58 OETHOPTEEA. 



AMPHITOKNUS, McNeill. 



Stenobothrus, Thomas, Prelim. Rep. U.S. Geol. Surv. Mont. p. 465 (1872) ; Syn. Acrid. N. Amer. 



p. 83 (1873) (nee Fischer). 

 Amphitornus, McNeill, Proc. Dav. Acad. Nat. Sci. vi. p. 223 (1897). 



This small genus is confined to the western half of North America, where it is 

 represented by two recognized species which may be separated as follows : — 



A 1 . Median carina of the pronotum severed decidedly behind the middle . 1. ornatus, McNeill. 

 A 2 . Median carina of the pronotum cut by the last transverse sulcus but 



little behind the middle [2. bicolor, Thorn.] 



l. Amphitornus ornatus, McNeill. (Tab. I. figg. 13, 13 a, 2 .) 



Amphitornus ornatus, McNeill, Proc. Dav. Acad. Nat. Sci. vi. p. 225 \ 



Stenobothrus coloradus, Koebele, Bull. no. 22, Div. Ent., U.S. Dept. Agric. p. 94 (1890) 2 . 



Ilab. Noeth America, Western Texas, Southern New Mexico, Arizona, and Cali- 

 fornia 1 2 . — "? Mexico, Durango. 



There are no examples of this species before me from Mexico territory, but some 

 years ago I noticed an insect in numbers in the State of Durango which appeared to 

 belong to it. Unfortunately none were taken at the time. 



A. bicolor, Thomas, is more northern in its distribution. 



OPEIA, McNeill. 

 Opeia, McNeill, Proc. Dav. Acad. Nat. Sci. vi. p. 214 (1897). 



This is another strictly American genus that seems to be restricted to the arid and 

 semiarid regions of the tablelands of Mexico and the south-western portions of the 

 United States. While the collections at hand indicate rather numerous forms, but two 

 of them appear to occur beyond the Mexican border within the United States. One of 

 these, 0. testacea, Scudder, is rather local in its distribution, and, so far as recorded, is 

 confined to the southern half of California. The other, 0. obscura, Thomas, is distri- 

 buted over the plains from the Rio Grande in the south to the Saskatchewan in the 

 north, and is partial to certain low-growing grasses. The Mexican forms are mostly 

 short-winged, and with a single exception appear to be slightly more robust than the 

 two just mentioned. 



There is little doubt that some close collecting at various points in the plateau- 

 regions of Mexico would bring to light several additional species. The known forms, 

 along with those now described, may be distinguished as follows :— 



Table for separating the Species of Opeia. 



A 1 . Tegmina fully developed, reaching at least the tip of the abdomen, their 

 apices rounded. 

 b\ General colour darker in the female, sometimes green, varied and 



