454 REPORT OF NATIONAL MUSEUM, 1893. 



after, Mr. E. W. Nelsou sent a specimen to the National Museum from 

 Tucson, Ariz., the one figured, and recently Dr. Tliimotby E. Wilcox 

 obtained it at Fort Huaclmca in the same Territory. How far it extends 

 south into Mexico we do not know. 



Habits. — Nothing is known about its habits except that it is a moun- 

 tain species, and as it is our smallest crotalus, its bite is probably i^ro- 

 portionately less dangerous than that of tlie others. 



TirE White Ratti-esnakr. 

 Crotalus MitchcUil,* Cope. 

 Plate 17. 



imi.—Caudisona MHcheUii, Cote, Proc. Pbila. Acad., 1861, p. 293.— Cope, Proc. 

 Phila. Acad., 1866, p. 310. — Crotalus MitchelUi Cope, in Wheeler's Surv. 

 West 100 Mer., V, p. 535, (1875).— Cope, Bull. U. S. Nat. Mus., No. 1, 

 Check-list, p. 33 (1875).— Cope, Bull. U. S. Nat. Mus., No. 32, p. 90 (1887).— 

 Cope, Proc. U. S. Nat. Mus., xiv, 1891 (No. 882), p. 694 (1892).— Den- 

 burgh, Proc. Cal. Acad. Sc. (2) iv, 1894, p. 450. 



l^m.— Crotalus Mitchelll, Yarrow, Bull. U. S. Nat. Mus., No. 24, Check-list, pp. 12, 

 73, 189. 



1883. — Crotalus oregonus,VAX. Mitchelln, Garman, Kept. Batr. N. Am., i, Ophid., 

 p. 173. 



1891. — Crotalus pj/rrhus, Stejneger, W. Amer. Sclent., vii, April, 1891 (publ. 

 June), p. 165 (in jjart). 



FUjures.- — None. 



Description. \ — Head depressed (figs. 09, 70), covered with small, 

 irregular scales, j)osteriorly keeled ; anteriorly, and upon the obtuse 

 muzzle, rugged, free at the lateral or hinder edges. Superciliaries 

 (supraoculars) prouiinent, Striate rugose. One loreal; nostril large, 

 prenasal small, higher than long, separated from the rostral and supe- 

 rior labials by small scales. Rostral low, an equilateral triangle. 

 Sixteen superior labials, the last large, 3 rows between them and the 

 orbit; temporals large, smooth. Superior labials, 16. Scales elon- 

 gate, striate rugose, iu 25 rows, all strongly keeled except the first. 

 (Jrepitaculuin (rattle) well developed, of the ^. atroxty\)e, i. e., strongly 

 compressed, having the terminal complete segments as broad as the 

 basal. Gastrosteges (ventrals),198; urosteges (subcaudals), 20. Total 

 length (excl. crepitaculum), 44 inches; tail, 3 inches 6 1. (Figs. 69, 70.) 



The color above and below is grayish yellow. The upper surface of 

 the head is shaded, that of the body coarsely and densely punctulated 

 with brown. The regular aggregation and deepness of these punctu- 

 latious form a series of about 42 dorsal spots. These are transverse, 

 with produced lateral angles, extending across 12 rows of scales from 

 angle to angle, separated from the adjacent ones by a bright baud of 



* Named in honor of Dr. S. Weir Mitchell, of Philadelphia. 



t Original description, by E. D. Cope, in Pro^. Phila. Acad., 1861, p. 293, from a 

 Cape St. Lucas specimen in Smithsonian Institution. 



