18 BULLETIN 15 4, UNITED STATES NATIONAL MUSEUM 



The teeth ju'c iininerous, conical anteriorly, and l)i- or tri-cuspid 

 laterally and posteriorly. The lateral and [)ostei-ior teeth are longi- 

 tudinally compressed. There are no teeth in tlie roof of the mouth 

 (vomerine, palatine, etc.). 



The skull is -weak. I'ather frail, and witli the usual single, npper 

 temporal arch of the lizards. The frontal bones are coositied, 

 etched, and differentiated from the prefrontals. The parietals are 

 fused to each other and the postfrontalis fused with the postorbital. 



As remarked by Cope (1900, p. 557) the nrinary bladder is absent 

 from Cnemido'pliorus^ there being no trace of it in the species 

 examined during the course of the present study. The kidney is 

 unusually thick and is roughly triangular in outline, being widened 

 transversely at its anterior part. The ureters are short, connecting 

 directly with the cloaca. 



The alimentary canal presents the usual parts. The mouth is small 

 and not really capacious. There is an elongate esophagus leading to 

 the stomach, which in turn leads to the convoluted small intestine, 

 rectum and cloaca. A caecum is not present. 



Variation.- — There is a decided lack of variational studies upon 

 North American lizards, with particularily reference to the abundant, 

 wide-ranging forms. Therefore, it is not considered safe to draw 

 general conclusions here. Comprehensive reviews have appeared for 

 certain genera of snakes, particularly those of Ruthven (1908), 

 Blanchard (1921) and Ortenburger (1928). These writers have been 

 able to discuss at length the variation in the ventral, caudal, dorsal, 

 and labial scutellation of their forms, but this type of scalation in 

 C^iemidophonis is seldom significant and therefore there is little 

 need or opportunity to elaborate it here. 



In the several groups of Cnemidophoms, it is found that most of 

 the forms are only color or size variants, and furthermore the greater 

 percentage of the numerous characters exhibited by the many species 

 and subspecies are useless for diagnostic purposes. Among the most 

 reliable taxonomic characters are the following: the position of the 

 nasal opening, the number of parietal plates, the number of fronto- 

 parietals, the number of supraoculars, the type of postantebrachial 

 scutellation, the number of femoral pores and the coloration. Abnor- 

 malities frequently occur in the scutellation, both by splitting and by 

 fusion, and, as already shown, there is much confusing variation in 

 the color and color pattern. 



Range. — Lizards of the genus Cnemidophor-us ma}^ be found from 

 southern Brazil and Bolivia in South America northward to Oregon, 

 Wisconsin, and Maryland in the United States. Insular races are 

 particularly abundant in the Caribbean Sea and in the Gulf of 

 California. 



