NINTH ANNUAL REPORT. 199 



time its striking blue-gray color has attracted considerable in- 

 terest. The snake presents the appearance of being coated with 

 pumice dust. 



CROTALUS PULVIS. SP. NOV. 



GRAY RATTLESNAKE. 



Locality. — This specimen was captured twenty miles inland 

 from Managua, Nicaragua, /;/ a very dry, sandy district. 



Relationship. — The species is most nearly related to Crotalus 

 durissiis {terrificus) of Mexico, Central and South America, from 

 which it differs in the following characters : 



1. The much smoother character of the scales of the head; 



2. The less tubercular striation of the scales of the dorsal 

 region ; 



3. The entirely different ground color, and almost total absence 

 of color pattern ; 



4. Its small size at maturity. The specimen described is adult, 

 yet it measures but a trifle over two feet in length, while C. duris- 

 siis attains a length of six feet. 



Seal at ion. — On the upper surface of the snout are three pairs of 

 plates, the central pair much the larger, and extending to about 

 one-third the length of the supraoculars. There are three rows 

 of flat scales between the central portion of the supraoculars. 

 The central portion of the top of the head is covered with small, 

 almost smooth scales. The scales of the temporal region are 

 stronglv keeled, although the carinae are not so sharply raised as 

 with C. durissiis. There are thirteen superior labials. Four rows 

 of scales separate the eye from the labial plates. 



The dorsal scales are in twenty-seven rows. All but the first 

 and second rows are strongly carinated, those of the median 

 region possessing tubercular carinae, though this character is 

 considerablv less ] ronounced than with the related species. A 

 count of the abdominal i)lates and urosteges shows 167 of the 

 former and 23 of the latter. The anal is entire. 



Coloration. — The color is uniform ])ale, l)luish-gray above, 

 matching the tint of pumice-stf;ne. There is ])ractically no color 

 pattern. Immediately after the epidermis has been shed, a chain 

 of verv obscure rhombs, of a slightly darker tint than the body 

 color, may be discerned if the skin is distended. There are no 

 traces of head-markings. The upper surface of the tail is of the 

 same general color as the body. The abdomen and first row of 

 scales are pinkish-white, which tint is deeper on the outer edges 

 of the gastrosteges. 



