NORTH AMERICAN ACRIDHD^E. 13 



They are here put forth as a suggestion and stimulus to further 

 research. 



Genera of boreal origin and distribution. Of the genera of 

 Acridiidse occurring in eastern North America six are boreal: 

 Chlocaltis, Stenobothrus, Mecostethus, Camnula, Circotettix, Podisma. 

 Of these Mecostethus alone is confined to the territory east of the 

 Rocky Mountains, so far as known. Stenobothrus, Mecostethus, and 

 Podisma are Old World genera, and, with Gomphocerus, found 

 among the Rocky Mountains, constitute a reminder of circumpolar 

 land communication. If to these we add Tettix, which is cosmo- 

 politan, we shall have considered all the genera common to Europe 

 and North America, with the exception of Schistoccrca, austral in 

 distribution, one species of which is believed to have crossed from 

 South America to the Old World. 



Genera of austral origin and distribution. In this group are 

 found six which are peculiar to the Gulf strip of the Lower Austral 

 zone or its immediate vicinity: Paxilla, Rhadinotatum, Macneillia, 

 Gymnoscirtetes, Eotettix, Aptenopedes. Besides these, Dictyophorus, 

 Arnilia, and Leptysma extend further westward in the Lower 

 Austral zone. 



Others of austral origin and distribution are : Neotettix, Para- 

 tettix, Apotettix, Tryxalis, Mermiria, Syrbula, Eritettix, Ambly- 

 tropidia, Dichro morpha , Clinocephalus t and Paroxya. Of these 

 all but Paratettix, Apotettix, Tryxalis, Mermiria, and Syrbula are 

 confined to the east. Psinidia and Scirtetica, likewise confined to 

 the east but probably of Sonoran derivation, are doubtless of 

 austral origin. Dissosteira, Hippiscus, Spharagemon, Trimerotropis, 

 Arphia, and Hesperotettix, of extended distribution both latitudinally 

 and longitudinally, are probably of austral Sonoran origin, though 

 some species have become adapted to boreal conditions. Chorto- 

 phaga and Encoptolophus , possibly Arphia also, there is reason to 

 think, may have originated in the east. Ageneotcttix, Phcetaliotes, 

 and Mestobregma have apparently but recently entered our territory 

 from the west and as yet occupy but a small portion of it. The 

 place of origin of Pseudopomala is questionable. Schistocerca and 

 Orphulella are undoubtedly of austral origin, though containing 

 species which reach a high altitude and latitude. The same is true 

 of Tettigidea, and possibly of Nomotettix^ both of which seem to 

 be typically eastern in distribution. Melanoplus, the dominant 

 North American genus, covers the continent from Labrador to 

 Mexico, from Alaska to Florida, and contains boreal and austral, 

 eastern and western, and humid-land and arid-land species. 



