and relations to the pelvis, is, without doubt, the principal sacral vertebra. The impression which it has left appears to me to have been formed by the outer face of the right sacral rib. Certainly not more than one of the three succeeding vertebrae, the two hindermost of which are represented by little more than casts of their neural canals and of the region thereabouts, can have been united with the principal sacral vertebra to form the sacrum.
On clearing away the friable remains of the original bone from the hard sandstone matrix, the latter presents casts of the external surface and of the neural canal of each vertebra, which, in some cases, are very perfect. These casts show no sign whatever of the deep pits which would correspond with well- developed transverse processes ; but there is a depression at the anterior part of each body of a vertebra answering to what appears to have been a low tubercle for the attachment of a rib, as in existing lizards.
In correspondence with this structure of the vertebrae, the remains of a number of ribs, which have been laid bare by chiselling away portions of the matrix, show no trace of a division into capitulum and tuberculum at their vertebral ends. The longest of them is 4 inches in length. Like the rib of a Monitor , its vertebral end is somewhat expanded ; and it is so curved as to be, at first, a little concave towards the dorsal aspect ; in the rest of its extent it is convex in that direction.
I see no remains of true sternal ribs ; but there are numerous faint transverse linear impressions of a system of dermal ossifications, which I conceive, answers to the so-called " abdominal ribs " of a Crocodile, or to the corresponding structures in Sphenodon. These, however, are better shown in another slab.
To the anterior extremity of the block of sandstone which contains these vertebrae (and which I shall call No. 1) fits another, which bears the anterior cervico-dorsal vertebrae and the skull. The latter is bent round so that its axis is nearly at right angles with that of the body.
None of these anterior cervico-dorsal vertebrae can be clearly made out; but they cannot have been numerous, and I doubt whether there were altogether more than twenty, or twenty-two, presacral vertebrae.
The skull had a length, when complete, of not less than 7 inches. It is about 5 inches broad posteriorly, but anteriorly narrows to a deflexed and comparatively slender snout, the diameter of which is not more than 1 inch. It is so disposed as to turn its ventral aspect to the eye. The left ramus of the lower jaw is in place, though much mutilated. The right ramus is broken away, and shows the oral surface of the palate and maxilla, with the obscure remains of several obtusely conical teeth.
On the left side, a good deal of the dentary edge of the left ramus of the mandible is preserved, and it is seen to be shut against the upper jaw, passing on the inner side of a series of mutilated teeth, which are fixed on the maxilla. The end of the snout presents a very remarkable structure. The anterior portion of the edge of each
