12 BAUR. [Vol. VII. 



basioccipital and basisphenoid in connection with the trans- 

 verse canal (can. hypo-basilaris, Dollo), These hypobasilar 

 canals are also present in Varanus. The basisphenoid is well 

 developed in front, and ending in a vertical plane, on the lower 

 face of which the parasphenoid extends in front. The basi- 

 sphenoid shows the following connections : basioccipital, petro- 

 sal, pterygoids. 



The Supraoccipital. 



This is a simple but large element. It is suturally united 

 with the exoccipitals, paroccipitals, and petrosals. It contains 

 on each side portions of the upper semicircular canals. It is 

 not in direct connection with the parietal, but separated from 

 it through cartilage or connective tissue. Above it fits into a 

 groove at the posterior end of the parietals. In shape it is 

 very much like the element in Varanus. It takes part in the 

 formation of the foramen magnum. 



The Exo-paroccipital (Figs. 20, 21). 



As in all Lacertilia, the paroccipital is co-ossified with the 

 exoccipital. The paroccipital processes are more developed, as 

 in Varanus, resembling these elements in Iguana. The exo- 

 paroccipital joins the following elements exactly as in Varanus : 

 supraoccipital, petrosal (the petrosal forming with the squamosal 

 the anterior portion of the paroccipital process), squamosal. The 

 lower and distal part of the paroccipital process joins the 

 quadrate. 



The Stapes. 



The stapes is a long and slender element, expanding grad- 

 ually at both ends. Its position was doubtless as in Varanus. 



The Petrosal (pro-otic). 



The petrosal resembles the same element in Varanus. It 

 shows the same emargination in front for the reception of the 

 trigeminus ; but the tendency is to form a regular foramen, 

 a small process projecting from its upper portion to surround 

 the nerve. The connections are the same as in Varanus : basi- 

 sphenoid and anterior portion of basioccipital, supraoccipital, 



