370 DR. H. GADOW ON EVOLUTION [Miir. 20, 



white and bLack cross-bars on the flanks. The stripes pi-evail on 

 the neck, shoulder, and mid-back, while spots become predominant 

 on the rump. To such specimens applies the name of C. gracilis 



B. k G.* 



The next question is lohether the white colour becomes prevalent 

 and represents the gi-ound-colour, with black spots and lines ; and 

 this condition leads to an extreme in wdiich the wdiite ground- 

 colour turns to dull or brownish, interspersed with black spots 

 onlv, which ultimately may be counted in transveise or in longi- 

 tudinal rows (C. ruhichis, text-fig. 70 E, see p. 293). Or, the black 

 becomes prevalent ; and this condition leads to various appeai-ances, 

 namely, dark -coloured white-spotted (leopards), or with a trans- 

 verse black and white giidiron pattern on the I'ump, or black and 

 white cross-baiTcd on rump and Hanks (tigers). 



Such leopards, gridirons, or tigers, as the case may be (e. g. 



C. tigris of Baird & Gir., and also of Cope, Proc. Am. Phil. Soc. 

 1886, p. 283), occur in the tSonoi'an zone on the open desert, some- 

 times together with the Leopard-lizard Crotcqihytus wisliceni, as 

 pointed out by Mei-riam, quoted by Cope, p. 578. They are also 

 common in the Mojave desert; in Utah, and in Nevada on 

 Juniper Mountain up to 6500 ft. 



These spotted and barred individuals represent one kind of 

 desert form ; another kind is C. ruhidus, in which the whole 

 dorsal surface has become uniform light bi'own, interspersed with 

 black spots. These spots again may become evanescent from 

 neck and shoulders backwards ; such specimens are recorded 

 from 8. Margarita Island, Lower California. 



It would he interesting to ascertain to what extent the more 

 striped individuals coincide in their habitat with those districts 

 which are decidedly not deserts, e. g., the neighbourhood of Laredo 

 from El Paso to S. Antonio in New Mexico, Fresno, Bernalillo 

 and Los Angeles in California. 



Cnemidophorus multiscutatus Cope, based upon four specimens 

 from Cedros Island, West Coast of Lower California, can scarcely 

 claim distinctive rank. 



Cope gives the following data : — Length 85 mm. Humerus 

 with 7-8 rows, but he adds that this number is not quite constant, 

 one specimen having but 6 lows. Femoral rows 8-9, but I fail 

 to count even 8 in Cope's figure. Pores 20-22. Throat and 

 collar with ti-ansverse black spots and bands ; tail with black 

 spots below ; " belly black and light olive mixed." Doi'sal 

 coloration like that of the C gracilis stage of C. tessellatus. He 

 adds that he caught a specimen structui-ally exactly like this 

 multiscutatus near Pyramid Lake in Western Nevada. This, 

 coupled with the fact that Cope himself records four specimens of 



* To none of these stages applies C. ffuttatits Hallowell, as Cope would have it. 

 Hallowell distinctly states that the subgular fold is mai-gined with a row of large 

 smooth scales. 



