144 DIPTEEA. 



before the small cross-vein, the antennae are remote at the base, and the contact of the 

 eyes in the male leaves a comparatively large triangular front above the antennae. These 

 species have — 1, nearly the same structure of the antennae : short first and minute 

 second joints; the third joint unsymmetrical, short onion-shaped, with a styliform prolon- 

 gation, not separated (so far as I can see) by a suture, and ending in a minute, sometimes 

 scarcely apparent joint, with a bristle ; or else, the incrassate base and the style of the 

 third joint become ]ess differentiated (in other words, the onion-shape becomes more 

 elongate and the style merges into it, and the minute joint with the bristle remains 

 [A. rattus]) ; 2, the same venation (with or without stump on the third vein ; anal and 

 posterior cells open) ; 3, nearly the same structure of the male genitals (quite different 

 from those of Anthrax). These species differ from Epacmus in having small, but distinct, 

 pulvilli ; a shorter proboscis, with larger, fleshy lips at the tip ; the oral opening 

 smaller, and usually filled up by the proboscis and its lips, when the former is with- 

 drawn ; the oral margin less projecting in front of the eyes, and therefore the face 

 more retreating. They differ from Lomatia and Oncodocera in having the antennae remote 

 at the base. 



For one of the species of this group Loew formed the genus Aphoebantus (Centur. x. 

 no. 39, 1872), but he did not define it so successfully as Leptochilus. He merely 

 indicates between it and certain Argyramoebce differences that are obvious, and points 

 out the presence of pulvilli and of a stump to the third vein; the latter character, 

 in this group especially, has no importance whatever. Loew had but one species, 

 Aphoebantus cervinus, and that in the female sex only. The long bristle at the end of 

 the hind metatarsus, mentioned by Loew in the specific description of A. cervinus 

 (Centur. x. no. 39), exists more or less in all the species of this group, as well as in 

 Epacmus ; the degree of its development is generally proportionate to the size of the 

 other bristles on the legs ; it becomes inconspicuous in A. rattus and A. cyclops, in 

 which the tibial spinules are but little stronger than hairs. 



I have described below nine species belonging to this group, and it is very probable that., 

 many more will be discovered in the western regions of North America. Some of these 

 species may be considered generically distinct from the typical A. cervinus, Loew; 

 but, loosely defined as the genus Aphoebantus is, I prefer to leave all these species under 

 that heading, until further discoveries suggest a better arrangement. Aphoebantus, in 

 the present, provisional sense, would answer Loew's definition, with the omission of the 

 presence of a stump, which is an untrustworthy character. 



When I proposed the genus Triodites (' Western Diptera,' p. 225) for a species of the 

 same group, I did not know the genus Aphoebantus except from the description, and the 

 stress laid by Loew on the presence of a stump prevented me from placing my Triodites 

 mus in that genus. The loose definition of Aphoebantus which I provisionally adopt 

 now would admit Triodites mus within that genus ; the adoption or rejection of the 

 genus Triodites must therefore be deferred until the final settlement of the genera of 



