GEOLOGICAL SURVEY OF THE TEREITORIES. 431 



niveus, Stenopelmatus fasciatus, Udcopsylla rohtista^ EpMppityilia gracilipes^ 

 Calopteims hivittatus. C. q)rofus, C. occidentalism Pezotettix obesctj (Edipoda 

 coralUpes, (E.Hal demo nniij (E.^cincta^ CE. Montana, (E. Carolina, Stauro- 

 notus Elliotti, tStcnohotlirus maculipennis, and 8t. hrunneus. 



Those found in both the middle and western districts are few, but it 

 must be borne in mind that the collections in these two districts have 

 been small, hence the means of coDiT)arison are very limited. I have 

 given Calopienus femur ruhrwn and (Edipoda rugosa to the western dis- 

 trict on the authority of Walker, but I have strong doubts as to the 

 correctness of this. 



The very great preponderance of the numbers in the eastern district is 

 owing chiefly to the fact that the collections have been much larger 

 and over a much greater area in this district than in either of the 

 others. Another reason is, that I have limited to the eastern district 

 those concerning which I have any doubt. My collections, and those 

 to which I have had access, were not separated as accurately in regard 

 to these districts as they should have been, hence I have placed them 

 only in the districts to which I know they belong. 



But notwithstanding this uncertainty as to the comparative numbers 

 of species in the eastern and middle districts, yet it is evident the pre- 

 ponderance is strongly in favor of the former. 



I think we may conclude with safety that the eastern limit of the 

 arid plains which lie west of Iowa, Missouri, and Arkansas is a more 

 rigid boundary to the orthopterous fauna than the dividing range of the 

 Eocky Mountains ; while on the western side the Sierra Nevada Eange 

 forms an equally rigid boundary. This corresponds with the distribu- 

 tion of the coleopterous fauna of the United States as shown by Dr. 

 LeConte, (Smithsonian Contributions to Knowledge.) 



I add the following notes in regard to the range of some of the more 

 iinportant species, which may be useful in future investigations : 



Gryllus ahbreviatus is found scattered over the plains at the base of 

 the mountains from Southern Colorado to Central Wyoming. I also 

 found specimens in Northern Utah, but when I reached the rim of the 

 basin and passed into Southeast Idaho, entering the Snake Eiver Basin, 

 most of the specimens of Gryllus taken proved to belong to G. luctuosus. 



Anabrus purpurascens is found, not abundantly, but at certain elevated 

 points from Northern New Mexico to Montana, along the east base of 

 the mountains, but I have met with no specimen Avest of the range in 

 the middle district, though Mr. Uhler gives Washington Territory as a 

 locality, on the authority of Dr. Suckley. It is also found as far south 

 as Texas, and as far north as Eed Eiver, in Northern Minnesota. A. 

 simplex appears to be confined to the middle district, as I have not met 

 with it east of the range, and have seen no notice of it being found 

 either in the eastern or Avestern districts. Dr. Scudder, who examined 

 the Ortlioptera collected by Professor Hay den, in Nebraska, does not 

 mention it in his list; nor did Mr. C. E. Dodge have it among his col- 

 lections made in Nebraska, Colorado, Kansas, and Indian Territory ; 

 nor is it among the collections in the Agricultural Department made 

 east of the Eocky Mountains. Hence I think we may safely conclude 

 that it is confined to the west side of the range. But what it lacks in 

 range is made up in numbers, ibr in the northern x)art of Salt Lake 

 Basin and southern part of Idaho, the only points where I have met 

 with it, it is to be seen in armies of myriads. But a fuller account of 

 it will be found in the list. 



Stowpelmatus fasciatus is found scattered sparsely over Wyoming, 

 Northern Utah, and Southern IdahOj but does not appear to occur iu 



