1906.] IN MEXICAN LIZARDS. 369 



Two specimens in the Brit. Mus. from Bernalillo Co., ISTew 

 Mexico, 67 and 72 mm. in length, possess 7 complete white stripes, 

 the central being zigzag, but there are white spots in the first 

 and second fields. Under parts all creamy white ; throat without 

 spots. Structurally they agree with C. pei-plexv^s. Humerus 

 with 4 rows of large scales, femur with 6 or 7 rows ; anterior 

 side of forearm and tibia with 3 rows ; pores 18 and 19. 



Specimens from Pecos according to Brown : — Largest 64 mm. ; 

 7 stripes; pores 13-18, averaging 15 only. He remarks that a 

 few of the scales (granules) of the posterior side of the forearm 

 are sometimes a little enlarged, and that two of the sjDecimens 

 have " large scales on the edge of the collar " instead of granules. 

 Brown therefore considers C. perplexus as a subspecies of 

 G. sexlineatus. 



Cnemidophorus tessellatus * Say. (Text-figs. 70 & 64 A.) 



Length of adult 80-100 mm. Humerus with 4 or 5 large rows 

 (Brown, 4 to 7) ; femur mostly with 7, rarely with 6 or 8 rows. 

 Pores, according to Cope, 17-21 ; according to Brown two specimens 

 from Pecos with 24 and 25 ; fifteen specimens from Alamogordo- 

 New Mexico, with 22-25, average 23. 



There is a variable number of stripes which tend to become 

 destroyed by white field-spots. Throat and I'est of under parts 

 with sparse black sjDots. 



Bange. From the Coast of California to ISJ'evada up to 6500 ft., 

 Utah, Arizona, New Mexico, Basin of Rio Grande and Pecos in 

 Texas. Also in Lower California and on Cedros Island. 



The variations of the colour-pattern are enormous and seem to 

 be progressive, bearing several striking analogies to those observed 

 in the gularis and clepjjei groups. The successive changes, mainly 

 as pointed out and figured by Cope, are as follows. It must be 

 borne in mind that the individuals of local clans may stop short 

 at any of these stages, cases of Eimer's " Genepistasis." 



The young start with 6 or more stripes ; the first and second 

 of which bi-eak up into longitudinal spots, and a series of white 

 lateral spots seems likewise frequent. White spots apjDear in the 

 fields, and either join the white stripes, or they gradually break 

 up the fields transversely. This may result in the formation of 



* Cnemidophoeus geahami Baird & Girard. 



Based upon two specimens from between El Paso and San Antonio in New 

 Mexico ; two other specimens reported from Jule Canon on the Staked Plain of 

 Texas. 



According to Cope, C. stejnegeri (which itself is synonj'mous with C. tessellatus) 

 differs from C. graliami in coloration onlj'. If this were the case, the latter would 

 also belong to the tessellatiis-g'^ov.'p, most likelj^ to C. perplexus, with which the 

 pattern of colour agrees very well. Possibly the grahdmi specimens have somewhat 

 enlarged scales forming a central cluster on the mesofitychium, as is not uncommon 

 in C. tessellatus, e. g., from San Diego, and this feature has been exaggerated in 

 fig. 117 of Cope's work. The figures on pi. 37 of the Mexican Boundary Commission 

 are too fanciful to be considered. 



A. E. Brown records one specimen from Pecos, Texas, with 21 pores, "almost 

 identical with C sexlineatics in scale characters." 



