MICROPEZID^ TANYPEZIM. 265 



nying figures (9, 1O) . A second genus, Tetr^adiscus 

 Bigot, may possibly belong here, though it has the first 

 posterior cell open and the third joint of the antennae 

 rounded. The genus, if not identical with some other 

 already known, can not be located until specimens are 

 studied by some competent dipterist. 



Micropezidcz . Head subsperical; front rather broad, 

 not bristly on the lower part. Kyes relatively small, the 

 orbits and cheeks moderately broad. No oral vibrissae; 

 face retreating in profile, sometimes very much so. Tho- 

 rax narrowed anteriorly. Antennae short or moderately 

 elongated, porrect. Abdomen elongate; male genitalia 

 often large and complicated. Wings elongated; auxil- 

 iary distinct in its whole course; or so closely applied to 

 the short first longitudinal vein as to be distinguishable 

 with difficulty. Anal cell always present, short, or drawn 

 out into an acute point; second basal cell sometimes con- 

 fluent with the discal cell; first posterior cell closed or 

 much narrowed in the margin. Legs long and slender, 

 the tarsi shorter than the tibiae; no preapical tibial 

 bristle. 



So far as the known European and North American 

 genera are concerned, the above diagnosis clearly defines 

 the limits of the group. There are numerous forms in 

 South America, however, which seem to break down the 

 limits on the one hand from the Piophilidae, on the other 

 from the'Ortalididse. The narrowing or closure of the 

 first posterior cell is very distinctive of our species, but 

 is net a group character. Nor are the slender legs a real 

 'family' character, since there are southern forms with 

 thickened hind femora and shorter legs which insensibly 

 connect the more typical Calobattz or Micropeza, through 

 Cardiacephala, with the Ortalididae. The group is dis- 

 tinctively a South American one. The writer has more 

 than a score of species in his collection from Brazil. 



