1919] Distribution of Ijisects 5 



the alternate elytral intervals more reduced or irregular; in 

 southwestern Oregon and northwestern California, it occurs 

 with a more angulate prothorax, still more modified elytra, 

 and with the male tarsi somewhat changed ; while in the southern 

 part of its range, in Mendocino and northern Sonoma County, 

 California, it appears as a much larger insect and much modified 

 in every regard. In Pterostichus amethystinus Dej. we have a 

 species with bluish elytra which extends from Alaska to middle 

 Mendocino County, California. South of this, it is replaced 

 by P. sciitellaris Lee, a species which has absolutely the same 

 habitat and only differs from the preceding by being all black. 

 It extends into Monterey County, California. Among the 

 ElateridcE, we have numbers of species which like Athous 

 ferruginosus Esch., have a black phase within the southern 

 maritime area. In the genus Silis, the species and varieties 

 found along the coast and in the high mountains of the Pacific 

 Coast are mostly black, whereas in the interior lowlands they are 

 yellow. Among the Rhynchophora, we have one, Rhynchites 

 bicolor Fab., one of the most widely distributed weevils in 

 North America which has its only known black phase in the 

 middle coastal belt of Oregon. 



A second and more greatly modified portion of the Van- 

 couveran fauna is that which inhabits a strip of country that 

 starts in the west central part of Oregon, runs south and south- 

 east, including all of the moderately elevated mountains in 

 Southern Oregon and Northern California, and extends along 

 the western flanks of the southern Cascades and Sierras into 

 Southern California and with breaks, also into the San Pedro 

 Matir of Lower California. This subfauna I would call the 

 Sierran. It occupies much of the same country as that covered 

 by the western yellow pine, and though it receives many species 

 from those faunas found immediately above and below it, is in 

 no sense a transitional one as often called. It is a distinct 

 subfauna and a direct offshoot of the Vancouveran. Its species 

 are almost always either like those to be found in the pure 

 Vancouveran or are derivatives of the same. In the northern 

 area of the Sierran subfauna, certain species show a strong 

 tendency to break up into many weak races which are more or 

 less limited to various small areas. This unstableness is no 

 doubt partly due to climatic and partly to topographical 

 conditions, for the country is much broken up, there being many 



