SNAKES. 19 
Crotalus sp., Linn. S. N. Crotalus, § 2, Wagler, Syst. Amph. 
176, 1830. Gray, Zool. Misc. Uropsophus, Wagler, Syst. Amph. 
176, 1830. Gray, Zool. Misc.1842. Anat., Tyson, Phil. Trans. 4144. 
Duvernoy, Ann. Sci. Nat. xxvi. t. 10, f. 1—5. 
1. The Rarrie-snake. Uropsophus durissus. Crotalus du- 
rissus, Kalm. Act. Holm. p. 1752, 310, 1753, 52, 185. Linn. S. N. 
i. 372. Daud. Rept. v. t. 68, f. 1, 2. Schlegel, Phys. Serp. 
565, ¢. 20, f. 15, 16. Holbrook, N. Amer. Erp. iii. 9, t. 1. C. atri- 
caudatus, Latr. Rept. iii. 209. Gray, Zool. Misc. 51. C. horridus, 
Guerin, Icon. t. 23, f. 2. C. confluentus, Say. C. rhombifer, Latr. 
Rept. iii. 197. _C. triseriatus, Wiegm. in Mus. Berl. Uropsophus 
triseriatus, Wagler, Syst. Amph. 176. Gray, Zool. Misc. 51. Rattle- 
snake, Catesby, Carol. ii. t.41. Crotalus Catesbei, Hemp. Fitz. N. 
Class. 63. 
Pale brown; temple with a dark streak from the back of the 
eye; occiput and back of the neck with a brown spot on each side ; 
back with irregular brown cross bands ; sides with a series of roundish 
dark spots. 
a. In spirits. Young. N. America, Texas. From Mr. Drum- 
mond’s collection. 
b. In spirits. Young. N. America. 
c. In spirits. Adult. N. America. 
d. In spirits. Half grown. N. America, New Orleans. 
e. In spirits. Adult; discoloured. N. America. Presented by the 
Royal College of Surgeons. 
11. Crora.us. 
Head between and behind the eyes covered with convex keeled 
scales; nose in front of the eyes, with one (or rarely three) pair of 
shields: superciliary shields large; temples, cheeks and lores co- 
vered with small, uniform, convex scales ; upper labial shields very 
small, the first two and fourth on each side largest; lower labial 
shields larger,—the first, second, fourth and fifth largest, rest nearly 
uniform ; shields under the eyes small, like those on the temple, and 
in five or six series. 
Crotalus, Gray, Ann. Phil. 1825, 205. Crotalus sp., Linn. 
S. N. ed. 10, 214. Crotalus, Sect. I., Wagler, Syst. Amph. 76. 
Gray, Zool. Misc. 51. _Urocrotalon and Crotalus, Fitz. Syst. Oph. 
1846. Caudisona sp., Linn. S. N. ed. 1. Laur. Rept. 92. 
The best character between the two genera appears to be the 
size of the labial shield, and the size and number of the scales on 
