120 GERRHOSAURID^. 



Tongue nearly entirely covered with imbricate scale-like papillae ; 

 no praofrontals ; frontoparietals present or absent ; lower eyelid 

 with a large transparent disk . . 3. Cordylosaurus, p. 126. 



II. Nostril pierced between two nasals, the rostral, and the first 

 labial ; ventrals not forming straight transverse series. 



A lateral fold along the body ; no frontoparietals. 



4. Zonosaurus, p. 127. 



No lateral fold on the body ; frontoparietals present. 



5. Tracheloptychus, p. 129. 



1. GERRHOSAURUS. 



Gerrhosaurus, IVicym. Isis, 1828, p. 378, and Herp. Mex. p. 11 ; 



Wcif/l. Syst. Amplt. p. 158 ; Gray, Cat. Liz. p. 52, and Froc. Zool. 



Sue. 18Gb, p. 042. 

 Cicigua, part., Gray, Griff. A. K. ix. Syn. p. G3. 

 Pleurotuchu,*, Smith, Mag. Zool. Bot. i. 1837, p. 142. 

 CTenliosauru.s, part., Dunt. i^- Bibr. v. p. 368. 



Nostril pierced between the first labial and two nasals ; pr£efrontal 

 and frontoparietal shields present. Lower eyelid scaly. A strong 

 lateral fold. Dorsal and ventral scales forming straight longitudinal 

 and transverse series. Subdigital scales smooth or tubercular. 

 Tongue entirely covered with rhomboidal papillae. 



Tropical and South Africa. 



Synopsis of the Sjtecies. 



I. Ventral shields in 14 or 16 longitudinal 



series ; tympanic shield large, cres- 



ccntic ; dorsal shields pluricarinate . 1. validus, p. 121. 



II. Ventral shields in 8 longitudinal series ; tympanic shield narrow ; 



dorsal scales uuicarinate. 



Praefrontals in contact, forming a long su- 

 ture ; dorsal shields in IS or 20 longi- 

 tudinal series 2. major, p. 121. 



Prajfrontals in contact, forming a long 

 suture ; dorsal shields in 24 to 28 

 longitudinal series, all keeled 3. niijrolineatus, p. 122. 



Praifrontals separated, the frontonasal 

 touching the frontal ; dorsal shields 

 in 20 to 24 longitudinal series, the 

 laterals not distinctly keeled 4. Jlaviyularis, p. 122. 



III. Ventral shields in 10 longitudinal 

 series ; tympanic shield large, cres- 



centic ; dorsal shields unicarinate . . 5. typicus, p. 123, 



