13 1 



following characters only : Face less ochraceous, more gray \ third joint 

 of antennae more oval, its arista slightly pubescent, terminating in a very 

 small lamella ; the hypopygium is scarcely a third the length of that of 

 phyllophorus, though this is due in part to shrinking. 



One male specimen ; collected by Dr. Garry de N. Hough in Massa- 

 chusetts. 



Hercostomus has always been an incongruous genus, formed of 

 species rejected from several genera. The next two species differ from 

 all the genera of Dolichopodidce as now understood, but as they show 

 evident affinity to the species of Hercostomus, they may be placed, at 

 least provisionally, in that genus. The structure of the male hypo- 

 pygium, the curvature in the third vein and the presence of oral bristles 

 show a departure, more or less marked, from Gynmopterrms. The fol- 

 lowing key is wholly artificial, but readily separates the species hitherto 

 included in this much-abused genus : 



Legs largely yellow 2. 



Legs largely black 5. 



2. Post-ocular cilia black 3. 



Post-ocular cilia pale 4. 



3. Face ochraceous procerus, Wheeler. 



P'ace dark vetitus, n. sp. 



4. Antennje yellow latipes, Aldrich. 



Antennte black ivipudicus, Wheeler. 



5. Legs and lamella piceous unicolor, Loew. 



(Synonym Gymnopternus panitens^ Wheeler.) 



Legs and lamellre fuscous anari/tostus, n. sp. 



4. Hercostomus vetitus, n. sp. (Fig. r, 2.) 



Male. — Length 4.5 mm., of wing 4.5 mm. Face of moderate width, 

 brownish. Palpi piceous, proboscis fuscous, surrounded with a fringe of 

 bristles. Antennas short, black, second and third joints together rounded 

 obtusely pointed at tip, with a dorsal, short, gradually tapering, pubescent 

 arista. Vertex dark greenish. Post-ocular cilia black ; post-oral beard 

 wanting. Dorsum of thorax dark blue-green, more shining posteriorly, 

 scutellum blue-green, with surface hairy. Abdomen shining, dark blue- 

 green, becoming slightly cupreous towards apex, incisures not darkened. 

 Hypopygium large, sessile, piceous, slightly pubescent dorsally, the dorsal 

 cardiform plate bristly ; internal appendages reddish ; lamellae fuscous, 



