5. SAUROMALUS 97 



Distribution. Specimens are at hand from Espiritu 

 Santo, San Francisco, San Diego, Santa Cruz and San Mar- 

 cos islands, in the Gulf of California, Mexico. Miss 

 Dickerson states the type locality as La Paz, Lower 

 California. 



Remarks. This species resembles S. ater in size and 

 general appearance, but its scale counts are quite different. 

 The coloring of the gular region in the specimens from 

 Espiritu Santo seems to differ from that shown by those 

 from the more northern islands, being clearly spotted 

 rather than obscurely marbled, but our series are too small 

 to enable one to judge whether this difference is constant. 

 The specimen from San Marcos Island agrees with this 

 species, rather than with S. ater y in its scale counts, although 

 one from Agua Verde Bay has the counts of S. ater y and is 

 referred to that species. 



13. Sauromalus slevini, new species 

 SLEVIN'S CHUCKWALLA 



Description. Head and body large, much depressed, 

 the latter very broad. Head almost triangular, with nar- 

 row rounded snout, and covered with small plates largest 

 on frontal and temporal regions. Nostrils opening up- 

 ward, outward, and slightly backward, in round plates a 

 little nearer to end of snout than to orbits. Superciliaries 

 like supraoculars, small and juxtaposed. Suboculars all 

 short, but slightly keeled. Rostral plate very small. La- 

 bial plates small and of about equal size. Symphyseal 

 plate long but very narrow. Several series of slightly en- 

 larged sublabials, passing gradually into the finely granu- 

 lar gulars. Gular fold covered with very small scales. 

 Ear-opening large, almost vertical, with strong 'anterior 

 denticulation of spinose scales. A strong fold on each side 



