TEIID LIZARDS OF THE GENUS CNEMIDOPHOEUS 



145 



rather sharply delineated belt from the Panhandle of Texas, south- 

 ward to Coahnila and west to the Gulf of California, pevplexus^ 

 like sexlincatus^ is thought to have been derived directly from gidaris. 

 In view of the distributional facts, it would appear that any inter- 

 gradation which takes place between ferplexus and sexlineatus is 



Figure 25.- — Map s)i()\viNt; distribution of the forms of thk sexlineatus oROur 



purely secondary. This theory is supported by structural and colora- 

 tional data discussed under the affinities of these forms (pp. OG, 

 139-140). 



The recent finding of lahiaUs at San Quentin on the mainland of 

 Lower California, far to the north of Cerros Island, the type locality, 

 excludes the possibility, apparently, of its recent speciation through 

 the agency of insular isolation. The frequent forking of the dorsal 



