164 BULLETIN 15 4, UNITED STATES NATIONAL MUSEUM 



:ukI so it is not possible to use tlieiii to s(,>[)iir;iU! closely lelated 

 species or subspecies from each other. Therefore, such points as 

 " longer foot, longer head, and smaller size," may be passed over 

 with little discussion. As said by Schmidt (102-2, p. 675), "The 

 differences cited in the original description to distinguish estehanensis 

 from melanostethius are inadequate and I am unable to find other 

 characters of greater weight. The coloration seems to be practically 

 identical." The type itself shows the usual four lines of tessellatus, 

 and the pattern is largely longitudinal, since the spots and reticula- 

 tions do not tend to unite transversely as in martyris and canus. 



A series of 17 specimens of tessellatus from San Esteban Island 

 in the collection of the California Academy of Sciences lends weight 

 to the decision that estehanensis is identical with melanosfetJms ( = 

 tessellatus), the form on Tiburon Island and the adjacent Mexican 

 mainland. The ventral color of these varies from, white below in the 

 young to deep black below in the adults. 



A new species, dlckersonae, was diagnosed by Van Denburgh and 

 Slevin (1921, p. 97) from Isla Partida, near Angel de la Guardia 

 Island, (lulf of California. This form was said to be intermediate 

 l)etween stejnegerl and melanostet litis in coloration, possessing the 

 yellowish brown dorsal ground color of stejnegerl and the blaciv gular 

 and thoracic suft'usion of melanostet lius, but the dorsal longitudinal 

 markings were duller than in either stejnegerl or meianostetJms. 

 The sides were dark brown or black and with whitish transverse bars 

 or spots as in estehaneibsls, but the i)aU('i-ii was presumed to l)e 

 different from estehanensis. 



Schmidt (1922, p. G7G) drew attention to the fact that the colora- 

 tion described by Van Denburgh and Slevin for their new species 

 idlckersonae) was exactly the same as that of Dickerson's puncti- 

 llnealis. And Van Denburgh (1922, p. 513) in discussing tessellatus 

 admitted that a specimen from Smith Island was possibly that species 

 {tessellatvs), although the coloration was "not typical" and he 

 regarded it as dicl'ersonae. Disregarding this, the specimen seems 

 to be as near to canus as to tessellatus^ varying from the former only 

 in its somewhat coarser dorsal reticulations. In other words, the 

 Smith Island specimen is intermediate between eaniis and tessellatus, 

 as here defined. 



Just why Van Denburgh and Slevin should have regarded dicher- 

 sonae as intermediate between stejnegerl, the dark-backed form of 

 the higher levels, and melanostethus, the brownish form of the open 

 deserts, is not apparent. It really seems to be nearer the extreme de- 

 velopment of the mehniostetlms phase than to anything else, since the 

 under parts are black in adults, and since the dorsal pattern is light 

 brownish and presents few sharp contrasts. A yellowish brown 



