694 



PROF. OWEN ON THE RANK AND AFFINITIES IN 



the one hand, and of the Ophidia on the other, is the upper part of 

 the fore end of the skull. Cuvier has pointed out and illustrated 

 the characters of this region in existing species of both orders, to 

 which I add, for my present aim, the analysis and a figure of the 

 corresponding part of the skull in a species of the Ophidia. 



In this group, as exemplified in Python (fig. 13), the premaxillary 

 (22) constitutes the smallest element of the region in question. It is 

 a subquadrate or subtriangular ossicle, wedged into the fore part of 

 the vomers and nasals, touching behind the vertical wall formed by 

 the deflected median plates of the nasals (ib. 15), not interposed be- 

 tween the nasals, but contributing a little to the lower boundary of 

 the nasal apertures, which are parial and open obliquely upon 

 the fore part of the skull. The premaxillary is connected by elastic 

 ligaments with the fore ends of the maxillaries, not by suture with 

 those bones, which enjoy movements in the constricting serpents, 

 independent of the premaxillary. This ossicle, 22, in Python tigris 

 supports two teeth. 



Fig. 13. 



Fig. 14. 



Python. 



Upper surface of face. 



Varanus. 



In Lacertilia (fig. 14) the dentigerous part of the premaxillary (22) 

 answers to the whole of that bone in Ophidia ; but it is relatively 

 broader, contributes a greater proportion to the fore end of the 

 skull, and is immovably joined by suture, on each side, to the max- 

 illaries (2i). The most distinctive feature of the premaxillary is the 



