No. 453-] DISTRIBUTION OF CICINDELA 



653 



sider C. willistoni survivor of an early stock which, (hirin-- the 

 Tertiary period, inhabited the present Rocky Mountain iv-ion 

 and in all probability the adjacent districts to tlic rast and west 

 at the time of the great extension of the Tcrtiai) lakc>. ( . 

 tvillistoni is much better differentiated from the races of ( < rlto 

 than those races are among themselves. 



My conclusions are these: That in C. echo (with its several 

 races, including C. pseudoseiiilis) and C. zvillistom, wc ha\ e two 

 branches of a stem which were probably separated by some ot 

 the orographic movements which gave rise to the upheaval of 

 the Wasatch and Rocky Mountains. That this stem form was 

 a littoral species and the branch remaining in the Great Basin 

 was carried over the interval between the dissolution of the Ter- 

 tiary lakes and the appearance of the great Pleistocene lakes by 

 clinging to the borders of springs and other bodies of water. 

 That with the growth of Lake Bonneville and Lake Lahontan 

 and the contemporaneous filling by water of the smaller basins, 

 it spread over the whole habitable area between the Wasatch 

 and the Sierras. The subsequent desiccation of the greater 

 part of the Lahontan and Bonneville basins left a series of 

 smaller lakes of varying permanence and more or less complete 

 isolation. Local conditions, acting on the members of colonies 

 of the beetles thus separated from their neighbors, have given 

 rise to variations of different kinds and certain of these \ana- 

 tions have been preserved and accentuated through this isolation. 

 As a consequence, we have the phenomenon ot local races, 

 strongly or slightly marked according to the strength ol the 

 conditions exciting variability and to the conii)aralive c egiee o 

 isolation of the colony after a certam character had mate it.s 

 appearance. Owens Lake and Honey Lake, having been long 

 since separate from the larger bodies and presuniabl\- subjected 

 to different conditions, climatic and otherwise, because of then- 

 proximity to the Sierras, have at length produced upon their 

 shores racial types which are easily distinguished fiom eac 1 

 other and from the forms found farther east. 



If the species of Cicindela used in illustration were alone in 

 presenting the general phenomena noticed, one might well dou )t 

 the sufficiency of the evidence adduced in sui)i)ort of the toie^<»ing 



