212 THE CLASSIFICATION OF THE OPHIDIA. 



No flounces ; calyces moderately fringed ; nostril surrounded by scales and a supranasal ; no supraocular 



nor nasal horns Bitis Gray. 



Flounced ; spines below flounces ; apex with calyces not fringed ; nostril surrounded by scales and a 



supranasal, some of which are produced into horns Clotho Gray. 



aa. Apex of hemipenis spinous. 



Nostril surrounded by scales and a nasal ; horn-like supraocular scales Cerastes Wagl. 



II. Urosteges one-rowed. 



Body and tail cylindric Eclds Merr. 



Body and tail compressed and prehensile Aiheris Cope. 



I am unacquainted with the penial structure of the last two genera. 



Crotalidae, 



Two subfamilies are readily distinguishable, viz. : 



No jointed caudal appendage Coplriinm. 



A jointed caudal appendage Crotalinm. 



COPHIIN^E. 



/?. Urosteges two-rowed. 



Top of head scaled ; urosteges four-rowed at end ; a caudal spine Laahesis Wagl. 



Top of head with small scales ; tail normal * C'opJdas Merr. 



Top of head with large imbricate shield-like scales Peltopelor Gthr. 



Top of muzzle scaled ; rest of head shielded Hypnale Cope. 



Top of head with nine shields ; scales carinate Trigonoeephalus Oppel. 



Top of head with nine shields ; scales smooth C'alloselasma Cope. 



j3fi. Urosteges one-rowed. 



Body and tail cylindric, not prehensile ; head scaly Bothriopsis Pet. 



Body and tail compressed, prehensile ; head scaly, scales normal BoihriecMs Pet. 



As Bothriechis, but a horn-like produced scale over eye Ophryacus Cope. 



Body and tail compressed, prehensile ; head scaly ; a row of scales outside the superciliary shield. 



Ttleuraspis Cope. 

 Body and tail not prehensile ; nine normal head-shields Ancistrodon Beauv. 



The genera of the above series which I have examined are Cophias, Trigono- 

 eephalus, Ophryacus, Bothriopsis, Teleuraspis and Ancistrodon. In all, the hemipenis 

 is calyculate, excepting in Ancistrodon ; here it is flounced above the spinous region, 

 with a tendency to form calyces next to the sulcus in A. piscivwus. In Trigono- 

 eephalus (Halys) Mmalayanus the calyces are not fringed and are restricted to the 

 distal portion of each branch. 



CKOTALIN^. 



Only two genera of this subfamily are known. 



Head with nine normal shields Crotalophorus Gray. 



Head scaled above ., Crotalus Lim. 



* Bothrops Wagl., Trimesurus Lacep. Peters. 



