OCHTHERA. 249 



group, unless it be with certain species of the Geomijzlda, which 

 appear to offer the nearest affinity. Nevertheless from these tlie 

 HijdromyzidcB may be distinguished either by the form of the head 

 and mouth, the characteristic imperfection of the areolets of the 

 wing, or the total concealment of the ovipositor. The greater 

 number frequent the neighbourhood of waters, a destination indi- 

 cated by the satiny lustre of the minute scales which clothe the 

 face and sides. Ephjdra riparia, the feet of which are formed 

 peculiarly for resting on the surface of pools, is liere regarded as 

 the type of the group. The larvse of most Ephydra live among 

 the semi-fluid green matter which mantles on the surface of stag- 

 nant waters, or in the mud at the bottom. Desvoidy assumes 

 that the other genera of the tribe, in their larva state, are nourished 

 by the living tissue of phanerogamous plants ; but this view rests 

 on conjecture, and a solitary fact observed regarding a species of 

 Notij)Mla. The form and homogeneous texture of the face in- 

 dicates but little sensibihty to smells, from whence we may pro- 

 bably conclude that the larvae are not eminently saprophagous." — 

 Halidai/. 



SYNOPSIS OF THE GENERA. 



/■oval, incrassated 1. Ochthera. 



Fore femora < ,■ 3 ^ ^^ o xr 



] /^densely pilose 3. Hydrellia. 



(.like the pes- N 



terior. Eyes ^ bare, or with scattered ^unguiculate 2. Notiphila. 



C hairs. Second joiut j 



of the antennae . (. not ungui- 



culate . 4. Ephydea. 



Genus I. OCHTHERA. 



Ochthera, Lair. H. N. xiv. 321 (1814 ?) ; Fal.; Meig. ; Mcq. ; Desv.; 

 Hal. ; Zett. Musca p., D. G. ; F. Tephritis p., F. 



Corpus vix nisi nudum. Caput subtus attenuatum, subtrigonum. 



Vertex impressus. Clypeus exsertus, suborbiculatus. OcuU magni, 



protuberantes. Palpi e.xscrti, dilatati. Arista dorse ciliis perpaucis 



pectiiiata. Vena discali-recurrens obliquata. Areola prima exterior 



apice attenuata. Abdomen deplanatum. Pedes antici femoribns 



crassis ovatis, tibiis arcuaiis acutis. Metatarsus posticus iucrnssatus. 



Body almost bare. Head nearly triangular, attenuated beneath. 



Vertex impressed. Clypeus projecting, suborbiculate. Eyes large, 



prominent. Palpi exserted, dilated. Arista with very few bristles 



above. Discal-recurreut vein oblique. First exterior areolet attenuated 



VOL. II. 2 K 



