168 NORTH AMERICAN MELANOPLI (ORTHOPTERA) 



PART VII. THE INDIGENS GROUP OF THE 

 GENUS MELANOPLUS 



So similar are the species of this group in many features and 

 so much individual variation is shown in several of the limited 

 number of characters by which the species and races are distin- 

 guishable that their proper association has always been most 

 difficult. It was for this reason that we have postponed a final 

 report on them until we have gone over all the species of the 

 short-winged Melanopli, examining the penis of each with a 

 view to finding out just how much help the characters of that 

 organ might afford. Nowhere in these studies has the structure 

 of the penis proved more valuable in placing the actual number 

 of species and races represented. 



We find that in past literature the confusion has been very 

 great, and though all existing synonymy was correctly estab- 

 lished by us in 1928, 1 we at that time not only made many 

 errors in referring to indigens and oregonensis triangularis speci- 

 mens which were actually otherwise referable, but we also recog- 

 nized four races of oregonensis, whereas that species has but a 

 single northern race, oregonensis triangularis, while marshalli 

 represents a distinct though very closely related species of which 

 ascensor is a weakly defined but apparently separable western 

 race. Although it is evident that we made a series of serious 

 errors we can state definitely that, without recourse to the char- 

 acters of the penis, little better could ever be expected. Thus 

 in the material referred incorrectly to indigens all other features 

 except those of the penis showed only differences which might 

 easily and were then believed to indicate mere individual varia- 

 tion and the individual variation in the shape of the supra-anal 

 plate is so unusually great that at that time we referred in- 

 correctly to oregonensis triangularis those specimens in which 

 the supra-anal plate is very much shorter than is normal for 

 indigens. With the differences of the penis as a guide, however, 

 it is now evident that the richness of coloration of the ventral 

 surfaces of the caudal femora in those specimens is a safe index 

 in distinguishing them from oregonensis triangularis, which dif- 



1 Proc. Acad. Nat. Sci. Phila., lxxx, pp. 266 to 271. 



