166 BULLETIN 15 4, UNITED STATES NATIONAL MUSEUM 



develop tiger bars, Cope (1892c, p. 42) considered the form as a 

 " distinct species which resembles the partly cross-banded examples 

 of tesseJlatus in coloration." These partly cross-banded forms of 

 tessellatus have been noted to be particularly common in certain 

 collections from Utah. 



Perhaps the strongest argument for uniting gi'alunnil of Texas 

 and stejnegei^l of the west coast with the intervening form in the 

 Great Basin is the demonstration of their similarities. It has already 

 been emphasized that they occupy similar habitatas which corre- 

 spond with the higher levels -^ tolerated by these lizards and that a 

 single structural modification, a tendency toward the enlargement of 

 the mesoptychial scales, is found in both. It lias also been shown 

 that they develop a dark dorsal coloration and that tiic \'enti'al parts 

 tend to Ikhc a white ground coloi' which is dcxoid of smoky 

 suffusion. 



It is little woiidei' that Cope (1900) was lead to refer to xf<jtu (jcrl 

 as a subsc])ecies of </i<ih(iitii}, or that various workers I'eported (jm- 

 /kuhH from the west coast before and even after sfejiieyer/ was 

 (lesci'il)ed. among them l)oc()urt ( 1<ST4. }). 2Ts). Moccpiard (1S99) and 

 Ditmars (1907, p. IST). 



In 1854 undulatvs was described from California by Hallowell. 

 An examination of the type shows that ii had a few black spots 

 on the gular i-egion and that the dv^rsal fields are dark, tending to 

 be rather confluent longitudinally, although often broken through by 

 white crossbars. As in specimens of fessellafus from the Great 

 Basin, the tessellation is more pronounced on the sides than on the 

 back where the dorsal interspaces often have spots which have not 

 spread to form crossbars or lines. 



The followdng statements taken from Stejneger (1893, p. 200) 

 give an excellent analysis of the variation exhibited by these lizards 

 in the region of Death Valley: ''Ten specimens from the west slope 

 of the Sierra Nevada differ so nnich from the desert specimens that 

 I must regard them as entitled to a separate trinomial appelation. 

 So far as I can see there is no structural difl'erence. nor is there a 

 very radical difference in the color of the pattern. The latter 

 is considerably coarser, better defined and deeper in color. The 

 difference between the two forms in this respect is ])articularly well 

 marked on the sides of the head, the darker marks being nearly 

 obsolete in the desert form, Avhile in the latter the slate colored 

 suffusion on the under side seems to the I'ule. T have yet to see a 

 specimen from the great iiilei-ioi' Nalley of Califoi-iiia in which it is 

 present. 



=1 In this connection it is intoresting to note tliat Bailey (1913) assigned (jnihaniii to tlie 

 upper Sonoran Zone of New ^lexico, wlicreas lie assigned both mclaitofitrlliiix and lif/ris 

 to the Lower Sonoi'an Zone. 



