274 J. A. G. REHN 



relative of Aeropedellus, but without Old World relatives, is Brun- 

 eria, which is a northern type, usually found under Boreal, or even 

 Hudsonian, conditions, from southern Canada sporadically and 

 very locally south in the Cascade-Sierran uplift to northern Califor- 

 nia and in the Cordilleran massif at least as far as southern Utah. 

 It appears to have developed in the territory where it now occurs, 

 with greater diversity in the Cordilleran section than elsewhere. 

 Three of our acridine genera, Amblylropidia, Orphiilella, and 

 Rhammatocerus, are clearly of Neotropical origin. All have a far 

 greater specific development and areal extent southward than in 

 our area, extending to southern Brazil and Argentina. Amhlytro- 

 pidia is only narrowly represented along our Mexican border by 

 one of a number of Mexican species, although a distinct endemic 

 species occurs rather broadly over the southeastern United States. 

 Rhammatocerus is similarly represented along the Mexican border, 

 but not elsewhere in North America. Both of these genera apparently 

 are more recent intrusives than Orphulella, which is broadly present 

 in North America from Atlantic to Pacific. Because of its habitat 

 preferences Orphulella is of much more localized occurrence in the 

 western part of its range than in the East. A considerable number 

 of the genera of the subfamily in North America, including Paro- 

 pomala, Acrolophitiis, Amphitornus, Opeia, Cordillacris, Phli- 

 bostroma, Boopedon, Ageneotettix, Drepanoptertia, and Aulocara, 

 I would regard as autochthonous in our Great Plains, the adjoining 

 Texas Sonoran area, or the Sonoran areas to the westward. Other 

 genera, including Achurum, Eremiacris, and Morseiella may, with 

 reasonable assurance, be regarded as having developed in Mexico, 

 and species there found, or closely related ones since evolved, 

 occur on our side of the border. Another genus that should be 

 placed in this category is Syrbida, although it apparently entered 

 our territory quite some time in the past, as one of its species, 

 which also is distributed over much of Texas, is broadly established 

 in our more southern and southeastern states. The genus Mermiria 

 is represented in the West by four of the well-difi'erentiated lines 

 that it has evolved in the United States. In all probability this 

 genus developed in the Sonoran region, spread broadly over the 

 Campestran, and then extended its range into the southeastern and 

 central states, where three of its lines occur. One of its most dis- 

 tinctive species, M. texana, is present on both sides of the Mexican 



