118 Annals Entomological Society of America [Vol. XV, 



Australian forms even the upper branch of the cubital fork may- 

 be variable, being present in some specimens of one species 

 and wanting in others. I have never found this to be the case 

 with South American forms, which all have an unforked cubital 

 vein, except in Hylorus. I have observed the following 

 anomalies : 



(a) The hind cross-vein may be more or less obliterated, in part or as a whole, 

 the discoidal cell being thus partly or entirely open. 



{b) The third vein issuing from the discoidal cell may be quite wanting or 

 represented by a short stump. 



(c) The ambient vein may be sometimes rather indistinct, chiefly in female 

 specimens. 



It is evident that this variation by reduction refers chiefly if 

 not exclusively to the veins of the hind half of the wings. It 

 may be interpreted as a condition of the true Stratiomyiid flies, 

 in which the veins of the fore half only are thickened and 

 crowded together near the costa, and as a tendency toward 

 degeneration of wing, a fact which has reached its climax in 

 the Australian genus Boreoides with subapterous females. 



The South American genera of the tribe may be distinguished 

 as follows: 



1. (2) Third longitudinal vein forked; eyes bare and united in the male; third 



antennal joint with numerous annulations Hylorus Phil. 



2. (1) Third longitudinal vein simple; third antennal joint with less than 



8 annulations. 



3. (6) Eyes of male united, quite bare or with few and scattered hairs; third 



antennal joint more or less distinctly annulated or even simple. 



4. (5) First antennal joint much longer than the second, being as long as the 



third Inopus Walk. 



5. (4) First antennal joint as long as the second and much shorter than the third; 



metapleura with short hairs; wings with microscopical pubescence and with 

 the first longitudinal vein clothed with short hairs Chiromyza Wied. 



6. (3) Eyes of male broadly separated, and clothed with abundant and short 



hairs; third antennal joint with deep annulation, and much longer than the 

 first; metapleura with long hairs; wings with long pubescence and with the 

 first longitudinal vein clothed with long hairs Barbiellinia, n. genus 



I. Hylorus Philippi. 



The unique South American form with forked third longitudinal 

 vein, only known by the type species Krausei Phil, from Chile. Placed 

 in Chiromyza by Hardy; not seen by the writer. 



II. Inopus Walker. 



The unique South American form with elongated first antennal 

 joint, only known by the type species despectiis Walker from South 

 America. Placed by Mr. Hardy with a query in synonomy with the 

 Australian Metoponia rubriceps Macq. ; not seen. 



