122 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL.XX. 



area intercalata always, even in macropterous forms of dimorphic spe- 

 cies, extending- somewhat, generally considerably, beyond the middle 

 of the tegmina. Hind femora moderately long and slender, the infe- 

 rior genicular lobe with at least a darker basal spot or transverse 

 band, the hind tibiae with a variable number of spines (generally nine 

 to fourteen) in the outer series, by rare exception eight only. Abdo- 

 men more or less compressed, the sides of the first segment with a dis- 

 tinct tympanum, the extremity in the male more or less sometimes 

 strongly clavate, usually considerably recurved, the subgenital plate of 

 variable form, but always with the lateral margins ampliate at the 

 base and with no distinct apical tubercle, though not infrequently api- 

 cally produced or subtuberculate and frequently tumescent; cerci 

 exceedingly variable in form, often enlarging apically, always lamellate 

 excepting (the lakinus series three species) where they are basally 

 globose, never styliform, rarely (the puer series two species) in the 

 least substyliform, generally incurved and of about the length of the 

 supraanal plate; furcula usually developed and to a very variable 

 extent, and with variable form; pallium rarely exserted; ovipositor of 

 female generally fully exserted. 



The type of the genus is Acridium femur -rubrum De Geer. 



The number of species of Melanoplus is so exceedingly great that I 

 have endeavored to display their relationships in part by separating 

 them into groups. Noticing how seldom the characteristic parts of the 

 male abdomen agreed in the short-winged and long- winged forms, not- 

 withstanding that one would look for their close agreement, I have first 

 divided them in the following table into those which are fully equipped 

 with ample organs of flight and those in which these organs are more 

 or less undeveloped, and then have subdivided each according to other 

 characteristics, endeavoring thus to bring into close contiguity those 

 which appeared to be most nearly allied. I was not a little surprised to 

 find in how few instances it was possible to combine the brachypterous 

 and macropterous species in any one of these groups. Even in most 

 of these, and especially in the dawsoni series (itself somewhat heter- 

 ogeneous en either side), the collocation is rather forced. The groups 

 into which I have divided the macropterous forms are far more nat- 

 ural than those of the brachypterous species, and the portion of the 

 table relating to the former is therefore much more satisfactory than 

 the other. I have more than once completely remodeled that relating 

 to the brachypterous species, but with no greater success than in that 

 now presented. 



Much to my surprise, I find but a couple of species in this genus (M. 

 dawsoni, M. marginatus) in which there is complete dimorphism shown 

 in the full development on the one hand and extreme abbreviation on 

 the other of the organs of flight. In other species, especially in M.fasci- 

 atus and M. extremis, there is considerable variability, but nowhere 

 else is it carried to this extreme. It is, however, found in DendroiettiXj 



