POISONOUS SNAKES OF NORTH AMERICA. 453 



The color above is greenish gray, which is crossed by 19 jet-black 

 rings on the body (fig. 54), which do not extend on the abdomen. 

 These rings are 2i scales wide on the middle line, and narrow down- 

 wards on each side so as to cover bnt 1 scale in width. The scales 

 which border the annuli are half black and half green, the effect of which 

 is to give the edge of the ring a turreted outline. The edges of the 

 ground-color are paler than any other part of the scales, tlius throw- 

 ing the black into greater relief. 

 A large black vspot, shaped like !i 

 heai'ts side by side with the apices 

 posterior, marks the nape, and there 

 is an irregular small black spot on 

 each side of the occiput. Some black 

 specks between the orbits. No other -p^^ 



marks on the head. Near the middle head of crotalus lepidus, side view. 



<> J.1 ^ j-l 1 1 Cat. No. 21057, U. S. N. M 



ot the gray spaces of the body some 



of the scales of many of tlie rows have black tips. The tail is light 

 brown above and has a basal broad black, and 2 other narrow brown 

 anniili. Below, dirty white with closely placed shades of brown. 



Variation. — Prof. Snow, in 1884, in a letter to the reptile deiiartment 

 of the National Museum, describes the fresh color of the specimen just 

 described, taken by him at the head of Water Canyon, .New Mexico, in 

 August of 1881, from memory, as being of " an unmistakable glaucous 

 or grayish green" which contrasted beautifully with the jet-black bands. 

 In the specimens in the National Museum the bands are brown in the 

 center, black at the edges. 



In the scutellation of the head there is some variation, but nothing 

 out of the unusual. The nostrils are comparatively small, and Kenni- 

 cott originally described the species as having them situated in an undi- 

 vided nasal, which afterwards led Cope to institute the genus Aploaspis. 

 The two heads upon which the species was originally based do not seem 

 to be in existence any more, but in the specimens which I have examined 

 there is certainly a division of the nasal at least below the nostril. 

 The upper i)reocular appears always to be divided vertically. 



In 3 specimens examined by me the scale rows varied from 21 to 23; 

 the ventrals (gastrosteges), from ICO to 163; subcaudals (urosteges), 

 from 24 to 25. 



Geographical distribution. — This species, although apparently ex- 

 tremely rare, seems to occur all along our Mexican border, at least 

 from Eagle Pass on the Rio Grande to Yuma on the Colorado. Since the 

 two heads collected by the Mexican Boundary Survey parties at Eagle 

 Pass and Presidio del Norte, no specimens have been recorded from 

 Texas. Prof. Frank Snow, however, in August, 1881, obtained a specimen 

 at the head of Water Canyon, just west of Socorro, N. Mex. Shortly 



* Description l)y E. D. Cope, in Proc. Phila. Acad., 1883, p. 13, from a New Mexi- 

 can spcciUK'u collected by Prof. Frank Snow. 



