TEIID LIZARDS OF THE GENUS CNEMIDOPHORUS 217 



The evolution and variation of the color pattern of ceralhcnsis 

 is of particular interest. The under parts of the body are always 

 more or less mottled with black and white. The oround color of 

 the upper chest chaii<i;es from slaty in the youn<;- to black in the 

 adult. The mottled chest is often like that of specimens of tcssella- 

 tus from western Nevada and other points, but never like examples 

 of the latter species from southern Arizona, at which place the black 

 of the upper chest of adults is generally unbroken by white spots. 

 The mesoptj'chium is dark in color, except in very young specimens, 

 and even in the latter a lateral patch of slate is present on each 

 side. The ventral caudal scales often have black centers as do 

 those of C. tessellatus tesseJlatus. 



On the sides are two broad, distinct stripes. In the youngest 

 specimens the lower stripe sends out a series of from 14 to 23 narrow 

 white projections into the interspace above and into the black 

 ground below. The pattern remains so, and the projections grow 

 scarcely more or less prominent with the ontogenteic development 

 of the individual, so complete tessellation is never effected. The 

 lower stripe never fades. Often the upper lateral stripe on each 

 side produces bars similar to those of its adjacent lower lateral 

 stripe and in such cases individual bars from the upper lateral 

 stripe, and like bars from the corresponding lower lateral, may unite 

 in the connecting interspace to form a single white bar or passegeway. 

 Bars from the upper lateral stripe usually do not project into the 

 dorsal area, and when they do they are decidedly weaker than the 

 lower ones. Bars are never developed betAveen the two dorsal 

 stripes, but a third stripe often appears there as in ln/perythrus. 

 This middorsal stripe is often so indistinct that an opinion as to 

 its presence or absence becomes largely a matter of speculation. In 

 other cases the dorsal stripes on each side may approach so closely to 

 the center stripe, and the center stripe may be so diffuse, that all 

 three unite in forming a single dull, yet conspicuous, wide middorsal 

 band of whitish or j^ellowish hue. Also, in a few instances at least, 

 a broad, light band is formed by the approach and diffusion of 

 the two dorsal stripes when the median stripe is absent, and in other 

 more numerous cases the Iavo dorsals are widely separated and with 

 a distinct blackish band between them. A complete union of the 

 dorsal stripes has not been observed in any of the 103 specimens 

 examined, and evidently a forked dorsal stripe (similar to that of 

 certain specimens of hypcn/tlirus) does not appear. 



The hind legs of the young specimens are covered with large white 

 spots which become yelloAvish in adults. The ground color of the 

 femora is always similar to that of the lateral interspaces. 

 230G— 31 15 



