NO. 1124. EE VISION OF THE MELA XOPL ISC UDDER. 187 



a fourth as long- as the supraanal plate; cerci forming nearly flat plates, 

 about half as long again as broad, lying in a nearly uniform subver- 

 tical plane, generally slightly curved or bent upward, the apical half 

 slightly more compressed than the basal and narrowed by a consider- 

 able oblique excision of the inferior margin, the tip broadly rounded 

 or subtrnncate; subgenital plate roundly subpyramidal, the apical mar- 

 gin with moderate abruptness, somewhat elevated, thickened, and 

 mesially notched distinctly. 



Length of body, male, 25 mm., female, 28 mm.; antennae, male, 9 mm.,, 

 female, 8.75 mm.; tegmiua, male, 26.5 mm., female, 27.5 mm.; hind 

 femora, male and female, 14 mm. 



Two hundred and seventy- six males, 439 females. I refrain from givin g 

 in detail the localities from which I have seen specimens, both on account 

 of their immber and because, from the irregular distribution of the 

 insect in different years, such details would have little value without 

 dates, which are not always accessible; farther on, however, I give all 

 that are of special interest. 



The name of this species is to be credited to Mr. P. R. Uhler, who 

 placed it in his collection thirty or more years ago and communicated 

 it to various persons, who used it. sometimes in an incorrect form. The 

 original specimens were received from Mr. Robert Kennicott, and were 

 obtained by him from a migratory horde which settled in the then Red 

 River settlements, now Winnipeg and vicinity, Manitoba. On Mi\ 

 Uhler's generous transfer of his collection to me, these specimens, with 

 their history, came into my possession, and I now have them with his 

 original labels. One has been placed in the National Museum. 



It was thus known from the start as a migratory insect, and com- 

 paring it with any species of the genus one would at once be struck 

 with the greater length of the tegmiua and wings. These were meas- 

 ured by Riley; in forty-eight males the tegmiua extended beyond the 

 abdomen 5 to 10 mm., with an average of 7.6 mm. ; in ninety-nine females 

 they ranged from 3 to 10 mm. beyond the abdomen, the average 6.7 mm. 



It is now well known as the "Rocky Mountain Locust" or destructive 

 locust of the States in the western half of the Mississippi Valley. It 

 has been more written about than any other American Orthopteroii, and 

 was specially discussed by the United States Entomological Commission, 

 organized to devise methods of checking its ravages after a study of its 

 natural history. It forms the almost exclusive subject of their first 

 report, and occupies a considerable space in their second. Although a 

 considerable body of the evidence adduced by them is contradictory 

 and in part of doubtful application to this particular species, their con- 

 el tisio;iis are in very large measure well founded. As appears from a 

 study of their work and other available material, the following conclu- 

 sions may be fairly drawn: 



(1) Tho home of the species is in favorable localities in the elevated 

 region of the Rocky Mountains or immediately bordering it from the 



