1922] Schmidt, Amphibians and Reptiles of Lower California 665 



Sator grandsevus Dickerson 



Saior grandsevus Dickerson, 1919, p. 469. J 



Range. — Ceralvo Island, Gulf of California. 



This species and the following are certainly closely related to 

 Sceloporus through S. utiformis of the Coliman region in Mexico and are 

 much more closely allied to Sceloporus than to Uta. The development of 

 the gular fold and the rudiment of a collar illustrate excellently an inter- 

 mediate stage between Sceloporus with differentiated dorsal and lateral 

 scales and a Uta of the Uta nigricauda type; but it is not at all necessary 

 to assume that Sator is the direct representative of the ancestral Utas, 

 which I believe to have been very different from Sceloporus. The gular 

 fold being more strongly developed than in Uta, and the collar less de- 

 veloped, it may well be that both are parallel structures and that the 

 species of Sator have arisen independently from a Sceloporus stock related 

 to S. utiformis. The three genera Sceloporus, Sator, and Uta form a 

 group of North American iguanid genera much like that formed by 

 Callisaurus, Uma and Holbrookia. 



The distribution of the two insular species of Sator, on widely sep- 

 arated islands off the Gulf coast of the peninsula, suggests that the 

 genus must formerly have inhabited the mainland of the peninsula, 

 where it is now almost certainly extinct. 



Sator angustus Dickerson 



Sator angustus Dickerson, 1919, p. 469. 2 



Range. — Santa Cruz Island, Gulf of California. 



The measurements of the type of this species are, unfortunately, 

 placed after those of Sator grandsevus in the original description. The 

 anterior gular folds in this species is much more definitely marked by 

 differentiation of the scales than it is in grandsevus. In the latter, the 

 fold is marked by an abrupt transition in size of the gular scales, which 

 are about twice as wide behind the fold as the scales in the series anterior 

 to it. In angustus, a double row of granular scales, much smaller than 

 those on the fold, crosses the throat immediately behind the fold, which 

 thus becomes very similar to the collar of other genera, but is not a 

 homologous structure. In Sator grandsevus, there is a distinct lateral 

 invasion of granules in the position of the posterior gular fold, i.e., an 

 incipient collar homologous with the collar of Uta. In angustus, there 



■Type: U. S. N. M. No. 64261. 



2 Type: U. S. N. M. No. 64262. Paratypes: U. S. N. M. Nos. 64474-78; A. M. N. H. Nos. 5713- 

 16, 5719, 5722. 



