SERPENTS. 



399 



by Laving tlie nasal plates divided ; four prefrontals ; eighteen labials ; seventeen 

 infralabials, and the scales in twenty-four rows. The body is yellowisli, strongly marked 

 with a dorsal series of rhombs, similar to tliose of C. ada/nanteus. An allied species 

 collected at Fort Wiiipi)le, measuring tliirty-one inches in length, contained an adult 

 blue-bird, Sialia mexicaiia. They ai'e reported from the San Francisco mountains 

 at an elevation of 10,000 feet, and inhabit dry rocky ground. C. confiuentus, the 

 ]»raii-ie rattle-snake, is very abundant along the Missoui-i Kiver and its tributaries from 

 Nebraska to the IJocky Mountains. During tlie hot season they retire to tlie dry 

 canons, where they hide among the willows, being extremely sluggish and stupid, and 

 possibly partially blind, as the cuticle, though cleaving from the body and eyes, is not 

 as yet shed. Tlie liead is sub-triangular, and the plates irregular, angulated, imbri- 



Fig. 230. — Civtahis (tunssus, ratlle-suake, 



- ==:5^^fp^^ 



cated, and not infrequently tuberoulated. The labials are from fourteen to eighteen 

 above and below, and the scales of the body :n-e arranged in from twenty-five to 

 twenty-nine rows. Along the back there are between foi'ty and fifty brown spots 

 margined with narrow white lines. C. poh/stktns, inhabiting the table-lands of 

 Mexico, seldom reaches the lengtli of two feet. There are two nasals, two loreals, 

 fourteen laljials, and thirteen infralabials; and, of the twenty-seven rows of scales, all 

 are keeled excepting tlie lower two. Along the back is a median yellowish stripe bor- 

 dered by lines of grayisli lirown, and ornamented by a series of seven brownish black 

 spots. 



C. lucifer, the western black rattle-snake, was brought to the light of science in 

 1852, by the description of Baird and Girard from specimens captured by members 

 of the exploring party under Cajitain Chas. Wilkes in California and Oregon. The 



