48. CROTALUS 919 



the mouth. The scales behind and above this light stripe 

 are darker than the ground color and are set off posteriorly 

 by a light streak which runs down and back from the corner 

 of the eye and strikes the supralabials in front of the corner 

 of the mouth. The tail is whitish or grayish with about four 

 to six black cross bands or rings. The lower surfaces are 

 yellowish white, sometimes clouded with brown. 



Length to anus 568 745 789 897 923 932 



Length of tail to base 



of rattle 31 48 50 67 70 70 



Distribution. This rattlesnake probably is confined to 

 Tortuga Island, in the Gulf of California, Mexico. 



Remarks. This species resembles C. atrox rather than 

 C. exsul and C. lucasensis. The first labial rarely is divided 

 and the coloration is of the punctulate type as in C. atrox. 

 The pattern of the dorsal rhombs is quite different. 



This rattlesnake was common on Tortuga Island. Eight- 

 een were collected in two days and others were seen. Three 

 were taken at the foot of an old osprey's nest built about 

 the base of a great cactus. All of the snakes were extremely 

 fat and most of them contained from two to four mice. Most 

 of them were more or less hidden in little cups in the ground 

 and had debris or blocks of lava over them. However, 

 they usually rattled vigorously on one's approach, making 

 it easy to find them. 



211. Crotalus exsul Carman 



RED DIAMOND RATTLESNAKE 



Plates 99 and 109 



Crotalus exsul CARMAN, Mem. Mus. Compr. Zool., Cambr., Vol. VIII, 

 No. 3, 1883, pp. 114, 174 (type locality, Cedros Island, Lower 

 California), VAN DENBURGH, Proc. Cal. Acad. Sci., Ser. 3, Vol. 

 4, No. i, 1905, pp. 3, 24; VAN DENBURGH, Proc. Cal. Acad. Sci., 



