LIZARDS. 573 



pterygoid and palatine, a stout os transversum or trans-palatine extends 

 outwards to the maxilla. In front of the palatines lie the small vomers, 

 which, in their turn, articulate with the premaxilla and maxilla, both of 

 which are furnished with small pointed teeth. In the posterior region 

 of the skull we have still to notice the large ex-occipitals with which the 

 opisthotics are fused, and which are continued into the conspicuous 

 parotic processes. The lateral walls of the brain case are largely formed 

 by the paired pro-otics. Internally, an important bone, the epipterygoid 

 or "columella" (not to be confounded with the columella or stapes of 

 the ear), extends from the prootic to the pterygoid. The orbit is bounded 

 posteriorly and inferiorly by the jugals. There is no ossified quadrato- 

 jugal, and thus the lateral temporal fossa is open below in the dried 

 skull (contrast Hatteria). The other fossse of the dried skull are the 

 supra-temporal on the upper surface, and the posterior-temporal on the 

 posterior face. 



Each half of the lower jaw is composed of six bones, which do not 

 fuse in the adult. 



The Limbs and Girdles. 



In the shoulder-girdle, the flat coracoids, with an anterior 

 precoracoidal region, articulate with the sternum, which is 

 represented by a cartilaginous plate of rhomboidal shape. 

 Over it projects the long limb of the T-shaped interclavicle, 

 which, at the sides, is continued backwards by the curved 

 clavicles. The remaining elements are the scapulae, which 

 are continuous with the cartilaginous supra-scapulse. 



The fore limbs have the usual parts. In the carpus all 

 the typical nine bones are represented, and there is in 

 addition an accessory " pisiform " bone. 



In the pelvic girdle, ilium, pubis, and ischium are repre- 

 sented as usual; there are both pubic and ischiac sym- 

 physes. 



In the tarsus the fibulare and tibiale are united, and the 

 distal row consists of only two bones. 



Nervous System. 



The brain consists of the usual parts. The cerebellum 

 is small and only partially overlaps the fourth ventricle. 

 In the region of the thalamus the epiphysis is distinct and 

 conspicuous, but in the adult the pineal body is quite 

 separated from it, and lies in its connective tissue capsule 

 below the skin. 



Alimentary Systetn. 



Small pointed teeth are present on the maxilte, pre- 

 maxillffi, palatines, and on the lower jaw ; they are attached 



