128 [August, 



Genus Cnemidophorus. 



A. With eight rows of abdominal scales. 



Cnemidophorus marmoratus, B. and G. This species is so closely allied to 

 Cn. tigris figured in Stansbury's Report on the great Salt Lake, that, at first 

 sight, it is difficult to perceive the differences. These consist in the proportional 

 size of the scales, which are smaller on the back and larger on the tail and belly, 

 in Cn. marmorams than in Cn. tigris. The head is broader on the vertex in Cn, 

 marmoratus than in Cn. tigris. Differences in the shape of the cephalic plates 

 are likew^ise obvious when the two species are compared. The hind legs are 

 more developed in Cn. marmoratus than in Cn. tigris, the scales which cover 

 their under surface are larger and extend over a greater area. The ground color 

 is yellowish green, marbled with black, except on the head and posterior part of 

 the tail. 



Locality. Between San Antonio (Texas) and El Paso del Norte. 



Cnemidophorus Grahamii, B. and G. This is a large and beautiful species, 

 strongly suggestive of Cn. tigris, from vihich. it differs by a much smaller and 

 narrower head, and by some differences in the proportional size of the cephalic 

 plates. The scales on the upper region of the body are still more minute than in 

 Cn. marmoratus. Those on the margin of the subgular fold are much larger than 

 in either Cn. tigris and Cn. marm,oratiis. The head is olivaceous ; the ground 

 color of the body reddish-green, with seven or eight longitudinal series of sub- 

 quadrangular black dots, constituting sometimes continuous bands. This species 

 is dedicated to the accomplished officer to whom the U. S. and Mexican boundary 

 survey was, for a short time, entrusted. His name has long been associated 

 with the progress of science in the United States, from the date of the first ex- 

 pedition of Major Long, to the present time, and we take great pleasure in ten- 

 dering this especial mark of respect. 



Locality. Found with the preceding species. 



CNEMmoPHORUS GULARis, B. and G. Allied to Cn. sexlineatuSf of which it 

 has the general appearance. The body, however, is shorter, the fore and hind 

 legs are more developed, and the scales on the upper region of the body smaller 

 than in the latter species. Another very striking difference is to be found on the 

 subgular fold, where the marginal scales are considerably larger than in Cn. 

 sexlineatus. 



Localities. From Indianola, (Texas,) and the valley of the Rio San Pedro, a 

 tributary of the Rio Grande del Norte. 



Cnemidophorus perplexus, B. and G. This species has the general appear- 

 ance of C71. Grahamii, having like the latter a proportionally small and narrow 

 head, which distinguishes at once these from both Cn. tigris and Cn. marmoratus. 

 From Cn. Grahamii it differs by the absence of large scales on the margin of the 

 subgular fold. The scales on the upper part of the body are nearly the same, 

 but those on the belly are larger in Cn. 'perplexus than in Cn. Grahaviii. The 

 ground color is yellowish green, with seven yellowish stripes extending from the 

 occiput to the origin of the tail. 



Localities. Valley of the Rio San Pedro of the Rio Grande del Norte. Speci- 

 mens were also collected by Gen. Churchill, on the Rio Grande west of San 

 Antonio, (Texas,) and by Dr. William Gambel on his last journey to California. 



Cnemidophorus gracilis, B. and G. This species comes nearer to Cn. per- 

 plexus than 10 any other of the same genus, but the head is still narrower, the 

 body, tail, and legs slender, and proportionally more elongated. The scales on 

 the lower surface of the head and throat are much smaller than in Cn. perplexus. 

 The color is bluish black above, with four yellowish white narrow stripes extend- 

 ing from the occiput to the origin of the tail. 



Locality. Desert of Colorado; collected by Dr. John L. Le Conte. 



