LACERTILIA. 



339 



cipital, prootic and opisthotic) is prolonged outwards into 

 parotic processes (as in the Chelonia), to the outer end of which 

 the quadrate is articulated (usually moveably). There is a small 

 bone at the outer ends of these processes, called the supra- 

 temporal (14). There are no alisphenoids, orbitospheiioids, 

 or presphenoids ; this part of the skull wall being mainly mem- 

 branous with tracts of cartilage. There is in all, except the 

 Amphisbaenidae and Chamaekonidae and the genus Anniella, a 

 rod-shaped bone the epipterygoid extending from the parietal 



St 



FIG. 185. Sternum with ribs and shoulder girdle of A, Iguana ; B, Lophiunis ; C, Platydacty- 

 L_ lus. St sternum ; ep interclavicle (episternum) ; Mst posterior prolongation of sternum 

 i carrying sternal ribs ; Co coracoid ; Cl clavicle ; Cr sternal crest ; X posterior continuation 

 of sternum without ribs (xiphisternum) (from Gegenbaur). 



to the pterygoid on each side, in close contact with the mem- 

 branous or cartilaginous wall of the skull (23)- This bone is some- 

 times called the columella cranii which is a bad name because 

 it leads to confusion between it and the columella auris. Those 

 lizards which possess it have been called the Kionocrania. There 

 is a small ossification in some Chelonia between the descending 

 process of the parietal and the pterygoid which seems to corre- 

 spond to it. The occipital condyle is mainly formed by the 

 basioccipital but the exoccipitals participate. It is double in 

 the Amphisbaenidae. The opisthotic is fused with the exoccipital 

 and the epiotic with the supraoccipital. the prootic remaining 

 separate. The parietals are not joined suturally to the 



