is
nearly twice that across the posterior pair (Tab. V, fig. 6). The neural spine
appears to have been a thin plate; its base (Tab. V, fig. 6) extends from the notch
between the postzygapophyses (2) to within 3 lines of that between the prezyga-
pophyses (- ). This vertebra has been compressed laterally, and rather obliquely,
by posthumous pressure; yet under such general support that the neural arch,

fo)

~

10 FOSSIL REPTILIA OF THE

though apparently narrowed from side to side is not broken; the neural canal
(Tab. V, fig. 2, n) presents a vertical diameter of 11 lines, and a transverse diameter
of 7 lines. The costal depression (Tab. IV, fig. 11, pz) extends nearer to the
posterior than to the anterior surface of the centrum. The articular surfaces of
the centrum show the characteristic depth of the concavity, but with relatively
less thick obtuse borders, Tab. V, fig. 2.

The dimensions of this vertebra are:

Tn. lines.

Length of centrum . 3 : c j : c : : : We
Height of ditto : 2.0
Breadth of hinder surface of ditto : : 11s
From base of neurapophysis to end of pastidoamoplenis 2
From end of pre- to that of postzygapophyses 2 3
Breadth of neural arch across prezygapophyses . Ph 0)

”» Ds »» 9» postzygapophyses yy ul
Antero-posterior extent of base of ueural spine Liz(4

The vertebra, Tab. V, figs. 3, 4, and 5, appears to have come from the middle
of the neck of an older and larger Plesiosaurus, and it displays, ina striking degree,
the characteristics of that part of the Plesiosaurus Bernardi.

The depth of the concavity of the terminal surfaces of the centrum is almost
ichthyosaurian ; the breadth of the convex border of each cavity is extreme, and
is equally divided between the smoother articular surface continuous with that
of the concavity, and the surface roughened by fine concentric linear impressions,
forming the outer part of the border, and indicative of the strong circular liga-
ments which tied the vertebre together.

Anchylosis of both neur- and pleur-apophyses is here complete; and the
missing parts of both vertebral elements have been broken off. The neurapo-
physial suture is, however, traceable; and the characteristic distance between it
and the cervical rib is thus exemplified. The rising between the vascular depressions
on the under part of the centrum (fig. 4) is broader and less ridge-like than in
the more advanced vertebre of the neck. In this vertebra, in relation to its mere
posterior position in the neck, the transverse diameter has increased upon the lon-
gitudinal one, as is shown in the following admeasurements :

Length of centrum :
Breadth of ditto, posterior surface

The riblet, at its fractured surface (fig. 5, pl), shows an antero-posterior
diameter of 10 lines, a vertical diameter of 5 lines.

Valves of the fry, or young, of a species of Plicatula (2?) adhere to this fossil,
to which they attached themselves at the period when the cretaceous beds,

CRETACEOUS FORMATIONS. 11

receiving the carcases of the dead Plesiosaurt, were still in process of ena,
where now the dry land of Cambridgeshire has risen.

In a dorsal vertebra of this species, from the Neocomian deposits of Kursk, the
terminal articular surfaces of the centrum were less concave than in the neck, and
the lower surface was obscurely or very obtusely ridged. This vertebra measured
hn) e——=

In. lines.
Length . ‘ 5 5 ; E 5 5 é : a)
Breadth, anterior sur fbe of centrum . : ; a : ; : BG
_ posterior surface of centrum . : : : : : . Zs

A caudal vertebra of the same species of Plesiosaurus, from the same forma-
tion and locality, showed the hemapophysial surface best marked on the posterior
border of the centrum; they were each subtriangular in shape, 6 lines in long
diameter, and 1 inch apart. The pleurapophyses were anchylosed to the upper
part of the centrum, or over the base of the neurapophysis; but the sutural line
of juncture could be traced. The terminal surfaces of the centrum were mode-
rately and gradually concave, but with the broad obtuse border. The lower
surface was nearly flat and subquadrate, with only a feeble indication of a rising
between two small venous foramina. The length of this vertebra was 1 inch 7
lines, the breadth of the centrum was 2 inches 3 lines. 3

I have introduced the above notices of the vertebrze of the Plestosaurus Ber-
nardi from the Green-sand beds of the neighbourhood of Moscow, in illustration of
the geographical range of the species at the period of geological time in which
it existed; this period extending from the “ neocomian” to the “ upper chalk” of
the Cretaceous series. In the following section will be found a similar illustration
of the geographical range of another Cretaceous Plesiosaur.

PLESIOSAURUS NEOCOMIENSIS, Campiche. Cervical and dorsal vertebre ; humerus
and femur. Plate VI.

Professor Pictet and Dr. Campiche, in their excellent ‘Description des
Fossiles du Terrain Crétacé des Environs de Sainte-Croix,’ 4to, 1858—1860, have
described and figured three centrums of a dorsal vertebra of a Plesiosaurus, to
which Dr. Campiche has attached the name neocomiensis, inasmuch as these fossils
were derived from the lower neocomian or “ valanginian’’ beds of the Cretaceous
deposits described in the above work. And this name, although there be other
neocomian Plesiosaurs, and there may be many, [ retain for a species, richly
illustrated, from the Upper Green-sand deposits of Cambridgeshire, and which
I believe to be identical with Dr. Campiche’s.

12 FOSSIL REPTILIA OF THE

Dorsal centrums are usually the least significant of specific characters, owing
to the limitation of the articular surfaces to the neurapophysial and terminal ones,
and also owing to a resumption, more or less, in the dorsal region of the more
common proportions of the centrum, when this is departed from, either in excess
of breadth, depth, or shortness, in the cervical region.

Dr. Campiche’s description is so minute and exact that the correspondence of
the dorsal centrum (Tab. VI, figs. 9, 10, 11) with the characters expressed at p. 43,
op. cit., and shown in “ Plate VI” of that work, will be found to justify the specific
approximation. The centrum of Pl. neocomiensis is “a little broader than high, so
that the articular surfaces form nearly a transverse, very slightly elongated,
ellipse ; the shape would be even better expressed by a circle, of which the upper
part was flattened and subtruncate (see fig. 18).”* “ The length is sensibly inferior
to the two other dimensions ; the sides are strongly and gradually excavated, so that
when the vertebra is viewed from above,” (as in fig. 11, Tab. VI) op. cit., “its middle
part is much narrower than its articular surfaces. The inferior region, corresponding
to the medial line of the body, is more feebly excavated.{| The two large and deep
neurapophysial pits are slightly arched inwardly, and are two and a half times as
long as they are large; but the most significant character is the slight concavity
of the terminal surfaces, with their middle part feebly raised into an irregular
protuberance.”

In the larger of the dorsal centrums from the Swiss Neocomian, measuring
2 inches 7 lines in transverse diameter, the median rising is 10 lines in diameter, but
not more prominent than the more circumscribed rising in Tab.VI, fig. 10 of the pre-
sent Monograph. In the smaller Swiss centrum (Plate VI, fig. 2 of op. cit.) the central
eminence is broader and lower than in the nearly equal-sized centrum (Tab. VI, fig.
10) of the present Monograph; nevertheless, I am inclined to think that the mam-
millate character of the terminal articular surfaces shown in the cervical vertebrze
may, like other characteristic modifications, be less strongly manifested in the dorsal
vertebra, or in some of the dorsal vertebre of the same individual ; and, therefore,
I supersede my MS. denomination of Plesiosawrus mamillatus, under which I dis-
tinguished those vertebre from the Cambridge Green-sand, when first obtained

* «Un peu plus larges qu’ils ne sont hauts, en sorte, que leurs faces articulaires forment, a peu pres, une
ellipse transverse trés peu allongée. Leur forme serait méme mieux exprimée par un cercle dont la partie
supérieure serait aplatie et subtronquée.’’—Op. cit., p. 43.

+ ‘La longeur est sensiblement inférieure aux deux autres dimensions. Les flancs sont fortement et
graduellement excavés, en sorte que, lorsqu’on regarde la vertébre au dessus, sa partie médiane est beau-
coup plus étroite que les faces articulairés.”” ‘‘La région inférieure qui correspond a la ligne médiane des
corps est beaucoup plus faiblement infléchée. A la face supérieure, on voit deux grandes et profondes im-
pressions, correspondant a l’insertion des neurapophyses ou lames tectrices. Elles sont un peu arquees
en dedans, deux fois et demie aussi Jongues que larges, les faces articulaires sont legérement concayes, avec
leur milieu faiblement relevé en une protubérance irréguliére.’"—Op. cit., p. 43.

CRETACEOUS FORMATIONS. 13

for the British Museum, and adopt Mr. Campiche’s name, which has the priority
of publication, under the conviction of the specific identity of the vertebra from
the two localities.

All the mamillate vertebree I have yet seen from the Cambridge Green-sand
indicate a Plesiosaurus not larger than that represented by the smallest of the
dorsal centrums from St. Croix.

The cervical vertebrz (Tab. VI, figs. 1—4) shows a greater proportional trans-
verse dimension of the centrum than in the vertebra from the dorsal region (ib.,
figs. 9, 10), the sides of the centrum are less concave (compare fig. 4 with fig. 11) ;
on the inferior surface the shallow impressions into which the vertical venous
canals open, are divided by a narrow ridge-like tract (ib., fig. 4). The neurapo-
physial depressions (figs. 1 and 3, np) are broader than in the dorsal centrum, are
of a triangular form, and, as the intervening neural tract is of equal breadth (ib.,
fig. 3), it is relatively larger than in the dorsal vertebra (ib., fig. 11); the venous
foramina in this tract (fig. 3,2) are also wider apart. The costal surface (fig. 1, pt)
is large in proportion to the centrum, well defined, but not deep; transversely
elliptic; 9 lines in longitudinal by 6 lines in vertical diameter, and 3 lines distant
from the apex of the neurapophysial pit (np): it is situated rather nearer the pos-
terior than the anterior part of the centrum, and its margin slightly projects from
the level of the non-articular surface of the centrum; the distance between the
inferior borders of the two costal pits (fig. 4, pi) is 10 lines. ‘The terminal articular
surface (fig. 2) is less concave than in the Plesiosaurus Bernardi, and although
obtuse and convex at the circumference, is less thick or tumid there ; but the con-
spicuous and chief distinction is the well-defined mammillary eminence in the centre
of each of the terminal concavities. The following are dimensions of this centrum :

, In. lines.
Length . . : : 5 : : : : . : ¢ let oe
Breadth . 6 : : ; : A 5 : 4 : ; 8
Depth j , : : 5 é . ; : é f é [aes

Figures 5 and 6 represent a vertebra of apparently the same individual from
the base of the neck, where the costal surface (Tab. VI, fig. 5, p/) has almost wholly
ascended from the centrum upon the neurapophysis (np), and is more prominent
than in the average cervical vertebra. ‘The under surface of the vertebra is not
excavated or ridged, and is very slightly concave lengthwise ; it resembles that of
the average dorsal vertebre. ‘The mamillate character of the terminal articular
surface is as well marked as in the average cervical vertebre.

Figures 7 and 8 are of a posterior cervical vertebra of another individual, from
a different locality, in which the centrum is relatively shorter than in the two fore-

14 FOSSIL REPTILIA OF THE

going vertebre ; in other respects the characters closely accord with those of the
posterior cervical centrum (figs. 5 and 6), and I regard the present as indicating
a mere variety in the proportions of the centrum, which is also less than it
appears in the plate, on account of the abrasion of the circumference of one of
the terminal articular surfaces.

The dimensions of the restored centrum are:

In. lines.
MMSE og eee ey cee ea nn Ag ne ee
Breadth of posterior surface ; : , ; : : } TS: f33
Height. F . : : : : ; : : : . leer 6

The dorsal centrum (figs. 9, 10, 11) exhibits the characters already specified
in the comparison of it with the type-vertebra of Dr. Campiche’s species; the
chief or sole difference is the more circumscribed and smaller circumference of
the central mamilla of the terminal articular surface; the neurapophysial pits
have undergone the change of form and proportions which brings them to the
same pattern as in the dorsal vertebre figured in the ‘ Paléontologie Suisse,’
loc. cit.

In the locality whence the specimens (figs. 1—6, 9—11, ab. VI) were
exhumed, some portions of limb-bones were obtained of a Plestosaurus of cor-
responding size, of which I select for figuring a left femur (fig. 12) and the lower
two thirds of a left humerus (fig.13). The outline of asection through the broadest
part of the distal and of the humerusis given to the left of fig. 13, to exemplify the
difference in the proportions of this bone from the humerus of the Plesiosaurus
pachyomus from deposits of the same age. The outline connected by dots with
fig. 12 represents a section of the proximal end of that femur. I think it
most probable that both these bones appertain to the Plesiosaurus neocomiensis
of Campiche.

PLESIOSAURUS LATISPINUS, Owen. Cervical vertebre, Tab. VII; cervical and dorsal
vertebre, Tab. VIII; ilium and _ coracoid,
Tab. IX.

This species was founded on the characters of the two cervical vertebra figured
in Tabs. VII and VIII. They form part of a scattered series of about a dozen
vertebrae, with ribs, scapulz, portions of the coracoid bones (Tab. IX, fig. 2), an
ilium (Tab. IX, fig. 1), and a few other parts of the skeleton, included in a rock of
the ‘‘Shanklin-sand” or Lower Green-sand series, from the so-called “ Iguanodon
Quarry,” at Maidstone, Kent, where they were observed and partially wrought out

CRETACEOUS FORMATIONS. 15

by the proprietor, Witu1am Harpine BenstED, Esq., to whom the earlier discovery
of remains of an Iguanodon in the same locality and formation, is due.*

My first knowledge of these remains was obtained from plaster casts of the two
most complete vertebree which were transmitted to me by Mr. Bensted for deter-
mination of the species in 1853, which casts were afterwards presented by Mr.
Bensted to the Museum of the Royal College of Surgeons. ‘The original of these
casts, with the other portions of the skeleton discovered by Mr. Binsted, have since
been purchased by the Trustees of the British Museum.

From the Plesiosaurus pachyomus, Owen, of the Upper Green-sand of Cambridge-
shire, the present species differs in the greater relative length and breadth of the
centrum in proportion to its height, in the smaller relative size of the costal surface,
its greater prominence, and inferior position upon the side of the centrum, where
it is supported by a low parapophysis (compare Tab. VII with Tab. XX, tom. cit.,
Monogr. Cretaceous Reptiles). In that plate are represented the centrums of
three cervical vertebrz of the Plesiosaurus pachyomus ; one (fig. 1) giving the charac-
ters of the ordinary or more numerous cervicals; a second (fig. 2) showing the
commencement of the rise of the costal surface, and the development of the
vertical ridge connecting it with the neurapophysial surface ; a third (fig. 3) showing
the junction of the two articular surfaces indicative of the passage of part of the
head of the pleurapophysis upon the base of the neurapophysis.

The following are dimensions of an ordinary cervical centrum of the two species :

Plesiosaurus latispinus Plesiosaurus pachyonus.

Tn. lines. In. lines.
Length. . : . 0 anes : 2 8 ee Til
Breadth . 7 9 : 4 x i ; BO) | 9.3}
Height 0 6 3 . ; B # : 26 mB}
Fore-and-aft diameter of the costal surface . 5 Th) il al

The borders of the terminal articular surface are thinner and more defined in
Plesiosaurus latispinus than in Plesiosaurus pachyomus. ‘The costal surface (Tab. VIL,
fig. 1, pl) is longitudinally coextensive, in Plestosaurus latispinus, with little
more than one third of the fore-and-aft extent of the centrum. In Plesiosaurus
pachyomus it is coextensive with two thirds of the same extent. In Pleszosaurus
latispinus it is situated so low down as, in a direct side view, to mask part of the in-
ferior contour of the centrum. In Plesiosaurus pachyomus it allows the whole of the
lower contour to be seen in the same side view. In Plestosaurus latispinus more than the
vertical diameter of the costal surface, by one fifth or one sixth, intervenes between it

* See ‘Monograph on the Fossil Reptilia of the Cretaceous Formations, volume of the Paleeonto-
graphical Society for 1851, p. 105.
+ See ‘ Descriptive Catalogue of the Fossil Reptilia and Pisces,’ 4to, p. 63, No, 251,

16 FOSSIL REPTILIA OF THE

and the neurapophysial surface. The terminal articular surface (ib., fig. 3) is very
little concave, sububundulating, with a transversely elliptical, very shallow, central
depression. The sides of the centrum are slightly concave, the under surface more
feebly so, and it is not longitudinally ridged. The venous foramina are divided
by a transversely convex tract of 6 lines extent (Tab. VII, fig. 2). ‘The whole of the
non-articular surface is smooth. The costal surfaces (fig. 1, pi) are almost wholly
situated in the posterior half of the centrum. The neural arch and spine, by rare
fortune, are preserved in the present instance (fig. 1) in natural articulation with
the centrum. The sutural line describes a subangular convexity downwards, and
with the lowest part (np) nearer the anterior surface of the centrum. The neurapo-
physis, as it rises, has its fore-and-aft extent decreased by emarginations, of which
the posterior one is the longest; this extent then increases by the development of
the zygapophyses, of which the posterior (?’) is most raised ; but the anterior (7) most
produced. The spinous process (xs) is remarkable for its antero-posterior extent,
preserving the same width to its truncated summit; it thus presents a subquadrate
figure, and is inclined rather forward ; it arises from the entire fore-and-aft extent
of the median line of the neural arch. The total height of the vertebra, from the
under part of the centrum to the summit of the spine, is 9 inches; the height of
the spine itself is 45 inches; the antero-posterior diameter is 23 inches. The
articular surfaces of the prezygapophyses (2) look upward and a little inward ;
those of the postzygapophyses (z) look in the opposite direction.

Two other cervical vertebree, with the characters above defined, are preserved in
the slabs of stone exhibiting the parts of the skeleton of the same individual Plesiosaur.
In the last cervical vertebra(Tab. VIII, figs. 1 and 2) the costal surface is of large size,
especially in the vertical direction, and is supported inits lower third upon a parapo-
physis (»), which has now risen to the middle of the side of the centrum, and has come
in contact with a diapophysial development (d) of the side of the neural arch, support-
ing the upper two thirds of the costal surface. Together they form a thick and deep
outstanding process, 2 inches in vertical by | inch 3 lines in transverse extent, with
the articular surface for the expanded head of the rib looking outward and rather
downward, fig. 2. The terminal articular surface of the centrum (fig. 2, -) presents
a sharper or better defined border than that of the normal cervical vertebra
(Tab. VII, fig. 3) ; it is 3 inches 6 lines in transverse, and 2 inches 8 lines in vertical
diameter, almost an ellipse in figure, but with the lower curve greater or deeper
than the upper one; the central shallow depression is continued in the present
vertebra, of similar proportions and contour as in the foregoing normal cervical
vertebra. The neural arch has become anchylosed to the centrum, but the
greater part is broken away. The neural canal (x) is subcircular, 8 lines in
diameter.

CRETACEOUS FORMATIONS. 17

In the dorsal region, where the rib is supported wholly by a diapophysis
developed from the platform of the neural arch (np), the centrum has assumed the
ordinary subcircular shape, at least at its articular ends (Tab. VIII, fig. 3). The
surface is very slightly and uniformly concave in most, with a slight central
depression occupying about one third of the vertical diameter of the surface; but
in some, as in fig. 3, there is hardly any trace of the median depression. The
sides of the centrum are rather more concave lengthwise than in the cervical
series, but least so at the lower part.

The following are dimensions of the dorsal vertebra:

Plesiosaurus latissimus.

In. _ lines.
Length of centrum 2 6
Breadth of ditto, at articular So e101
Breadth of ditto, at the middle 2 4
Height of ditto, at articular end BAD)
Vertical diameter of outlet of neural canal 0 10

The following are admeasurements of a dorsal vertebra, having a greater .
proportion of the neural arch preserved :

In. lines.

Length of centrum . 2 8
Depth of terminal surface 20
Breadth of ditto 3
Breadth of the middle of the contin 2 5
From the under part of the centrum to the upper att of the

diapophysis . 2 . , 5 0 3 6 : 4 3
From ditto to summit of hears spine D 3 ; . : : 8 0
Fore-and-aft extent of neural spine . : 5 0 : 6 0 2 3

The chief changes observed in the middle dorsal vertebre are the almost
circular contour of the articular ends of the centrum, and the minor antero-
posterior breadth of the neural spine.

Of one of the dorsal ribs an extent of fourteen inches in length is preserved ; it
shows two flexures ; the first and shortest is concave upward, the rest convex
upward and outward, for half the extent of the rib, the rest being straight. Many
smaller parts of the ribs are scattered about the block of matrix.

The coracoids exhibit the proportional size, and broad expanse, characteristic
of the genus; they are in too fractured and mutilated a state to serve for deter-

mination of any specific characters. One of the largest portions is figured in
Tab. IX, fig. 2

18 FOSSIL REPTILIA OF THE CRETACEOUS FORMATIONS.

The ilium, five inches in length, and one inch in breadth at the middle, expands
to both extremities by outgrowth from one and the same margin, which is thus
made concave, whilst the opposite margin is nearly straight (Tab. IX, fig. 1). The
upper expanded end is obliquely truncate. The lower one shows the articular
facets contributed to the acetabulum, and to the other pelvic bones entering into
the formations of that articular cavity.

TAB. I.

Plesiosaurus planus, nat. size.

Side view of centrum of an anterior cervical vertebra.

. Front view of ditto.

Upper view of ditto.

. Under view of ditto.
. Side view of centrum of a posterior cervical vertebra.
. Front view of ditto.

. Upper view of ditto.

Side view of centrum of a posterior cervical vertebra.

. Under view of the same centrum as fig. 7.
. Side view of centrum of the first dorsal vertebra.
. Front view of ditto, with portion of the lower valve of Dianchora striata

attached.

. Side view of centrum of a dorsal vertebra.

. Front view of ditto.

. Upper view of ditto.

. Lower view of ditto.

. Side view of centrum of anterior caudal vertebra.

. Front view of ditto.

. Upper view of ditto.

. Under view of ditto.

20. Front view of centrum of third (?) cervical vertebra.
. Upper view of ditto.

. Side view of ditto.

. Side view of centrum of fourth (!) cervical vertebra.
4. Front view of ditto.

. Under view of ditto.
. Front view of centrum of a dorsal vertebra, with grooved articular surface.

From the Upper Green-sand near Cambridge. In the Woodwardian and

British Museums.

PLESIOSAURUS PLANUS

i
ee oy

TAB. IL.

Plesiosaurus planus, nat. size.

1. Front view of centrum of posterior cervical vertebra.

. Upper view of ditto.

: Front view of centrum of posterior cervical vertebra of a larger individual.
. Upper view of ditto.

. Side view of ditto.

. Under view of ditto.

2
3
4)
5
6. Front view of centrum of posterior cervical vertebra of a larger individual.
a
8. Side view of ditto.

9

. Upper view of ditto.

From the Upper Green-sand near Cambridge. In the Woodwardian and
British Museums.

6 Uf

a =

I.Dinkel del et ith. Wiest imp.

PLESIOSAURUS PLANUS.

TAB. IIT.

Plesiosaurus planus, nat. size.

1. Front view of a centrum from near the posterior part of the neck.

2. Side view of ditto.

. Upper view of ditto.

2

3

4. Under view of ditto.
5. Front view of centrum of posterior cervical vertebra.
6. Upper view of ditto.

7

. Upper view of anterior cervical vertebra, from an individual much larger than
the one to which the vertebra, Tab. I, figs. 1—4, belonged.

8. Front view of ditto, with the surface abraded.

9. Under view of ditto.

From the Upper Green-sand, near Cambridge. In the Woodwardian and
British Museums.

TSO,

‘W-West imp

TDinkel deLet Ith.

9, var. triganalis.

4, 7

figs 1.

7

PLANUS

PLE SIOSAURUS

10.

Ie

TAB. IV.

Plesiosaurus Bernardi, nat. size.

. Side view of centrum of an anterior cervical vertebra.
. Front view of ditto.

. Upper view of ditto.

: Under view of ditto.

. Side view of centrum of a cervical vertebra.

. Front view of ditto.

. Side view of centrum of cervical vertebra, slightly distorted by posthumous

pressure.

. Front view of ditto.

. Side view of centrum and base of neural arch of cervical vertebra.

Side view of centrum and base of neural arch of a succeeding cervical
vertebra.
Side view of centrum and neural arch, minus spine, of a cervical vertebra of a

larger individual.

From the Upper Green-sand, near Cambridge. In the British Museum.

J Dinkel. delet ith Wy

PLESIOSAURUS BERNARDI.

—

bo

D>

“I

TAB AVE

Plesiosaurus Bernardi, nat. size.

Front view of centrum and neurapophyses of cervical vertebra.

Back view of centrum and neural arch, minus spine, of cervical vertebra.

Front view of centrum and anchylosed base of neural arch of cervical vertebra
of a larger individual.

Under view of ditto.

Side view of ditto.

Upper view of the vertebra, fig. 2.

Under view of centrum of cervical vertebra, slightly distorted by posthumous

pressure.

From the Upper Green-sand, near Cambridge. In the British Museum.

TEVA

W-West imp.

J Dinkel del et ith.

PLESIOSAURUS BERNARDI

TAB. VI.
Plestosaurus neocomiensis, Cpche., nat. size.

1. Side view of centrum of cervical vertebra.
. Front view of ditto.
. Upper view of ditto.
. Under view of ditto.

. Side view of centrum of a posterior cervical vertebra.

2

3

4

5

6. Front view of ditto.
7. Side view of centrum of last cervical vertebra.
8. Front view of ditto.

9. Side view of centrum of a dorsal vertebra.

0. Front view of ditto.

1]. Upper view of ditto.

12: Femur, side view, with outline of distal end.

13. Lower part of humerus, with sectional contour of the expanded. portion.

From the Upper Green-sand, near Cambridge. In the Woodwardian and

British Museums.

UAL

Coates

W.West imp.

OCOMIENSIS, Cpche

Tal
G
a

N

PLESIOSAURUS

J.Dinkel del et lifh.

TAB. VII.

Plesiosaurus latispinus, nat. size.
Fig.
1. Side view of centrum of cervical vertebra.
2. Under view of ditto.

3. Front view of ditto.

Discovered by Mr. W. H. Bensted in the Lower Green-sand of the Iguanodon
Quarry, near Maidstone ; now in the British Museum.

J. Dinikel del et ith.

‘WWestimp.

PLESIOSAURUS LATISPINUS.

TAB. VIII.

Plesiosaurus latispinus, nat. size.

Fig.

1. Side view of centrum and part of anchylosed neural arch of a posterior cervical
vertebra.

2. Back view of ditto.

3. Front view of centrum and anchylosed neural arch, mutilated, of a dorsal

vertebra.

Discovered by Mr. W. H. Bensted in the Lower Green-sand of the Tguanedou
Quarry, near Maidstone ; now in the British Museum.

LT.V/V1.

J.Dinkel del. et ith WWest imp

PLESIOSAURUS LATISPINUS.

TAB. IX.

Plesiosaurus latispinus, nat. size.

Vig.
1. Right iliac bone.

2. Portion of left coracoid bone.

Discovered by Mr. W.H. Bensted in the Lower Green-sand of the [guanodon
Quarry; now in the British Museum.

JDmkel del. ct lith

Jed

BS

EID

IOSAURUS LATISPINUS

W.West imp

tt

Le ecto

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