DERMAPTERA AND ORTHOPTERA 269 



Old World genera than has yet been determined. Prumnacris and 

 Buckellacris are both distinctly northern montane types: Prumn- 

 acris occurs chiefly in the northern Cascades, and Buckellacris 

 extends from the same range northward to the Chilcotin area of 

 British Columbia, and eastward over the northern Rockies to south- 

 eastern Idaho. In the Rockies of the northern United States and 

 southern Canada, and in adjacent parts of Washington and the 

 northern Sierras of California, the distinctive genus Asemoplus 

 is localized, and in the southern Sierras only at or near timberline 

 do we find Hebardacris, which has nearest affinity to Bradynotes. 

 All these montane genera are clearly of relative antiquity, and 

 probably survived Glacial conditions by retreating moderate 

 distances before the advancing sheets or the encircling spread of 

 mountain glaciers. Some of them seem to have reoccupied only 

 limited sections of suitable terrain which was heavily glaciated. 



(3) Subfamily Oedipodinae. The Oedipodinae comprise a large 

 number of chiefly ground-dwelling grasshoppers, some of which have 

 become of economic importance. The subfamily is poorly represented 

 in the Southern Hemisphere, and is best developed in Eurasia and 

 North America. In South America its members are limited to a few 

 genera, one of which, Trimerotropis, is markedly developed in North 

 America, while another, Heliastus, narrowly enters our territory. 

 The maximum diversity of the subfamily is in semi-arid grass- 

 lands, although it is also well represented in true deserts and semi- 

 deserts, and a number of types occur in more humid grasslands and 

 bush country; a very few are more partial to wooded areas. Some 

 of the species live in the most arid environments to be found in this 

 continent and in similar areas in Asia and North Africa. Some are 

 governed in their occurrence by the presence of favorite food plants, 

 but on this point our information is less conclusive than for some 

 other grasshoppers. Apparently most, if not all, of the North 

 American genera have developed in our territory or in northern 

 Mexico, although the possible relationship of a few of the genera to 

 those of Central Asia remains to be more accurately determined. 

 Broadly speaking, however, the oedipodine fauna of North America 

 is autochthonous. A number of the genera probably originated in the 

 Sonoran region of our southern Great Plains, the southwestern 

 United States, and northern Mexico. Certain of these genera have 

 extended their ranges into the more eastern United States and 



