48. CROTALUS 929 
and eye. Scales in 25 to 29 rows, keeled except in one to 
three rows of each side. Gastrosteges varying from 177 to 
188. Urosteges 16 to 28. 
The ground color is grayish or yellowish brown, marked 
along the back with a series of large darker brown blotches 
which usually become cross-bars or incomplete rings post- 
eriorly. These blotches are paler centrally than about their 
edges, and vary greatly in shape and amount of separation. 
Smaller alternating dark blotches are usually present on the 
sides. Many of the scales between or around the dark dorsal 
blotches are light, either gray or white. These colors some- 
times show between the dark lateral blotches also. Many 
specimens show a light transverse streak on the supraocular. 
A dark streak runs from the eye to the corner of the mouth, 
the line of its lower edge passing in front of the eye or 
striking it about under its anterior corner. This dark streak 
is bordered above by a light streak which is not wider than 
the width of one scale and passes above the corner of the 
mouth. Another narrow light streak crosses the side of the 
face below the dark one, and is bordered in front by dark 
brown on the side of the snout. The tail is provided with 
brown and light rings or cross-bars, a few of the former, 
near the tip of the tail, being sometimes blackish. The lower 
surfaces are dull yellow or white, sometimes clouded with 
brown. 
“The color varies greatly, being sometimes duller, some- 
times brighter, lighter or darker, depending upon age, sea- 
son, condition of skin, climate, and the predominating color 
of surroundings.”* 
er the toma mf) See eee ee 595 
ien'ethvot tallito\nattle= = ee a / 
Distribution —“Broadly speaking, the Prairie Rattle- 
*Stejneger, Report U. S. Nat. Mus. for 1893. 
