120 The Rev. W. D. Conybeare's Additional Notices 



These characters, when viewed collectively, present, as might have been 

 expected, an assemblage sui generis. Taken separately, they exhibit partial 

 approximations to the ichthyosaurus^ the crocodile, and the other lacertaB ; 

 nor is there any part of the structure of this new genus which may not be 

 paralleled from one of these three types. But I should be inclined to pro- 

 nounce (though not without hesitation) the approximations to the latter class 

 to be most close and important. 



In its general contour, the character of its temporal fossae, and the position 

 of its ossa quadrata, this genus resembles the lacerta iguana, &c. : but the 

 small size of the nostrils, the conformation of the palatal and pterygoidal parts 

 of the roof of the mouth (so far as the specimen enables us to judge of them), 

 and the dentition, remove it from this type. 



It agrees with the ichthyosaurus in the position and small size of the nos- 

 trils, and in the structure of the palatal and pterygoidal parts ; in which last 

 respect both the one and the other approximate to the crocodilian type ; but 

 it differs in the comparative shortness of its snout, which gives an entirely dis- 

 similar character to the whole contour of the head ; in carrying its teeth in 

 distinct alveoli instead of a continuous furrow ; and in all those points which 

 we have mentioned as peculiarly resembling the proper lacertian type. 



The only circumstances of peculiar analogy with the crocodile, are the den- 

 tition (as before stated) in distinct alveoli, and the distribution of the holes in 

 the maxillary bones giving passage to the branches of the maxillary nerve. 



Like the ichthyosaurus, then, this animal seems in a certain degree to have 

 blended the characters of the lacertian branch of Saurians, properly so called, 

 with those of the crocodile, and to have been in the same manner distinguished 

 from all recent Saurians by an inferior development of the olfactory organs. 



I proceed to a more detailed examination of the specimen represented in 

 Plate XIX.— 



Dentition. — The teeth are conical, very slender, curved inwards, finely 

 striated on the enamelled surface, and hollow throughout the interior; they 

 most nearly resemble those of the crocodile, but are still more slender : the 

 specimen being obviously a young individual, it is impossible to determine 

 whether the teeth continue hollow in age, nor are there any appearances 

 which indicate the manner in which the secondary replace the primary teeth. 

 The eight anterior teeth are considerably larger than the rest. 



Lower jaw. — The dental bone (m), although well exhibited in this head, is yet 

 so much more perfectly displayed in the larger specimen, figured in PI. XVIII. 

 that we have only to refer to our description of that specimen. 



The opercular bone may be seen as a lamina lining the interior of the dental. 



