CROCODILIANS, LIZARDS, AND SNAKES. 225 



** No transverse gular fold; occipital shield .small. 

 t A gulai' appendage. 



Body comjiressed TropidodavtjiJus Boiileiigi;!'. 



tt No gular appendage. 

 \ Males with anal pores. 



Dorsal scales smooth and Juxtaposed Helocephahis Philippi. 



Dorsal scales keeled and imbricate Liohvmus ^^'iegmanu. 



II No anal pores. 



^ Caudal scales forming verticils. 

 Abdominal ribs; dorsal and ventral scales large and keeled. 



Scarfisciis Cope. 



No abdominal ribs Stenoccrus Dumdril and Bibrou. 



§§ Caudal scales not forming verticils. 

 No abdominal ribs; body slightly depressed; head-scales, small and 



keeled Saccodeira Girard. 



Abdominal ribs; body more or less compressed LiocephaJus Gray. 



h Infradigital lamelhe smooth or indistinctly keeled. 

 a A transverse gular fold; no anal pores. 

 *Body, cylindrical or feebly compressed. 



A slight dorsal crest or denticulation Enyalius Wagler. 



No crest; dorsal scales unif(jrm, granular, 



Urostrophus ' Dumcril and Bibrou. 

 * * Body depressed ; no dorsal crest. 



Lateral teeth, tricuspid Liosauriis Dumoril and Bibron. 



Lateral teeth with obtuse and subspherical crowns . . Diplohrm us Bell. 



fJ No gular fold ; male with aual pores Cfenoblepharis Tschudi. 



y No gular fold; no aual pores Apiychohrmus Boulenger. 



2. Premaxilhiry teeth, tricuspid. 



Body much depressed Phijmatiints Gravenliorst. 



B. Femoral pores present. 

 1. VertebrtB with zygosphenal articulation. 

 * Premaxillary teeth, tricuspid. 



A gular fold Amhlyrhynclius Bell. 



No gular fold Conolophun Fitzinger. 



** Lateral teeth only, with denticulated crowns. 



a. A more or less developed crest or row of enlarged scales on vertel)ral line. 

 p. No horny combs on posterior digits. 



y. A comi)ressed denticulated gular pouch. 



Body compressed ; tail long with homogeneous pholidosis, 



I<iuava Lanrenti. 

 yy. Gular poucli, if present, not crested. 



A gular iiouch ; tail long, not spinous Brachylophiis Cuvier. 



A gular pouch ; tail spinous .-it base Ctenosaiira Wiegmann. 



A gular pouch ; tiiil spinous to end Cachryx Cope. 



No gular pouch; a transverse collar; tail not spinous. 



Dijisoaannifi II alio well. 

 /3/i. Horny combs on some of the poalerior digits. 



A gular pouch; tail spinous at base Cychira- Harlan. 



aa. No dorsal crest of scales. 



Superciliarj^ scales segmental; tail without s])iues; a gular fold. 



Sattrovialiis Dumdril. 



' Including Jviaolepis Boulenger. 

 - Including Metoporents Wagler. 

 NAT MUS 98 — 15 



