156 



VERTEBRATE SKELETON 



halves uniting later and giving off an anterior rostrum which closes 

 the hypophysial fenestra. The squamosal is long and slender and 

 is moveably articulated with the quadrate. None have a quadrato- 

 jugal and the zygomatic is lacking in Amphisbaenans. 



The lower jaw has the normal six bones (fig. 151), distinct in the 

 young and persisting so in many genera, except that the goniale 

 fuses with the articulare. The teeth in both jaws are either acrodont 

 or pleurodont, and teeth also occur on the palatines except in aber- 

 rant genera. The hyoid apparatus varies; it always has a small 

 body, and supports two pairs of cornua and a well developed ento- 



FiG. 165. Fig. i66. 



Fig. 165. — Side view of skull of Chameleo (Parker, 'So), a, articulare; as. alisphe 

 noid; bs, basisphenoid; cr, coronoid; d, dentale;/, frontal; ip. interparietal; /, lacrimal 

 m, maxilla; os, orbital septum; p, parietal; po, postorbital; prf, prefrontal; pt, pterygoid 

 g, quadrate; sa, surangulare; so, supraoccipital; sq, squamosal; s, zygomatic. 



Fig. 166. — A, Hyoid apparatus of Heloderma. b, branchial cornu; c, hyoid copula 

 h, hyoid cornu. 



glossal process. The upper end of the adult hyoid has lost its con- 

 nexion with the columella and has moved backwards, and in Geckos 

 is connected with the otoccipital by a cartilage of uncertain 

 homology. The branchial arches, usually long, consist of one or two 

 articles, the halves of the second arch is some genera lying close 

 together and extending far backwards. 



Pythonomorpha. — These aquatic lizards of former days differ less from true 

 lizards in skull (fig. 167) than in other parts of the skeleton. Parietals, frontals 



