/ • 

 720 GEOLOGICAL SURVEY OF THE TEERITOEIES. 



(Edipoda discoidea, Serv. In that from East Tennessee I had the plea- 

 sure of finding the first specimen of Fyrgomorpha I have seen; the 

 species is described in my Synopsis. In Professor Glover's collection I 

 found a new species of Tryxalis, the first, so far as I am aware, that has 

 been fonnd in the United States ; also Stenacris chlorizmis, Walk. I at 

 first overlooked Walker's description, and placed it among the cylindri- 

 cal Opomala as a new species. If this genus as established by Walker 

 be retained, it will be necessary to remove other species from Opomala 

 and place them here ; and the position of the eyes will then be the only 

 distinguishing feature of Mesops. 



(Edipoda plimnicoptera^ Germ. 



I met with this species (June 21) in Southern Dakota, between Tank- 

 ton and Springfield, (Bon tlomme County.) The wings, though usually 

 of the bright red common to this species, are frequently yellowish, with 

 but a faint reddish tinge. These specimens vary slightly from the usual 

 type in the form and size of the spots of the elytra, the variation being 

 toward (E. corallipes, Hald. 



Oil. discoidea.Serv.; (E. rugosa, Scudd.; (E. corallipes, Hsdd.; (E. Ralde- 

 mannii, Scudd. ; (E. paradoxa, Thos. 

 My investigations the past season have increased my doubt in respect 

 to the distinction of these species. I have now in my collection speci- 

 mens from Mississippi, Washington City, Illinois, Nebraska, Kansas, 

 Dakota, Colorado, Wyoming, and Utah, and although there are slight 

 variations in the markings of the elytra, the rugosity of the thorax, and 

 the color of the dii^k of the wings, yet these variations fade so insensibly 

 from one into the other that tliere is no possibility of fixing the line of 

 distinction. Locality appears to have something to do with these varia- 

 tions, but does not govern them entire! y. For example, a specimen before 

 me, from Mississippi, has the disk or basal portion of the wing an orange- 

 red, while another, by the side of it, from Nebraska, has it lemon-yellow 

 with splotches of orange-red. The former is evidently the diseoidea of 

 Serville, and the latter stands about midway between rugosa and coral- 

 lipes. . When we examine them closely, the following differences are 

 .seen : taking the first as the standard, (both females,) the latter has the 

 pronotum slightly shortened, and more wrinkled and rugose, being 

 slightly tuberculate, the posterior femora a little less dilated, and 

 the contour as a general thing more full and rounded ; the spots on the" 

 elytra are a little larger, though very similar in form and position. When 

 we remember that the former is from a locality of rank vegetation and 

 moist atmosphere, while the latter is from a locality just the opposite, 

 will not this account for the differences in the pronotum ? If these 

 stood alone, I might suppose they were different species ; but pinned 

 close beside is a specimen (a female) from Southern Illinois, with the base 

 of the wings a clear bright lemon-yellow ; the pronotum, though a little 

 more shortened, yet in other respects is much like the specimen from 

 Mississippi, the siJots on the elytra enlarged, the small ones apparently 

 absorbed into the larger, the spaces also comparatively large, yet the 

 specimen is smaller than either of the others. The specimens from 

 Washington correspond very closely with the last, (from Illinois,) but are 

 rather smaller, and the pronotum is slightly more rugose on the disk. 

 jSTow, if we pass to the western plains, we find the Haldemannii of Scudder 

 and corallipes, Hald., which are absolutely so closely allied that they 

 scarcely constitute different varieties, it being sm. impossibility to dis- 

 tinguish alcoholic specimens except in extreme cases. These are of 



