230 NORTH AMERICAN OEDIPODINAE (ORTHOPTERA; ACRIDIDAE) 



but as it is desirable for various reasons to bring out the descrip- 

 tions of the new forms ah'eady located, and certain of our con- 

 clusions relative to the relationship of some of the previously 

 known ones, we are introducing them in the present form. 



The tj'^pes of all the new forms here described are in the Hebard 

 Collection, and the paratypical material is in that collection 

 and that of the Academy of Natural Sciences of Philadelphia. 



Our earnest thanks are due our colleague, Mr. Hebard, for 

 many helpful suggestions, and also for the gift of the colored 

 plate accompanying this paper. 



The Haydenii Group of the Genus Derotmema 

 We find this group consists of three geographic races or sub- 

 species, for which the oldest, and consequently the specific, name 

 is haydenii of Thomas.^ Scudder's later cupidineum^ is a pure 

 synonym of haydenii, as type examination shows. Saussure's 

 hrunnerianum^ is another pure synonym of haydenii, which latter 

 name was apparently unknown to Saussure at that time. Typi- 

 cal haydenii is the race of the Great Plains region from Montana 

 to New Mexico. 



In the Great Basin and Snake River regions we find a related 

 form which intergrades with haydenii haydenii in Wyoming, and 

 to this Saussure's name rileyanum'^ is applicable, as material from 

 the type locality and the original lot shows. Scudder,^ by an 

 interpretation of his cupidineum not warranted by his original 

 description or material, shifted his name to this Great Basin form, 

 where it clearly does not belong. The Great Basin race must be 

 known as Derotmema haydenii rileyanum. 



In western Texas and northern Mexico we find a third geo- 

 graphic race, which occurs typical in the Great Bend country of 

 trans-Pecos Texas, north to Marfa and Sierra Blanca, occasionally 

 not fully typical at the latter locality, and, at Marathon, Texas, 



* Oedipoda haydenii Thomas, Ann. Rep. U. S. Geol. Surv. Terr., v, p. 460, 

 (187V). ["Above Fort Fetterman on the North Platte," Wyoming.] 



2 Derotmema cupidineum Scudder, Ann. Rep. Chief of Engineers, 1876, p. 

 513, (1876). [Northern New Me.xico.] 



^Derotmema brunnerianum Saussure, Prodr. Oedipod., p. 155, (1884). 

 [Colorado.] 



* Derotmema rileyanum Saussure, Prodr. Oedipod., p. 156, (1884). ["Salm 

 County" [Salmon City], Idaho.] 



5 Proc. Amer. Acad. Arts and Sci., xxxv, no. 19, 391, (1900). 



