566 GEOLOGICAL SURVEY OF THE TEREITOEIES. 



Wings (see tine figure), in- shape, are like those of most of the 

 known Blepharoceridce, having the same projecting anal angle, with a 

 rounded end (compare Loew, loe. cit., Fig. 3, 6, and 12). The venation 

 is very like that of BlepJiarocera {loc. cit, Fig. 12), only there is an 

 intercalary longitudinal vein between the first and second veins. It 

 begins near the origin of the second vein, runs alongside of the first, and 

 ends in it a little before its tip. Near its end, it bears a short stump of 

 a vein, which is indistinct in some specimens. The large fork formed 

 by the penultimate longitudinal vein is connected at its basis by a cross- 

 vein with the preceding vein (which is not the case in Bl. capitata). 

 An auxiliary vein is apparent, but it does not reach beyond the origin 

 of the second vein. 



There is an alula and an alar excision. In the alar excision, between 

 the alula and the anal angle, a peculiar, apparently horny knot, of irreg- 

 ular outline, is apparent, connected with a vein encompassing the alula.* 

 The fringe of hairs bordering the wing is exceedingly minute, hardly 

 visible with a lens of moderate power, except in the alar excision, where 

 the hairs are longer. The surface of the wings is bare to the naked eye, 

 but shows microscopic hairs under a magnifying power of 80-100. The 

 peculiar spider-web-like net-work existing on the wings of all the known 

 Blepharoceridce is also apparent here. 



The name of the genus is derived from the resemblance of the head, 

 with its contiguous eyes and short antennae, to that of a male Bibio. 



B. grandis, n. sp., ^ , black, opaque, clothed with blackish pile ; anten- 

 nsB black ; first joint of the flagellum somewhat paler j thorax with a 

 slight yellowish-gray bloom above, forming an indistinct design and two 

 faint stripes ; abdomen black, with indistinct markings of yellowish- 

 gray bloom ; the margins of the ventral segments and the under side of 

 the hypopygium brownish-yellow. Halteres pale yellowish-brown. 

 Feet brownish, except the coxse and the basal half of the femora, which 

 are brownish-yellow. Wings with a brownish tinge. Length, 10-11 

 millimeters 5 length of the wing, 9 millimeters. Five male specimens 

 taken in the Colorado Mountains iu August. 



Observation. — In comparing the figure of the wing of this species 

 with that of Protoplasa (Monogr. of N. A. Diptera, vol. iv, p. 317), one 

 cannot help being struck b^^ the great resemblance of both. If we pro- 

 long the interrupted vein in Bihiocephala until it reaches the cross-vein 

 above it, we obtain very nearly the venation of Protoplasa. The differ- 

 ences are (1) the undeveloped end of the auxiliary vein*of Bihiocephala 

 (which is made too weak in the wood-cut) ; (2) the absence of the super- 

 numerary longitudinal vein of Protoplasa (which vein, as I have shown, 

 loc. eit., p. 319, is but the thickei^iing of a fold existing in the same place 

 in Ptychoptera) ; (3) the absence of the cross- veins forming the discal cells. 



These differences are of far less moment than the analogies. The 

 shortness of the basal cells and the squareness of the anal angle are also 

 characteristic of both wiugs. The additional vein which distinguishes 

 Bihiocephala from the othev Blepharoceridw is the ordinary branch of the 

 second vein, apparent in Protoplasa and very common among the Tiim- 

 lidw. 



Thus, Bihiocephala serves to confirm the hint thrown out by me some 

 time ago (Monographs, &., IV, p. 3) about the relationship between the 

 Blepharoceridm and the Ptyohopterina. 



"*Mr. Burgess first called my attention to this peculiar structure, which I also perceive 

 IE Blepharocera, and which does not seem to have been noticed before. 



