OPOMYZIDAE — SEPSIDAE. 43 



Fam. XLIX. OPOMYZIDAE. 



Charact. — Front with stout bristles above ; clypeus rudimentary ; border 

 of the mouth either pubescent or with long hairs, the foremost of 

 which sometimes forms a distinct vibrissa. Proboscis short ; palpi 

 rather small. Middle tibiae with a distinct, posterior tibise with a 

 very short spur ; the exterior side of the tibia? without erect small 

 bristle before the tip ; claws and pulvilli small. Wings elongated 

 and narrow, with no bristles at the costa; the axillary incision and 

 alula? are either wanting or very diminutive. First longitudinal 

 vein much abbreviated ; the auxiliary vein becomes obsolete before 

 reaching completely the first longitudinal vein ; the latter emits, 

 shortly before its end, towards the costa, a branch, which may be 

 considered as the eud of the auxiliary vein ; basal cells small. 



No species belonging to this family has as yet been noticed in 

 N. A. 



Fam. L. SEPSIDAE. 



Charact. — Head rounded ; front bristly; border of the mouth more or less 

 hairy, the foremost hair often imitating a vibrissa ; clypeus rudi- 

 mentary ; proboscis short ; palpi exceedingly small or wanting. 

 Abdomen tapering towards the base. Middle tibise with distinct 

 spurs ; claws aud pulvilli small. Neuration of the wings complete; 

 the auxiliary vein distinctly separated from the first longitudinal 

 vein ; the two posterior basal cells rather large. 



The most essential character of this family is the rudimentary 

 condition of the palpi. With this exception its characters are 

 rather similar to those of the Micropezidce. The genus Cephalia 

 approaches very much the Sepsidce in structure, but its incrassated 

 proboscis, its large and broad palpi, and its considerably developed 

 clypeus prevent it from being reunited with them ; it must, there- 

 fore, remain among the Ortalidce. 



The species of Sepsidce occurring in N. A. belong to the genera 

 Nemopoda and Sepsis, and are, in part, identical with European 

 species. 



