DIPTEKA. 307 



L Heteropogon rejectus, sp. n. 



5 . Black. Front opaque brown. Face gently convex, clothed with white bristles and hairs, sparsely inter- 

 mixed with black. Style of antennas about one-half the length of the third joint. Mesonotum with 

 a median, deep brown stripe, separated from the subvittate spots of the same colour on each side by a 

 narrow whitish stripe, all opaque. Scutellum opaque brown ; near the margin shining blue-black. 

 Abdomen bare ; the posterior angles and lateral margins of the segments, more broadly so posteriorly, 

 reddish-yellow (the yellow may extend across the hind margin of the posterior segments narrowly). 

 Femora black, their tip and the tibiae wholly red ; the tarsi a little darker red. Wings nearly hyaline, 

 with small brown clouds on the cross-veins and the furcatioa of the third vein. Length 10 millim. 



Hah. Mexico, Venta de Zopilote in Guerrero (H. H. Smith). 



A single female. This species is allied to II. lantus, Loew, but will be at once 

 distinguished by the absence of pollinose cross-bands on the abdomen and the yellow 

 margins of the segments. The immediate base of the wings is brownish. 



TOWNSENDIA. 



Townsendia, Williston, Kans. Univ. Quart, iv. p. 107 (1895). 



Head broad, much wider than high. Front very broad above, about three-fourths the width of the head,. 



narrow below, the sides gently convex, only moderately excavated ; nearly bare, with some bristles at the 



vertex and on the ocellar tubercle. Face narrow, with parallel sides, flat ; much receding, not at all 



visible in profile, with a thin row of bristles on the oral margin, otherwise wholly bare. Antennae not so 



long as the head, inserted near the middle of the head as seen in profile; first joint shorter than the 



second, the second about as broad as long; third joint longer than the first two together, gently tapering 



from near its base ; style slender, divaricate, about half the length of the joint. Proboscis short. Thorax 



moderately convex above, with bristles on the posterior part. Scutellum with a row of thin bristles on 



its margin. Abdomen elongate, its sides nearly parallel, moderately flattened, bare. Legs moderately 



stout; the first two joints of all the tarsi a little incrassate ; no spur on the front tibiae. Wings long, 



narrow toward the base ; axillary cell narrow, without anal angle ; alulae wholly wanting ; disoal coll long 



and narrow ; penultimate section of the fourth vein a little shorter than the ultimate ; the third vein 



from the discal cell, that separating the third and fourth posterior cells, absent, and therefore but four 



posterior cells present ; marginal cell open. 



This o-enus is remarkable on account of the small size of the typical species, the 



broadness of the front, the narrowness of the wings at the base, the absence of the 



alulae, and the presence of but four posterior cells. In one of the two specimens from 



which this description is drawn there is a very slight angulation of the vein at the 



posterior part of the discal cell where the missing vein should have its origin, but even 



this is wholly wanting in the other example ; I cannot believe that this character should 



be regarded as very important, as it is not at all improbable that species may be 



discovered in which the neuration is normal. The very broad front, the receding face,. 



and the narrowness of the base of the wings are, I believe, the most essential characters 



of the genus, which is named in honour of Professor C. H. T. Townsend, well known 



for his dipterological writings. 



1. Townsendia minuta. (Tab. V. fig. 19, s .) 



Townsendia minuta, Willist. Kansas Univ. Quart, iv. p. 107 \ 



A Black- front and face thickly white-pollinose ; mystax white. Antennae black. Mesonotum opaque 



2 r 2 



