REPTILES. 



321 



sanrus. All the species belong to the old world. Helodermid^, pleu- 

 rodont; tongue with papillae at base ; no femoral pores. Heloderma, with 

 two species, horridum and suspeciu/n, from the Mexican region, contains 

 the only poisonous lizards. Teid^, 

 acrodont, tongue two-pointed, covered 

 with imbricate scales ; tympanic mem- 

 brane visible ; usually two transverse 

 folds on throat. Limbs present, rarely 

 rudimentary. About 70 American spe- 

 cies. Cnemidophorus, with rounded tail, 

 eyelids developed, small scales and large 

 ventral plates, includes the six-striped 

 lizard (C sexlineatus') of the eastern 

 U.S. Tejus teguixin of Central Ameri- 

 ca reaches a length of 6 or 7 feet. 



Section V. ANNULATA. Body 

 covered by quadrangular scales, ar- 

 ranged in rings around the body. Body 

 vermiform, limbless, or with small fore 

 limbs. Teeth acrodont or pleurodont, 

 no palatine teeth ; tongue short, thick, 

 non-protrusible ; eyelids and tympanic 

 membrane lacking. About 50 species, 

 half of them belonging to Amphisbi^na. 

 All the species tropical or subtrojjical ; 

 they live burrowing in the earth, and 

 feed especially on insects and worms. 



The Lacertilia are poorly represented as fossils, the group appearing in 

 the cretaceous. IVIost of the fossils are referred to existing families, but 

 the Dolichosauria from the cretaceous of Europe, differ from all recent 



Fig. 315. ^\\x\\ oi Heloderma, 

 after GUnther. /, frontal ; y, jugal; 

 in, maxillary ; n, nasal ; p, parietal ; 

 ff, postfrontal ; pr, prefrontal ; pt, 

 pterygoid; px, premaxillary ; s, 

 squamosal ; so, supraoccipital. 



Sub-Order 2. Pythonomorpha. 



Large, extinct, extremely elongate reptiles with four flipper-like extremi- 

 ties ; vertebrae procoelous, with or without zygantra and zygosphenes ; usu- 

 ally no sacrum ; supratemporal fossa present, jugal arch incomplete ; teeth 

 large, conic, acrodont, fused to maxillae and pterygoids ; a parietal foramen ; 

 both girdles present ; feet pentadactyl, without claws. 



The Pythonomorpha occur in the upper cretaceous of America, Europe, 

 and New Zealand. The vertebrae number more than a hundred ; the cer- 

 vicals bear strong hypapophyses, the caudals with chevron bones. The 

 skull was lizard-like, the cranial cavity being open in front. The parietals 

 are fused in the middle line, and were connected with the alisphenoids and 

 prootic by lateral processes. The quadrates are large, and are articulated 

 to a supratemporal. The premaxilla unpaired, the rami of the lower jaw 



