NATURAL SCIENCES OP PHILADELPHIA. 293 



Caudisona enyo Cope. 



Head depressed, covered with small keeled scales. Superciliaries large, 

 prominent, preceded by a small marginal plate ; muzzle covered above with 

 nearly equal polygonal scales, slightly or not keeled. Rostral plate low, in 

 form a nearly equilateral triangle : nasals two, the anterior in contact with the 

 rostral : numerous small scales anterior to the fovea lachrymalis. Thirteen or 

 fourteen superior labials, the posterior small ; fourteen and fifteen inferior, the 

 second, third and fourth in contact with the geneial. Two rows of smooth 

 scales, and the infra orbital circle, separate the labials from the orbit; the 

 scales of the former continue smooth upon the temporal region, and are larger 

 than the labials. Scales of the body rounded, short upon the sides, especially 

 those of the first three rows which, near the middle of the body, are not at all, 

 or scarcely, keeled. Total number of rows 23, the median very strongly 

 keeled, none rugose striate as in atrox. Crepitaculum moderate, its seg- 

 ments diminishing in breadth towards its extremity. Gastrosteges 1<J6. Uro- 

 steges 23 single, 3 pair double. Total length (including crepitaculum) 29 in. 

 9 lin. Tail 4 in. 3 lin. 



General color above, light greyish brown, shaded with yellow ; vertex 

 rufous, marked with a pair of small brown spots. A light baud, bordered 

 with dark crosses each superciliary plate ; from the inner border of the same 

 plate commences a chestnut brown band, which diverges from its fellow on 

 the posterior part of the head, where it is either interrupted or continuous 

 with a broader one which nearly joins that of the opposite side on the neck : 

 here they are either interrupted, or continuing, unite on the neck, and form 

 the first spot. A brown band extends from the eye to the canthus oris, in- 

 volving the last labial plate, and is continued beyond, forming a spot on each 

 side the throat. A series of about thirty-three spots ornaments the middle 

 line of the back ; posteriorly they are of a wood brown color ; the others chest- 

 nut brown bordered with black. Anteriorly the spots are longer than broad, 

 emarginate anteriorly and posteriorly ; opposite to each is a black spot upon 

 scales of the first, second, and third rows. The dorsal spots become broader, 

 resembling transverse rhombs, with light borders outside the black ; the 

 lateral angles become confluent with the lateral black spots, forming vertical 

 black bands on the sides. They finally assume the form of transverse brown 

 bands. The tail is crossed by five of these, upon a brown ground. Beneath 

 yellow ; tips of many of the gastrosteges blackish. Inhabits Lower California, 

 whence specimens have been sent to the Philada. Academy and Smithsonian 

 Institute, by Mr. John Xantus. Type 4663. Xant. Coll. 



This species bears considerable resemblance to C. m o 1 o s s u s in its style 

 of coloration, and like it, is a beautiful animal. The latter species is scutel- 

 lated upon the muzzle, as in C. d u r i s s a : the rows of scales are more nume- 

 rous than in the enyo, and it is without the head stripes. 



Caudisona mitchellii, Cope. 



Head depressed, covered with small irregular scales, posteriorly keeled, 

 anteriorly, and upon the obtuse muzzle, rugged, free at the lateral or hinder 

 edges. Superciliaries prominent, striate rugose. One loreal ; nostril large, 

 prenasal small, higher than long, separated from the rostral and superior 

 labials by small scales. Rostral low, an equilateral triangle. Sixteen supe- 

 rior labials, the last large, three rows between them and the orbit; temporals, 

 large, smooth. Superior labials sixteen. Scales elongate, striate rugose, in 

 25 rows, all strongly keeled except the first. Crepitaculum well developed of 

 the C. a t r o x type, i. e. strongly compressed, having the terminal complete 

 segments as broad as the basal. Gastrosteges 198; urosteges 26. Total 

 length (excl. crepitaculum) 44 in., tail 3 in. 6 1. 



The color above and below is greyish yellow. The upper surface of the 

 head is shaded, that of the body coarsely and densely punctulated with brown. 



1861.] 



