PROCEEDINGS OF THE NATIONAL MUSEUM. 



species from South America; but in the present paper full consideration 

 will be given only to the North American species; a table will, however, 

 be added for the determination of the Old World species in their place, 

 and the South American forms will be merely tabulated at the close. 



Geographical distribution. The Melanopli are an almost exclusively 

 American group; a single genus, Podisma, is represented in the Old 

 World (and more abundantly than in the New) north of 35 north lati- 

 tude. With that exception almost all the genera and species are confined 

 to North America. South America possesses four genera (not included in 

 the present paper) Dichroplus, Scotussa, Scopas, and Atrachelacris, with 

 about twenty known species mostly referred to Dichroplus, besides 

 ParadichropluSj with four species in Paraguay. The remaining genera 

 are exclusively North American, but eleven of them Netrosoma, 

 Phaedrotettix, Conalcaea, Barytettix, Phaulotettix, Geplialotettix, Rhab- 

 dotettix, Cyclocercus, Sinaloa, Aidemona, and Philocleon, with nineteen 

 species, besides two species of the South American genus Paradichro- 

 plus, are found exclusively in Central America and Mexico, or only pass 

 the borders of the United States narrowly. 



All of these Central and South American genera (with the single 

 exception of Philocleon) belong to the division of Melanopli in which 

 the lateral margins of the subgenital plate of the male are not at all 

 ainpliateatthebase; and they corn prise all but three of the genera belong- 

 ing to that section, these three being Gymnoscirtetes with one species in 

 Florida, Hypochlorawith one species from the Canadian border to Kansas 

 and Colorado, and Campy lacantha with four species, three ranging 

 from Nebraska to Texas and one found in Mexico. The great bulk of 

 the species and most of the genera (including all but one Philocleon 

 of those belonging in the section with ampliate basal margins to the 

 subgeuital plate) are confined to the United States and Canada, where 

 they form one of the dominant types of Acridiidae. 



This division, that with ampliate basal margins, is represented (apart 

 from Philocleon with its single species) by fourteen genera and one hun- 

 dred and seventy-nine species, of which only four genera occur south 

 of our border, with thirteen species confined to Mexico, and twelve 

 others found both in Mexico and the United States; leaving ten genera 

 wholly, and four others almost wholly, belonging to the more northern 

 region, with one hundred and sixty-six species. No species of either 

 division are found in the Antilles. 



With trifling exceptions, then, the division with nouarnpliate basal 

 margins to the subgenital plate is characteristic of Central and South 

 America or subtropical and tropical America while the other divi- 

 sion, vastly more important, is characteristically temperate North 

 American, with one outlier in temperate Europe Asia. 



The dominant genus is Melanoplus with one hundred and thirty one 

 species described in the present paper; a number more are known to 



