SCUDDER. — NORTH AMERICAN TRYXALIX^. 45 



tapering, and distinctly longer than head and pronotum together. The 

 scai)ular area of the tegmina, as represented in McNeill's figure, is too 

 narrow ; at its widest, opposite the nexus of veins in the median area, it 

 is nearly one third the total width of the tegmina at this point. 



I have a second species of Acentetus, also represented by a single male 

 and also without antennae, taken by me at Florissant, Col., Aug. 17-22. 

 It is testaceous, marked with griseous and fuscous ; the head is testa- 

 ceous, with a pair of narrow, arcuate, diverging, fuscous occipital stripes, 

 and on each side a pair of similar but straight postocular stripes ; the 

 disk of the pronotum is griseous and the lateral lobes testaceous below, 

 passing rather rapidly into blackish fuscous above; the hind femora are 

 testaceous, more or less infuscated but not at all banded, and rufous 

 beneath, the hind tibiiB dull red. Length of body, 16.5 mm.; tegmina, 

 10.5 mm. ; hind femora, 10.5 mm. 



It differs from A. imicolor not only in color and markings, but also in 

 several structural peculiarities : The median carina of the fastigium is 

 less pronounced and indeed rather feeble ; the lateral oarinae of the pro- 

 notum, though having much the same divergence, are continuous and 

 eqsal throughout, thus requiring a modification of the generic definition 

 as given by McNeill ; the metazona is much more coarsely and deeply 

 punctate ; and the tegmina (in the male of course) have a very different 

 form, the costa being very strongly arched in the distal half and the 

 distal portion of the tegmina being much abbreviated, so that the tegmina 

 as a whole are less than three times longer than broad, instead of five 

 times as long as broail, as in A. unicolor ; the relative breadth of the 

 scapular area is even greater than in that species. It may be called 

 Acentetus carinatus. 



3. A Second Species of Opeia. 



Opeia was founded by McNeill in 1S97 (Proc. Dav. Acad. Nat. Sc, 

 VI. 214) upon a single species, Oxycoryphus obscurus Thom. I have seen 

 numerous specimens of this species coming from the Yellowstone valley 

 in Montana, Nebraska, Lakin, Kans., Sept. 1 (Scudder), Colorado, 5500', 

 7000' (Morrison), Ft. Collins, Col., Aug. 12, 25, "on Bouteloria oligo- 

 stachya" (Baker), Garden of the Gods, Col. (Scudder), Silver City, 

 N. Mex. (Bruner), and Bosque Co., Tex., "on prairies" (Belfrage), as 

 well as from Ft. Whipple, Arizona (Palmer). According to McNeill it 

 is "a species peculiar to the Great Plains." 



In 1897, Mr. A. P. Morse brought a second species from California. 



