PROCEEDINGS 



OP THK 



CALIFORNIA ACADEMY OF SCIENCES 



Fourth Series 



Vol. X, No. 2, pp. 29-30, pi. 3 August 6. 1920 



II 



DESCRIPTION OF A NEW SPECIES OF RATTLE- 

 SNAKE (CROTALUS LUCASENSIS) FROM 

 LOWER CALIFORNIA 



BY 



JOHN VAN DENBURGH 



Curator, Department of Herpetology 



The first specimens of the diamond rattlesnake of the Cape 

 Region of Lower California were sent from Cape San Lucas 

 by John Xantus. Cope recorded them, in^861, as Caudisona 

 atrox sonoraensis, but remarked that they were more delicately 

 tinted than Sonoran specimens, the dorsal rhombs being more 

 perfect and their yellow borders brighter. A considerable 

 number of specimens have been collected in southern Lower 

 California in more recent years, and have been recorded usually 

 as C. atrox. The differences in coloration, however, seem to be 

 of such constancy as to make it desirable to regard the San 

 Lucan snakes as a species distinct from both C. atrox and the 

 reddish C. exsul. I, therefore, propose for this snake the name 



Crotalus lucasensis, new species 

 (Plate 3, fig. 1) 



Diagnosis. — Similar to C. atrox (Plate 3, fig. 2) but colora- 

 tion brighter, much less punctulate, and with dorsal rhombs 

 more completely enclosed in light borders. 



