352 REPORT OF NATIONAL MUSEUM, 1898. 



central region for a width of some six scales, where the scales are more 

 continuously colored than in Cat. No. 29o2. Some of these scales have 

 a tinge of green. The black cervical collar above is margined before 

 and behind by a lighter shade of the ground color; as in Cat. No. 2952, 

 there is one dusky band on the nape. The scales on the supraorbital 

 region are more broken up and tubercular; the occipital plate narrower. 

 The blue or green of the sides has no black margin anteriorly or exter- 

 nally. It extends nearly to the axillae. 



In some specimens the chin is spotted with blackish. In many the 

 scales on the chin and sides are yellowish, but when removed the sub- 

 jacent skin is seen to be bluish. 



In Cat. No. 2960 the ground color on the back is greenish, with an occa- 

 sional yellowish scale; the blotches and cervical crescent, as described. 

 The chin is greenish, with a longitudinal line of yellowish; the lateral 

 region spotted with the same. There are obsolete bands of lighter on 

 the back between the dusky portions. 



This species is very similar to S. torquatus Wiegmann in general 

 appearance and character, but differs in several appreciable points. The 

 plates on top of head are much more irregular. Then there is no sym- 

 metrical lateral occipital, although there is a plate larger than the others 

 adjacent to it. The .second series of three plates is entirely broken u]} 

 into irregular small ones; the more anterior ones are jiretty much the 

 same in both. The supraorbital plates are much more irregular and 

 tubercular, the central ones smaller. There is no tangible diflerence in 

 the infraorbital series. The plates on the temporal region, between the 

 eye and ear, and those on the under surface of feet are considerably 

 larger. The fingers and toes are shorter. The scales on the middle of 

 the back are flatter, more membranaceous, more truncate behind, and 

 much less connected — in fact, usually smooth. 



The color differs in being yellowish above instead of green; the dor- 

 sal blotches and the large blue patch on the flank, are more distinct. 

 The black collar is more crescentic or rounder behind than V-shaped, 

 and lacks the distinct process separating the yellowish anterior margin. 

 The light markings anterior to the collar and its margin are in the form 

 of transverse bands, not spots. 



The largest of its genus found in Texas, this species has nearly the 

 range of the S. spinosus. I found it very abundant in the first plateau 

 region as far as the upper waters of the Guadalupe, It differs in its 

 habits from the 8. spinosus, being exclusively a dweller in rocks. It 

 maybe seen at any time running over the limestone clifi's of the plateau 

 region, to which its light colors present but little contrast. The relation 

 between its color and habitat is quite as striking as in the S. spinosus. 



i 



