698 



PROF. OAVEN ON THE EANK AND AFFINITIES IN 



lizard (Amblyrhynchus) agrees with the rest of the Iguanidce and 

 some other Saurians. 



The main distinction of the pterygoids in the great extinct Sea- 

 lizard (fig. 16, 24) is their extensive median suture, by which these 

 bones have their fixity more assured, and contribute a greater share 

 to the roof of the mouth. It is probable that observation of this 

 character may have led Prof. Cope to reject thedetermination by 

 Cuvier of the pterygoid nature of these bones, and to propound 

 their homology with the palatine bones of the Beptilia, and espe- 

 cially with those in Ophidic/, (fig. 17), in which these bones, 20, as 

 well as the pterygoids, 24, support teeth. 



Python. 

 The bony palate. 



The narrow fore end of the ophidian pterygoid (fig. 17, 24) 

 articulates by a squamous suture with the palatine (ib. 20) ; a similar 

 suture attaches the low outer angle to the " transversal " or 

 ectopterygoid, 25, and the opposite inner one to the pterapophysis 

 of the basisphenoid. The elastic connecting tissue allows some 

 yielding motion at all these joints. There is no trace of a colu- 

 mellar articular process on the upper part of the bone in any 

 Ophidian, nor is there a trace of the " columella." The long hinder 

 extension of the tympanic process, Z, so characteristic of the ptery- 

 goid bone, is as well developed in Ophidia as it is in Lacertilia ; 

 but it is more bent in Python than in Amblyrhynchus or in Mosa- 

 aaurus. 



The true palatine bone in Mosasaurus (fig. 16, 20) is edentulous, 



