926 16. CROTALIDAE 
The general color is yellowish brown, or brownish yel- 
low, with a series of large darker brown blotches along the 
back. These blotches are well defined, are usually enclosed 
in continuous light borders laterally as well as dorsally, and 
show little of the punctulate or pepper-and-salt style of 
coloration so characteristic of C. atrox. The sides are clouded 
or blotched with brown more or less indefinitely outlined 
with light yellow or white. The head is somewhat mottled 
above. A yellow or white stripe runs across the side of the 
face from the preocular plates to the mouth. The scales 
behind and above this light stripe are darker than the ground 
color and are set off posteriorly by a light streak which runs 
down and back from the corner of the eye and strikes the 
supralabials in front of the corner of the mouth. The tail 
is grayish with about four to six black cross-bands. The 
lower surfaces are yellowish white. 
Length) to-anus. —-900 925 935 1062 1070 
Length of tail to base of rattle__ 47 53 80 78 90 
Distribution —Crotalus lucasensis may be restricted to 
the Cape Region of Lower California, where it has been 
taken at Cape San Lucas, La Paz, Pidulingua [ Pichilinque? ] 
Bay, San Jose del Cabo, Sierra E] Taste, and Agua Caliente. 
Five rattlesnakes from San Jose Island seem to belong 
to this species. 
213. Crotalus confluentus Say 
PRAIRIE RATTLESNAKE 
Plates 101 and 110 
? Crotalus viridis Rarinesque, Am. Month. Mag., Vol. IV, 1818, p. 
41. 
Crotalus confluentus Say, In Long’s Exped. Rocky Mts., Vol. II, 1823, 
p- 48 (type locality, “Valley of the Arkansa,” near Bell’s 
Springs, Colorado); Barrp & Girarp, Cat. N. Amer. Rept., Pt. 1, 
Serpents, 1853, p. 8; Barrp & Grrarp, in Marcy’s Expl. Red River, 
