38 



BULLETIN 17 5, UNITED STATES NATIONAL MUSEUM 



form, many of the trends in variation observable from affiinis outward 

 along the lines of evolution of the vertebralis, catenifer, and sayi- 



0.160 

 0.155 

 0.150 

 0.145 

 0.140 

 0.135 

 0.130 

 0.125 

 0.120 

 0.115 

 0.110 



25 



deppei 



jani 



lineaticollis 



d«ppei 



l.ncntlcollit 



Figure 20.— Variation in ratio of tail length to total 

 length in the forms of the deppei group. 



FiGCEE 21.— Variation in number of ventrals 

 in the forms of the deppei group. 



melanoleucus groups, would necessarily proceed in a given direction 

 hom deppei to affinis, from which the trend would continue along 

 certain of the lines of dispersal unchanged, and be reversed along 



