1919] Distribution of Insects 9 



Sierras. The fourth species, N. diversa Lee. is of a yellowish 

 color and is confined to the sea coasts of Washington and 

 Oregon. The only close relatives that these four have are 

 certain species found in the more eastern part of the Himalayas 

 and in northeastern Asia. The last beetle to be mentioned in 

 this connection shows another peculiarity of distribution due 

 to the retreating ice. This is Pterostichus brunneus Dej., a 

 species first described from Sitka on Baranoff Island, later 

 found on Orcus Island near the mouth of Puget Sound and no 

 doubt occurring on other islands in the same general region, 

 and on the mainland only high up near the timber line as in 

 the Selkirks of British Columbia, on Glacier Peak and Mt. 

 Rainier in Washington, and on Mt. Jefferson in Oregon. On 

 the islands, it was left stranded, but by adaptation was able 

 to persist, while on the mainland it could preserve its natural 

 environment by merely retreating with the ice to the higher 

 levels. 



The faunas of southern origin are to be found in their purest 

 state only in the more southern part of our territory though 

 derivatives of the same do in certain regions extend quite far 

 to the northward. The best known of these is the Sonoran 

 which, when considered in its strictest sense, may be said to 

 occupy all those hot and more or less barren uplands in northern 

 Mexico and the semi deserts and drier regions of our own 

 Southwest, with extensions into western Texas, southern New 

 Mexico and Arizona, and the more desert parts of southeastern 

 California. The fauna of the Colorado Desert as well as that 

 of its more upland extension, the Mojave Desert, is typically 

 Sonoran. Certain elements of this also extend more west- 

 ward along our southern border to the coast at San Diego and 

 from the Mojave through the hot Walker Basin into the 

 southern San Joaquin Valley. Here it is to be found mainly 

 on the west side of the valley as in western Kern County and 

 in an attenuated form in southern Monterey County. Some 

 of its most characteristic beetles are among the wingless Tene- 

 brionidce, such as in the genera Edrotes, Trioropkus, Zopherus 

 and Asida, and in the wingless OtiorychincB like Ophrastes and 

 Eupagoderes, and the genus Monilema of the Cerambycidce. 



A derivative of the Sonoran fauna which is generally spoken 

 of as the upper Sonoran, though it is more accurately defined 

 as the Great Basin fauna, extends throughout the entire area 



