HYDKELLIA. ' 255 



unguiculate. Every facet of the eyes appears to produce a short erect 

 hair from its centre, Avhich gives a velvety pile to the whole, and an 

 indefinite outline when viewed by a magnifier, unless in the direction 

 of a row of the lenses. 



SYNOPSIS OF THE SUBGENEKA. 



^convex 1. Hydeellia. 



^ pectinated above. Face < 

 4 . , N (.impressed 2. Atissa. 



Cvery minutely pubescent 3. Glenanthe. 



Subgenus 1. Hydrellia. 



Hydrellia, Desv. ; Hal. A. N. li. iii. 401 (1839). 



Fades convexa, superne attenuata, squamuloso-mica^is, puncto lucido nn- 

 temiaruni basin superante. Palpi subddatati. Antenna; articulo tertio 

 ovato aid orbiculato, conipresso, defiexo ; arista dorso pectinata. Alee 

 apice rotundatce. Vena discali-recurrens ab alee margine parum dis- 

 tans. 



Face convex, attenuated above, sJdning, as if sqnamulose, with a lucid 

 spot above the base of the antennae. Palpi slightly dilated. Antennce 

 with the third joint oval or orbiculate, compressed, deflexed ; arista pec- 

 tinated above. TFings roimded at the tips. Discal-recurrent vein near 

 the border of the wing. 



The species of this group generally occur in great profusion in 

 their favourite localities^ and are subject to some variation in the 

 colour of the face, antennte, and mouth. The general colour of 

 the body is rather uniform, ranging from a dull olive or cinereous 

 shade to a shining black. The halteres are sulphureous, with the 

 base black in the dark-coloured species, brown or tawny in the 

 others. 



1. Cardamines, Hal. A. N. H. iii. 402. 1 (1839). Nigro-cenescens, 

 antemds subtus facie ore palpis coxis et tibiis anticis totis tibiis poster io- 

 ribus apice tarsisque basi fulvis. Var. /3. Facie albo-micante. Var. y. 

 Antennis et mento nigris. Long, f-li lin. 



JEneous-blach . Antenna beneath, face, moxdh, palpi, cox(e,fore tibia, 

 hinder tibia at the tips, and tarsi at the base taxony. Var. /3. Face with 

 white reflections. Var. y. Antennee and mentum black. 



Among aquatic plants, at Hollywood, near Belfast ; local, but 

 not rare. (I.) 



2. flaviceps, Meig. Zw. vi. 72 (1830) ; Mcq. ; Hal. — aurifacies, 

 Desv. Obscure viridis, ore palpisque flavis, facie f lava albo-micante, an- 

 tennarum articulo tertio tibiis tarsisque fulvis, tibiis posticis annulofusco. 

 Lonff. 1 ; alar. 2 lin. 



