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 
otra = ol 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 Garman 
Rep Diamonp RaTTrLEsSNAKE 
Plates 99 and 109 
Crotalus exsul Garman, Mem. Mus. Compr. Zool., Cambr., Vol. VIII, 
No. 3, 1883, pp. 114, 174 (type locality, Cedros Island, Lower 
California), Van Densurcn, Proc. Cal. Acad. Sci., Ser. 3, Vol. 
4, No. 1, 1905, pp. 3, 24; Van Densurau, Proc. Cal. Acad. Sci., 
