398 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



urosteges and the genials and gulars yellowish white with black 

 or dark brown margins. Superior labials 8-8. Scale rows 23. 

 Gastrosteges 228. Urosteges 63. 



Type. — California Academy of Sciences No. 50514; adult 

 male, collected by Joseph R. Slevin and Joseph C. Chamberlin, 

 on Santa Catalina Island, Gulf of California, Mexico, June 12, 

 1921. 



Crotalus tortugensis, new species 



Diagnosis. — Similar to Crotalus atrox, but with dorsal rhombs 

 differently marked. Margins of rhombs much darker than 

 central portions which usually include on each side a group of 

 lighter scales as pale as the general dorsal ground color. These 

 light areas in the rhombs may spread and be connected across 

 the back. The coloration suggests that of C. molossus, although 

 the light borders of the rhombs are very incomplete. 



Type. — California Academy of Sciences No. 50515; collected 

 by Joseph R. Slevin, on Tortuga Island, Gulf of California, 

 Mexico, June 22, 1921. 



