SYSTEMATIC ACCOUNT. 49 



nocephala, Hypselothyrea, Liomyza, Sigaloessa, and Uranucha because it 

 seems to me that they can conveniently be placed in a group of their 

 own. Specimens of Periscelis that I have seen seem to fit best in the 

 Agromyzinse. The types of Stenomicra appear to me to be Geomy- 

 zinse. Curtonotum and Aulacigaster I have included in the Droso- 

 philinse because they do not fit well anywhere else, and it is now 

 customary to put them here. It remains very doubtful whether they 

 are really any closer to Drosophila, Stegana, etc., than are some of the 

 Geomyzinse (e. g., Diastata, Mumetopia) or Milichiinse. 



In general, a small acalypterate fly with plumose arista, convergent 

 postverticals, twice-broken costa, rudimentary auxiliary vein, anal cell, 

 and vibrissse present, is a drosophiline. Any specimen with all these 

 characters may safely be referred here; but every one of these pecul- 

 iarities is lacking in some member of the group. The postverticals are 

 always convergent if present; but some forms have no postverticals 

 at all. The costa is always at least weakened a second time; but the 

 humeral weakening is in some cases not an actual break. Vibrissae 

 are present in all North American forms, but absent in the exotic 

 genera Idiomyia and Apsinota. The anal cell is very often incomplete. 

 The auxiliary vein is well developed in Curtonotum, Apsinota, and 

 Aulacigaster. The arista is pubescent in several genera, pectinate in 

 Titanochwta, and has a single branch in Cladochata. 



The following subfamilies are the ones most likely to be confused 

 with the Drosophilinae : Lauxaniinse, Milichiinse, Agromyzinse, Ephy- 

 drinse, Geomyzinse, Chloropinse, and Asteinse. These may usually be 

 distinguished by the following means, though with a little practise one 

 will come to rely fully as much on the general appearance of the speci- 

 men, without examining the minute characters, except in rare cases. 



Lauxaniince: Auxiliary vein distinct throughout its course; two orbital bristles. 



Milichiince: Arista never plumose; auxiliary vein usually ending in the costa; discal and 

 second basal cells separated; clypeus small; lower orbital bristles convergent. 



Agromyzince: Costa once broken; postverticals divergent. 



Ephydrince: Anal cell and anal vein absent; face convex or flat. 



Geomyzinoe: Costa once broken; auxiliary vein usually ending in costa; arista seldom 

 plumose. 



Chloropiyice: Costa once broken; anal cell and vein absent; vibrissse absent; arista rarely 

 plumose. 



Asteinos: Anal cfeU absent; arista usually not plumose; costa not broken at humeral cross- 

 vein. 



GENERA OF DROSOPHILIN/E. 



The following will serve to characterize the 22 genera here recog- 

 nized as belonging to the Drosophilinse. I have examined specimens 

 of 17 of them. 



1. Auxiliary vein distinct for most or all of its length 2 



Auxiliary rudimentary or ending in first vein near its base , 4 



2. Arista plumose; prescutellars large; mesonotum strongly convex 3 



Arista minutely pubescent; no prescutellars or postverticals; mesonotum not 



strongly convex A ulacigaster 



