204 Huxley — New Fossil Reptiles. 



Bed D, — Existing land shells, casts of existing marine shells, vertebrae of shark, 



claw of crustacean, bone of land animal, existing marine shells and fragments. 

 Beds E, and F, are unfossiliferous. 

 Bed G, contains existing marine shells 220 feet ("sec. in Mr. McKay's MS., at p. 202 



he says 800 feet' ) above the present sea-level. 

 Bed H, yielded teeth and tusks of Hippopotamus; stone ring used by Bushmen. 



(They are wedged on to the pointed sticks as make-weights to assist in digging 



up roots.) Lastly. Fragments of native pottery." 



The specimen represented of the natural size in PI. XII. Fig. 1, 

 is from Bed a, and is the fossil marked No. 9 in Mr. McKay's list. 

 It is a shattered lacertilian skull having very much the general 

 shape of that of Jthynchosaiirus, being very broad posteriorly owing 

 to the large size of the supratemporal fossa (a), and tapering 

 anteriorly. The extremity of the snout is broken off. The large 

 orbits {h) looking almost directly upwards, lie in the anterior half of 

 the cranium, and are separated by a relatively narrow interorbital 

 space. What appears to be a parietal foramen is situated in the sagittal 

 suture near the truncated occipital margin of the skull. The 

 mandible is very much broken, but what remains of it shows that 

 it was remarkably thick, and that it was provided with teeth, the 

 best preserved of which is represented of twice the natural size in 

 Fig. 1 a. Eight or nine such teeth can be counted in relation with 

 the left ramus of the mandible between d and d. Each of these 

 teeth is straight, flattened from side to side in the crown, but more 

 cylindrical in the fang, and contains a pulp cavity, which extends 

 nearly to its summit, and is wide in the crown of the tooth. The 

 anterior edge of each tooth is like its surface, smooth and rounded, 

 but the posterior is produced into relatively strong and long denti- 

 culations. 



The ramus of a mandible of the same animal, is represented of 

 twice the size of nature in Plate XII. Fig. 2. From the arrangement 

 of the teeth in this and in the foregoing specimen, it appears that they 

 were not disposed in distinct alveoli, but lay close together in a 

 groove of the bony substance of the jaw. The symphysial end of 

 the ramus (a) seems to have been devoid of teeth. 



The successional teeth are well seen in various stages of develop- 

 ment at the bases of those which are fully formed. Most of the 

 latter have been split, or ground down, so as to show their pulp 

 cavities. I propose to name this new Lacertian Pristerodon McKayi. 



Fig. 3, PI. XII. is a figure, of the natural size, of another incom- 

 plete mandible, similar in its stoutness, and in the apparent absence 

 of teeth from the symphysial region, to the foregoing. But the 

 transverse sections of the fangs of the teeth, which have been ex- 

 posed, apparently by taking a slice for microscopic purposes, are 

 oval, and show that the pulp-cavity is almost obliterated. The teeth 

 increase in size from behind forwards, and a thin bony septum 

 between the first and second gives rise to a complete alveolus for the 

 first tooth. 



The inner side of the ramus gives off a singular slender bony 

 process, which may correspond with the flat and slender plate of 



