SMTLIOTUS. 



venter whitish. The small hypopygium black ; the exterior ap- 

 pendages are of a dusky gray-yellowish color, comparatively long, 

 fork-shaped and split into a shorter and a much longer internal 

 lobe ; the hornlike interior appendages are black and pointed. 

 The yellowish fore coxa? are upon their whole basal half of a 

 brownish-black color, and fringed on the front side with long 

 whitish hairs. There are no black bristles upon them. Middle 

 coxa3 blackish with yellowish tip, the latter with a considerable 

 black thorn, which seems to be composed of several contiguous 

 bristles. Hind coxae of the same color as the middle coxa3. Feet 

 yellow ; hind femora almost upon the whole apical half black ; 

 hind tibiae although strong, but not incrassated, their last third 

 black. Fore and middle tarsi somewhat infuscated, their end and 

 the tip of their first joint more dark brown ; the first joint of the 

 fore tarsi of the usual form, the hind tarsi black. Cilia of the pale- 

 yellowish tegula3 whitish. Wings tinged with gray, a little darker 

 upon the last part of their anterior margin ; the last segment of 

 the fourth longitudinal vein gently inflected forward upon its 

 middle. 



Hob. District Columbia. (Osten-Sacken.) 



Gen. XXI. S1HILIOTIJS. 



Characters. Face in both sexes broad. Palpi large, concealing 

 the proboscis. The antennae in both sexes of a similar structure ; 

 the first joint on the upper side without hair ; the second of the 

 usual transverse form ; the third joint of different length in dif- 

 ferent species, on the under side nearly excised from the root to 

 the tip ; the arista entirely apical, the first joint short and stout, 

 the second, however, long, very slender, particularly towards the 

 tip. Scutellum without hair. The abdomen of the male shows 

 only five segments, while there are six in the related genera. 

 The small rounded hypopygium is imbedded and has only very 

 short appendages. All the tarsi are short, especially the hind 

 tarsi, the first joint of which has no bristles ; the pulvilli of the' 

 fore tarsi of the male are enlarged. The wings are elongated, of 

 rather equal breadth, and have a distinctly protruding anal angle ; 

 the last segment of the fourth longitudinal vein is somewhat in- 

 flected, ends beyond the tip of the wing and runs upon its middle 

 over a large but flat impression. 



