1 825.] Mr, Gray on the Genera of Reptiles. 205 



^With a Rattle, 

 J 1. Crotalus, Lzw. 



Head covered with scales ; the muzzle perforated with a small 

 fovea behind each nostril ; tail furnished with aratthng appendix 

 formed by the dry terminal scales. America, 



C. horidus, Lin. 



2. Crotalophorus, L/?7. Gray, 



Head covered with plates ; muzzle with a small fovea behind 

 each nostril ; tail furnished with a rattling appendix. America. 

 C. miliaris, Lin, 



'^^ Without any Rattles. 



3. EcHTs, ilferrew. Scytales, jL«^r. not Grono?;. 



• Head covered with scales ; the muzzle not perforated ; tail 

 simple. AUied to Viperadae, Merrem. 



S. zic zac, Daud, Boa horrata, Schneider, 



4. AcANTHOPis, Daud, Ophyas, Merrem, 



Head with large scales in front ; no pores behind the nostrils ; 

 tail with double plate only beneath the end, which terminate in a 

 very acute point. 



A. cerastinus, Daud. Boa palpebrosa, Shaw, Ophryas 

 Acantophis, Merrem, ■ , 



5. Langaha, JBrwg. Langaya, 67mt(;. 



Head covered with large plates ; muzzle long, pointed ; tail 

 surrounded by ring-like plates, except at the end which is scaly. 



L. nasuta, Shaw. L. madagascariensis, Me/rem. Is this 

 genus allied to Dryinus ? 



Fam.W. ViPERiDiE. 



The body scaly ; the abdomen covered with annulated plates ; 

 the tail with divided scale beneath ; anus without spurs. 



Head distinct, scaly, behind broad. Viperina* 



1. Trigonocephalus, Oppe/. Lachensis, JD^mc?. Cophias 

 Merrem. . 



Head triangular with a distinct fovea behind the nostrils; tail 

 round ; apex simple, conical, sometimes armed. 



T. atrox, Merrem. . .^ 



2. Crasedocephalus, Kuhl. BothVops, Wagle'r. 



Head truncated, with a distinct fovea behind each nostril ; tail 

 round, the plates towards the anus entire, apex simple, conical,, 

 plates halved. 



C. cTotSilinm, KnhL Crotalus Mutus, Lz/z. 



3. Cobra, Laur. Vipera, Lciur, Echidna, Merrem,not Geoff, 

 Head covered with scales without any fovea behind the nos- 

 trils ; tail round. ^^ 



V. Cera&tes, Laur, Coluber Cerastes^ Lin. 



