172 iGUANiD-a;. 



Dorsal scales nearly as large as ventrals ; 

 sides of neck with groups of erect 

 spinose scales 6. S2nnulosus, p. 175. 



B. No dorso-nuchal crest. 



1. Dorsal scales keeled. 



Dorsal scales scarcely larger than ven- 

 trals ; enlarged supraocular scales not 

 occupying more than half the width of 

 the supraocular region 7. torquatus, p. 170, 



Dorsal scales scarcely larger than ven- 

 trals ; supraocular region nearly en- 

 tirely covered by a series of transverse 

 band-like scales 8. liygomi, p. 177. 



Dorsal scales at least twice as large as 



ventrals 9. hispidus, p. 177, 



2, Dorsal scales smooth 10. semitceniatus, p. 178, 



II, Nostril lateral ; ventral scales trica- 



rinate 11, blainvillii, p. 178. 



1. Tropidurus grayi. 



Leiocephalus grayii, Gray, Cat. p. 218. 

 Leiocephalus grayii, Bell, Zool. Bcarjle, Itept. p. 24, pi. xiii. fig. 1 . 

 Holotropis grayii, A. Dum. Cat. Meth. Rept. p. 70, and Arch. Mus. 



viii. p. 538. 

 Craniopeltis grayii, Peters, Mon. Berl. Ac. 1871, p. 645. 



bivittata, Peters, I. c. 



Tropidurus ( Craniopeltis) gravii, Steinilachn. Festschr. zool.-bot. Ges. 



Wien, 1876, p. 310, pi. ii. fig. 1. 



Upper head-scales smooth ; a series of five to seven transverse 

 band-like supraoculars, covering the greater part of the supraocular 

 region ; occipital as broad as or broader than the latter, usually 

 broader than long ; ear-opening with a more or less developed fringe 

 of pointed scales anteriorly. A strong curved antehumeral fold ; 

 sides of neck more or less strongly plicate, the folds forming a pouch 

 between the ear and the antehumeral fold. A dorso-nuchal crest, 

 well developed in the male, reduced to a mere serrated ridge in the 

 female. Dorsal scales large, much larger than ventrals, very 

 strongly keeled, ending in a mucro or spine ; the keels forming con- 

 tinuous slightly oblique longitudinal series; lateral scales smaller, also 

 strongly keeled ; ventrals smooth ; fifty-five to sixty-five scales round 

 the middle of the body. The adpressed hind limb reaches the ear, or 

 between the latter and the eye. Tail once and a half to once and 

 two thirds as long as head and body, compressed, especially in the 

 male, crested or serrated like the back. Olive above, spotted with 

 black ; sometimes a light yellowish band on each side of the back 

 and another from axilla to groin ; antehumeral fold black in the 



