SYNOPSES AND DESCRIPTIONS, 11 1 



scales in 23 to 25 rows ; 



a dorsal series <>f iiu>re or less irregular and broken 

 transverse bands horridus. 



nasals undivided ; 



supraciliary produced as a sort of horn ; 



scales in 21 to 23 rows cerastes. 



" supraciliaries and other lai'ge plates smooth" 



lejjiilus. 



nasals divided; 



scales in 21 to 23 series, slightly carinate 



tigris. 

 scales in 23 to 25 rows lugubris. 



parietals and frontals like those of the colubers ; 



scales in 23 to 25 rows cafenatus. 



scales in 21 to 23 rows miUarim. 



Crotalus durissus. 



Linnc, 1758, Sust. Nat., cd. X, I, 214. 



Stout, elongate, fusiform ; belly broad ; head large, triangular, tail short, 

 thick, with more or less acuminate rattle. Eye small. Internasals tri- 

 angular. Frontals two pairs. Scales of occiput and temples keeled. 

 Rostral touched by six plates. Two anteorbitals ; upper large, quad- 

 rangular; lower elongate, narrow, sometimes crowded from the orbit. 

 Two lorcals. Five small orbitals beneath and behind the eye. Three 

 (2—5) rows of scales between suborbitals and hxbials. Labials 13 — 16, 

 first and fiftli rather larger; infralabials 14 — 18. Sulmientals one pair, 

 large, or, through division of the anterior pair of infralabials, two pairs, 

 anterior small. Scales lozenge -shaped, with strong swollen keels, in 

 29 — 31 rows, outer broader, outer row smooth. Ventrals broad, 175 — 

 183+19—33 (175—1994-19—33.) 



Yellowish-brown. A light-edged dark band across the head, through 

 the eyes to the angle of the mouth. A similar l)and of dark brown from 

 the head behind the supraciliaries on each side of the neck. These are 

 followed by a dorsal series of 25—27 (25—30) diamond-shaped spots of 

 brown, with lighter center and yellow borders occujiying single rows of 

 scales. The borders continue upon the flanks there inclosing rhombs 

 of the ground coloi*, and below them a series of half-rhombs which filter- 



