DERMAPTERA AND ORTHOPTERA 281 



our continent that is also found outside of North America (in the 

 last few decades a fair number of species of the genus have been 

 made known from eastern Asia). This distribution is paralleled in 

 part by the acridid genus Zubovskya, the blattid genus Cryptocercus 

 and also by numerous genera of trees and shrubs which have similar 

 patterns of discontinuous distribution and are now unrepresented in 

 western North America. 



Of the various genera of the Decticinae in western North America, 

 a single genus {Metrioptera, s. 1.) is shared with the Palearctic 

 region. This genus with us is a truly boreal type, not occurring south 

 of Alberta. Its nearest relative is considered by some European 

 authorities to be M. iissuriana of the Soviet Far East. Of truly 

 Sonoran development we would regard the genera Eremopedes and 

 Pediodedes. Genera limited to, and probably developed in, the very 

 arid western section of the Sonoran are Anoplodiisa and Ateloplus. 

 The genus Aglaothorax is limited to the Mohave Desert and the 

 Great Basin, and to the latter the exceedingly rare and local Za- 

 cydoptera is also restricted. Plagiostira, although chiefly a Great 

 Basin genus, extends southward over parts of the Arizona Plateau 

 and eastward into sections of New Mexico, and Capnobotes, which is 

 chiefly a western Sonoran type, also extends northward in mountain- 

 ous portions of the Great Basin. 



Probably originally of Sonoran origin, but now extending its 

 distribution widely over the Great Basin and the Columbia Plains, 

 and even to very considerable elevations in the Rocky Mountains, 

 is the genus Anabrus, the dreaded Mormon cricket. In the north- 

 western United States are two endemic decticid genera, Pemnabriis 

 the economically important coulee cricket, and Apote, which is 

 chiefly localized in the Columbia Plains, but reaches southern 

 British Columbia and is apparently restricted in its occurrence. It 

 is possible that further study may show that both Anabrus and 

 Peranabrus have Palearctic relationships, and the same also may be 

 true of Apote. Material for such study is now available and will be 

 used in the near future. 



In the broadly Pacific area from British Columbia to southern 

 California are a number of clearly endemic genera of Decticinae, 

 such as Neduba, which often is taken on the ground in heavy conif- 

 erous forests from British Columbia to the mountains of southern 

 California, and Idiostatus, from more arid regions of the same 



