CRETACEOUS REPTILES. 389 
different persons, and ultimately found their way to the two collections of which 
they are now respectively the ornaments. 
Assuming then the two groups of vertebrae to have belonged to the same 
skeleton, and the conformity in shape, and size of the vertebra and ribs, favour 
the conclusion which Mr. Dixon has drawn from the historical evidence, we 
may then enumerate fifty-seven vertebra between the skull and the pelvis, sup- 
posing that none have been lost between the end of the specimen in PI]. XX XVIII. 
and the beginning of that in Pl. XXXIX. Amongst existing Lacertians this 
number of abdominal (cervical and dorsal) vertebree is equalled only by those 
snake-like species (Pseudopus, Bipes, Ophisaurus) which seem to make the trans- 
ition 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 
fig. 1. Pl. XXXVIII., at 51 & 53, or so complete a sacrum and pelvic bones as 
are shown in fig. 4. Pl. XXXIX. Of those existing Lacertians which had the 
hinder extremities as well developed as in the extinct species under considera- 
tion, the greatest recorded number of vertebrae between the skull and the sacrum 
is forty-one*. 
Although the evidence relating to the discovery of the specimens (fig. 4. 
Pl. XXXIX. and fig. 1. Pl. XX XVIII.) is such as to lead me to deem it highly 
probable that they form the anterior and posterior moieties of the vertebre of 
the trunk of the same individual; yet, as it does not amount to absolute de- 
monstration, 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 fragment of 
skull, and the chain of thirty-six vertebree imbedded in one block of chalk and 
represented in Pl. XX XVIII. fig. 1. The most cautious and sceptical Paleon- 
tologist 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 displace- 
ment 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 dis- 
placement ; and taking, also, into consideration the gradual diminution of the 
* According to the table in Cuvier, Leg¢ons d’Anat. Comp. i. (1836) p. 221, e.g. in the Scincus 
ocellatus. 
ar 
