HO SYNOPSES AND DESCRIPTIONS. 



SOLENOGLYPHA. 

 BOTIIROPHERA. 



CKOTALIDAE. 



Stout, fusiforin; head large, distinct fruiu the neck; subti'iangular, 

 crown flat; tail short, with a rattle formed of horny rings, or tapering to 

 a point as in the Colubers. Pupil oblong, erect. A pit between the eye 

 and the nostril. Fangs tubular. Venom glands behind the eye at the 

 side of the skull. Scales keeled. Anal entire. 

 With a rattle; 



parietal shields scale-like ; frontal absent or divided 



Crotalus. 

 frontal and parietals present Sistrurus. 



without a rattle; 



frontal and parietals present Ancistrodon. 



crown-shields scale-like ; 



subcaudals in two rows except near entremity 



Lachesis. 

 subcaudals in two rows, rarely entire ; 



supi'aciliaries normal Trigonocephalus. 



supraciliary small, commonly Avith a row of small prom- 

 inent scales along its edge Teleuraspis. 



Crotalus. 



Linne, 1754. 



Tail terminating in a rattle. A deep pit in front of the eye. Top of 



tlu' liead covered with scales, with several larger plates in front, or, in the 



sul)genus C'rotalophorus, having parietals and frontals as in the Coluhridce. 



Anal entire. Subcaudals simple, a few of the posterior sometimes divided. 



Parietals and frontals scale-like ; 



nasal divided ; 



scales in 29 to 31 rows ; keels swollen or tubercular ; 

 a dorsal series of diamond-shaped spots 



durissus. 

 scales in 25 to 29 rows; keels not tubercular; 



a dorsal series of diamonds, varying to oblong subquad- 

 rangular spots or to transverse bands 



adamanteus. 



