48. CROTALUS 951 



Merid., Appendix NN, 1878, p. 210; Yarrow, Bull. U. S. Nat. 



Mus., No. 24, 1883, pp. 12, 73; TowNSEND, Proc. U. S. Nat. Mus., 



Vol. XIII, 1890, p. 144; Stejneger, West Amer. Scientist, Vol. 



VII, 1891, p. 165; Cope, Proc. U. S. Nat. Mus., Vol. XIV, 1892, p. 



694. 

 Crotalus confluentns var. pyrrhtis Garman, Mem. Mus. Compr. Zool., 



Cambr., Vol. VIII, No. 3, 1883, p. 173. 

 Crotalus oregonus var. mitchelli Garman, Mem. Mus. Compr. Zool., 



Cambr., Vol. VIII, No. 3, 1883, p. 173; Garman, Bull. Essex 



Inst., Vol. XVI, No. I, 1884, p. 35. 

 Crotalus Mitchellii pyrrhus Stejneger, Report U. S. Nat. Mus. for 1893, 



189s, p. 456. 



Description. — Moderately large. Head rather small, 

 with flattened top, varying in outline according to position 

 of fangs, etc. Rostral either higher than wide or wider 

 than high, separated from anterior nasal by one to two rows 

 of granular scales. Usually two nasals, and two preoculars. 

 Postoculars usually three, sometimes four. Supraocular large, 

 somewhat projecting laterally, separated from its fellow by 

 from four to eight scales. Thirteen to 18 superior and 14 

 to 1 8 inferior labials, first pair of latter meeting in front of 

 a single pair of genials. Three to five rows of scales between 

 supralabials and eye. Scales in 23 to 27 rows, keeled except 

 sometimes in one or two rows of each side. Gastrosteges 

 varying from 158 to 198. Urosteges 16 to 27, a few of 

 the posterior sometimes divided. 



The general color is white, gray, yellow, vinaceous-cin- 

 namon, or salmon-red, minutely dotted with black or brown, 

 and with a series of about 32 to 37 indefinite brown, black, 

 or red blotches along the back anterior to tail. These dots 

 and dorsal blotches, as well as smaller blotches which some- 

 times are present on the top of the head and on the sides, 

 may be so faint as to cause the animal to be called the White 

 Rattlesnake, or so dark as to produce a blackish eflFectj the 

 blotches, however, never have definite outlines, appearing 



