X 28 Bulletin of Laboratories of Derdsen University [Voi. xi. 
median line ; flanks blue, passing into black; black spot in front 
of shoulder. 
Measurements: Length of anus, 57-55 mm.; Snout to 
ear, 15-13 mm.; Width of head, 12— ii mm.; Fore leg, 28-27 
mm.; Hind leg, 34-32 mm.; Base of fifth to tip of fourth toe, 
15-14 mm. 
With the materials at hand it is impossible to discriminate 
S. occidentalis from S. biseriatus. The basis of separation of- 
fered by Van Denburgh in the coloration of throat, which in 
males of S. occidentalis said to have two dark lateral spots, 
while in S. biseriatus they may be confluent. He says “I have 
examined many hundreds of specimens of S. occidentalis and 
biseriatus and have not found a single male of the latter with 
two blue throat patches. Highly colored male of S. occiden- 
talis are sometimes found in which the two blue patches have 
extended to end even merged on the median line, but by secur- 
ing very young or less brilliantly colored males, there should be 
no difficulty in determining which species occurs in a given lo- 
cality. ” Unfortunately he omits to say how he knew that he 
was dealing with a given species while determining the validity 
of the sole criterion. S. occidentalis is said to be the more 
northern species. It may be that the best plan is to accept 
Boulenger’s suggestion and call all the phases of this exceed- 
ingly variable group varieties of S. undulatus. This form, what- 
ever it is, is extremely abundant in the Rio Grande valley and 
the range of individual variation is enormous. 
Sceloporiis Consohrinus, Baird and Girard. 
Description : Head and body little depressed, fusiform ; 
nasal opening nearer the end of the snout than the orbit; upper 
head plates smooth, somewhat convex, not obviously imbri- 
cated ; interparietal largest ; frontal divided transversely, ceph- 
alic portion much larger than the caudal ; parietals and fronto- 
parietals separated by small granules from the enlarged supra- 
oculars ; latter broad (but not so broad as in S. magister) and 
separated by a number of scales from the narrow, imbricated 
superciliaries; sub-occular keeled; rostral plate wider than high; 
