TAXONOMY OF MUSCOIDEAN FLIES — TOWNSEND 69 



between small crossvein and bend of fourth vein, stump of fifth vein 

 extends to wing border; first and second antennal joints and base of 

 third reddish yellow, arista and rest of third antennal joint black or 

 brownish; thjrd antennal joint rounded on posterior apical corner, 

 subangular on anterior apical corner. Palpi brownish yellow, or 

 with a reddish tinge. Front fully one-half width of head, frontalia 

 brownish yellow ; face and front silvery white, parafrontals slightly 

 cinereous. Thorax, scutellum, and pleurse quite thickly silvery 

 pruinose over the black ground color. Abdomen obscure light 

 brownish red, obscurely blackish on median line, broadening on hind 

 portions of second and third segments and nearly covering fourth 

 segment ; anterior borders of second to fourth segments broadly 

 silver}- pruinose, but more faintly so than thorax; legs blackish; 

 wings clear, slightly tawny at base. Teguke white, very slightly 

 tinged with yellowish. 



Type.— Cat. No. 10,901, U. S. N. M. 



PHOSOCEPHALA, gen. nov. 1 



Form rather L?/r/7/a-like, narrow, abdomen round-oval, head yel- 

 low, wings slightly smoky, palpi absent, thorax and abdomen me- 

 tallic. 



Head and thorax about same width, abdomen slightly wider. 

 Front (female) not prominent in profile, distinctly more than one- 

 half width of head, flattened anteriorly, steeply sloping on anterior 

 two-thirds, ocelli marking summit, vertex lower; parafrontals wide, 

 not swollen, clothed with some fine black hairs ; vertex not nar- 

 rowed ; frontal bristles descending in a single row about to middle 

 of second antennal joint, the four front pairs decussate and widely 

 divergent below ; two strong reclinate frontal bristles next behind 

 these and between them a pair of weak bristles also directed back- 

 ward, the outer one outward ; two reclinate vertical bristles of equal 

 strength on each side, the outer one directed also outward, these 



1 This genus and several others were purposely described in detail in order to 

 furnish a forcible illustration of the length of a full generic description in 

 these flies, mentioning all the characters, such as would be necessary to enable 

 the student to absolutely place the form in its proper tribe or subfamily with- 

 out reference to the specimen. Such a description is far too long for practical 

 use, and demonstrates the inadvisability of attempting systematic work in tins 

 superfamily without a great amount of previous study and access to a large 

 central collection where all types are to be permanently preserved. Especial 

 attention is here called to the fact that all these characters require to be 

 studied and compared in order to determine the final location of a genus of 

 these flies. 



