118 DIPTERA OF NORTH AMERICA. [PART II. 



originally gray. Cilia of the inferior orbit, as far as I can dis- 

 tinguish, black. Scutellum without hairs. Hypopygium black ; 

 its lamella? rather large, oval, narrowed at the root, fringed with 

 black hairs ; they have a blackish appearance, are however really 

 black only on the margin, while in the middle, at least when seen 

 in a certain direction, they look dingy whitish. Coxa? and feet 

 black, the latter plain ; femora with a greenish reflection ; the 

 upper side of the fore tibia? only with two small bristles. The 

 yellowish-white tegulse have black cilia. Wings grayish hyaline 

 with rather delicate black veins ; they are comparatively long and 

 narrow and have a very regular elongated elliptic outline. The 

 last segment of the fourth longitudinal vein is especially long, 

 with an imperceptible sweep and approaches in its entire course 

 gradually the third longitudinal vein, so that their ends are not 

 very distant from each other. 



Rob. Fort Resolution, Hudson's Bay Territory. (Kennicott.) 



Gen. X. HYPOPHYLLUS. 



This genus may be characterized in the following manner : The 

 first joint of the antenna? distinctly hairy on its upper edge, the 

 second joint of the antenna? transverse, the third not elongated ; 

 the arista dorsal, very bare, rather strong as far as its end ; its 

 first joint in the male remarkable either for its great length or its 

 incrassated tip. The face of the male very narrow, especially 

 below ; the face of the female broader, sometimes much broader. 

 Scutellum not hairy. Abdomen elongated, that of the male 

 rather strikingly pointed at the end. The entirely disengaged 

 hypopygium pedunculated, usually of a yellow color ; its exterior 

 appendages lie on its under side, stretched out alongside of each 

 other, and are small, narrow, elongated lamellae ; the interior ap- 

 pendages are remarkable for their extraordinary development, are 

 much longer than the exterior ones, either strap-shaped or broader 

 at the end and beset with long hairs. Feet comparatively long 

 and slender ; the first joint of the hind tarsi without bristles and 

 shorter than the second. The last segment of the fourth longi- 

 tudinal vein has only a very gentle sweep and very gradually ap- 

 proaches the third longitudinal vein. 



The narrow, stretched-out shape of the body, the peculiar struc- 

 ture of the arista, the long pedunculated yellow hypopygium and 



