918 16. CROTAL1DSE 



2 1 0. Crotalus tortugensis Van Denburgh & Slevin 

 TORTUGA ISLAND DIAMOND RATTLESNAKE 



Crotalus tortugensis VAN DENBURGH & SLEVIN, Proc. Cal. Acad. Sci., 

 Ser. 4, Vol. XI, 1921, p. 398 (type locality, Tortuga Island, 

 Gulf of California, Mexico). 



Description. Large. Head broad, flat-topped, varying 

 in outline according to position of fangs. Rostral usually 

 higher than wide, in contact with anterior nasal. Two nasals. 

 Usually two preoculars and two to four internasals. A large 

 scale just in front of supraocular. Supraocular large but not 

 raised into a horn-like process; separated from its fellow 

 by from four to five irregular rows of scales. About 1 4 to 

 17 superior and 14 to 18 inferior labials; first pair of latter 

 usually meeting on median line in front of a single pair of 

 genials, but rarely divided. About three or four rows of 

 scales between supraoculars and eye. Scales in 27 rows, of 

 which one or two on each side are smooth. Gastrosteges 

 varying from 180 to 190. Urosteges 16 to 25. 



The general color is yellowish, brownish or pinkish, with 

 a series of large, darker brown blotches along the back These 

 blotches often are not well defined, especially posteriorly, 

 are not completely enclosed in light borders, and show much 

 of the punctulate or pepper-and-salt style of coloration. The 

 margins of the rhombs are much darker than the central por- 

 tions which usually include on each side a group of scales 

 as pale as the general ground color. These light areas in 

 the rhombs may spread and be connected across the middle 

 line. The sides are more or less indefinitely spotted or 

 blotched with dark brown in the same punctulate manner, 

 and sometimes show pinkish shades. The head is nearly 

 unicolor above or mottled with darker, with a light streak 

 across the supraocular plate. A yellowish or whitish stripe 

 runs across the side of the face from the preocular plates to 



