SYNOPSES AND DESCRIPTIONS. Ill 



scales in 23 to 25 rows ; 



a dorsal series of more or less irregular and broken 

 trans verse bands horridus. 



nasals undivided; 



supraciliary produced as a sort of horn; 



scales in 21 to 23 rows cerastes. 



" supraciliaries and other large plates smooth" 



lejjidus. 

 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 catenatus. 



scales in 21 to 23 rows miliarias. 



Crotalus durissus. 



Linne, 1758, Syst. Nat, ed. 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 loreals. Five small orbitals beneath and behind the eye. Three 

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

 first and fifth rather larger; infralabials 14 — -18. Submentals 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—199+19—33.) 



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

 the eyes to the angle of the mouth. A similar band 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 occupying single rows of 

 scales. The borders continue upon the flanks there inclosing rhombs 

 pf the groivnd color, and below them a series of half-rhombs which alter- 



