SCUDDER ON FOSSIL INSECTS. 751 



remnant of a wing, but the portion of the venation preserved is only suf- 

 ficiently characteristic to enable us to judge that it belongs in this family. 

 The thorax is strongly arched, and the full and tapering abdomen indi- 

 cates a female ; the head is gone ; the thorax and abdomen are 3.5"™ 

 long, and the wing probably 3""" long. 



Another of them, '^o. 4114, has a portion of the base of a wing, in 

 which the forking of the fifth and sixth longitudinal veins is very close 

 to the base, as in Saclcenia, but nothing more can be said concerning 

 it ; the thorax is very globular and the abdomen short. 



Length of thorax and abdomen 3.65™"". 



The third species is represented by two specimens on one stone (No. 

 4205) which came from the buttes opposite Green Eiver Station, and is 

 the only fly which had the slightest value found in four days' search. 

 One of the specimens is a pupa and the other an imago, ai)parently of 

 the same species and distinct from either of the preceding, with a longer 

 thorax and slenderer abdomen, provided with large ovate anal lobes. 



Length of thorax and abdomen 5"^™. 



ASILID^. 



StenocincUs (<tt£vo?, xiy/.Xc!;), nov. gen. 



This genus of Asilidw is founded wholly upon characters drawn from 

 the neuration of the wing, the only portion of the insect preserved. It 

 falls into the group of Dasypogonina^ in which the second longitudinal 

 vein terminates in the margin apart from the first longitudinal vein, 

 instead of uniting with it just before the margin. It is not very far 

 removed from Dioctria, but differs from it and from all Asilidm I have 

 examined in that the third longitudinal vein arises from the first before 

 the middle of the wing, instead of from the second longitudinal vein 

 after its emission from the first; the first longitudinal vein has there- 

 fore two inferior shoots, giving the wing a very peculiar aspect, and 

 causing it to differ radically from all other Asilidw ; indeed, it would be 

 hard to know where to look for a similar feature among allied Diptera^ 

 unless it be in the anomalous group of Cyrtidm. The wing is very slen- 

 der, and all the cells unusually elongated, which also gives it a unique 

 appearance. 



StenocincUs anomala. — This species is represented by a single frag- 

 ment of a wing (No. 4143), which I found in the Green Eiver shales. 

 Nearly all the neuration is preserved ; but the posterior margin is 

 absent, and the length of the cells which border upon it cannot be 

 accurately determined. The insect was evidently small, with a long and 

 slender wing. The auxiliary vein terminates slightly beyond the mid- 

 dle of the costal margin ; the first longitudinal vein runs up toward the 

 margin where the auxiliary vein terminates, and follows along next the 

 edge far toward the tip, as usual in this group ; the second longitudinal 

 vein originates from the first a little way before the middle of the wing, 



