96 [June, 



ciliary plates developed, so as to present two horn-like processes, one on each 

 side of the head at their middle; nostrils small; pits between the eyes and nos- 

 trils large ; twenty rows of carinated scales, the inferior rows near the abdomen 

 smooth; body slender, much compressed; tail very short, with three or four 

 rattles. 



Coloration. Head ash color above, a black band running from the posterior 

 margin of the orbit to within a line of the occiput ; a series of forty-one transverse 

 brownish bands, yellow in the centre, along the back; general color of animal 

 above light yellow; several transverse bands upon the tail ; under surface light 

 yellow, slightly clouded with spots near the external margin of the abdomen; 

 abdom. scut. 146 ; two rows of bifid post-abdom. scutell. ; 14 single caudal scuta ; 

 three inferior rows bifid. 



Dimensions. Length of head 5 lines; greatest breadth 4 lines; length of body 

 8 and 3-8th inches; of tail, | ; total length 9| inches. 



Hab Borders of the Mohave river, and in the desert of the Mohave, always 

 in the dry sandy soil, with no vegetation whatever. Maximum size one foot 

 and a half; occurs in large numbers, and is also seen in the Desert of the Colo- 

 rado, but is much less abundant, Dr. Heermann not having observed it ihere. 

 The river Mohave spreads itself out in the desert and there loses itself, and upon 

 the floating sand hills near it these animals are found. The Crolalus Lecontii 

 is never seen with them. The Mohave empties into a salt lake about 15 miles 

 in extent. 



Gen. Remarks. I supposed that this animal might be the young of Crotalus 

 Lecontii, but Dr. Heermann informs me that the Lecontii is never found with 

 it, and that it never attains to more than a foot and a half in length, and always 

 presents the horn-like processes above described. It would appear to be the 

 representative of the Vipera Cerastes of Africa, and is found, like that serpent, 

 in desert and sandy regions, and is also slow and sluggish in its movements. 

 The genus Cerastes, proposed by Wagler and adopted by Dumeril and Bibron, it 

 would appear should be dropped and Vipera substituted. 



BATRACHIANS. 



Rana nigricans, nob. 



Sp, char. Remarkable for its size ; color uniform, dark brown, with numerous 

 small black spots, and large blotches interspersed over the surface ; sides some- 

 what lighter, marked with black; anterior extremities dark brown, or ash color 

 above, blotched with black ; posterior of same color, with numerous transverse 

 black bands; chin, throat and abdomen straw color, shaded with brown; under 

 surface of extremities yellowish, marked with black. 



Dimensions. Length of head, neck and body, 4 inches; greatest breadth of 

 head, If inches; length of anterior extremities, 1| inches: of foot anteriorly to 

 extremity of longest toe, 1 inch; of posterior extremity, 5 inches; length of hind 

 foot, If inches ; of foot posteriorly to distal end of longest toe, 2| inches. 



Hab. El Paso Creek. 



Gen. Observations. This species is remarkable for the great length of its 

 posterior extremities; allied to Rana Draytoni, Baird and Girard, but the 

 posterior extremities appear to be longer. 



Hyla nebulosa, nob. 



Sp. char. Uniform light grey upon the upper part of the body and sides ; 

 snout light ash ; a considerable number of dark colored subcircular spots about 

 a line in diameter, scattered over the upper part of the body and upon the sides ; 

 extremities ash color above, with greyish spots; abdomen greenish yellow; chin 

 light yellow; under surface of extremities orange colored; abdomen and under 

 surface of extremities granulated. 



Dimensions. Length of head, neck and body, If inches; greatest breadth of 

 head, | inch; length of anterior extremities, If inches; of posterior extremities 

 2 and 3-8th inches to extremity of longest toe. 



Hab. Tejon Pass. 



