108 [April, 1901. 



One supra-alar bristle situated immediately over the root of the wing and on 

 the edge of the sutural depression. 



Two pontalar bristles on the postalar callus. 



Usually five pairs of outer dorso-central bristles, one pair being in front of the 

 thoracic suture, thougli in H. oculata there are only three pairs strongly developed. 



Of the inner dorso-central bristles only a prsescutellar, and sometimes one 

 other, pair are present. 



Four scutellar bristles (two pairs). 



Pleuha. — One strong prothoracic bristle over tlie front coxae. 



One strong sternopleural bristle at the hind top corner of the sternopleursi. 



The nearest allies of Ueteromyza are BIej)liaroptera on the one 

 hand, and Tepliroclilamys on the other, from either of which it can be 

 easily distinguished by the characters given in italics in my definition 

 of the genus. Blepharoptera has decided spines on the costa, and 

 only four pairs of dorso-central bristles on the thorax, while Te- 

 phroclilomys, though having an almost bare costa. has only three pairs 

 of dorso-central bristles ; and in both genera the stigma is not 

 elongated, the first longitudinal (subcostal) vein not being continued 

 beyond that point of the costa o])posite the middle (discal) cross 

 vein, but ending in the costa at, or before, that point. Its chtetotaxy 

 will distinguish it from any Anthonn/idous genus which it may super- 

 ficially resemble. 



The genus was first introduced into our British List by, I believe, 

 Curtis in his Guide, but it is very doubtful if the species there re- 

 corded were correctly identified. 



The three species may be tabulated as follow^s : — 



1 (4) Five pairs of outer dorso-central bristles on the thorax. Antennae entirely 



black. Fronto-orbital bristles present in both sexes. 



2 (3) Male. — Frons with a greyish-white vertex and side lines, and much wider 



than in the ner.: species ; face very narrow, much narrower than the frons. 

 Female. — Face distinctly narrower than the frons 1. atricornis, Mg. 



3 (2) Male. — Frons all dull red and rather narrow, being about three times as wide 



at the vertex as the posterior ocelli are apart, but slightly less above the 

 antennae ; face wider than the frons. Wings darkened. Female. — Face 

 not narrower than the frons 2. rotundicornis, Ztt. 



4 (1) Only three pairs of outer dorso-central bristles strongly developed on the 



thorax. Antennae more or less reddish-brown ; eyes of the male very 

 nnich approximated at the vertex, and in that sex the frons is much wider 

 just above the antennae than at the vertex and without fronto-orbital 

 bristles 3. oculata. Fin. 



1. — H. ATRicoKNis, Meigen. 

 S . Eyes lai'ger, frons wider, and face narrower than in either of the other 



