DIPTEROUS TRIBE SPH.EROCERIDiE. 317 



A very small proportion of the species described by conti- 

 nental authors have yet been found in Britain. The diligent 

 researches of Mr. F. Walker have added several well-marked 

 species to our Fauna, and he most kindly transmitted the entire 

 of his rich collection for my use. Even with these accessions 

 the list is scanty, but I have convinced myself that many of 

 their characters are subject to vary so much as to render great 

 caution expedient in separating species. I have therefore 

 omitted several, which may prove distinct, from not having a 

 satisfactory series of examples. There is so much uniformity 

 of colour among these insects, that we must generally depend 

 on less obvious distinctions. I have found the disposition of 

 the nerves in the wings sufficiently constant to be of service in 

 this respect. 



Fam. — Musclar. 

 Tribe. — Spu^ROCERiDiE. 



Calyptra fere nulla. Nervus longitudinalis l us . simplex, vix \ 

 costce pertingens : tarsorum posticorum articulus l us „ 

 dilatatus, 2 d0 . brevior : antennarum articulus 3 US . sphceroi- 

 deus, arista dorsali elongata gracillima. 



Synonyma. — Borborus, Meigen. Sphaerocera, Latr. 



Copromyza spp. Fallen. Nerea, Bacchis, Mycetia, 



Sphaerocera, Lordatia, Coprina, Fimetia, Scatophora, Olina, 

 Rob. Desvoidy. Spaeroceridae, Macquart. 



Front broad, subquadrate, a little inclined : orbits, frontals, and 

 stemmatie triangle usually distinguished : ocelli three : eyes 

 round: antennas rather distant, short, slightly deflected : 1st joint 

 very small : 2d as long as 3d ; 3d transversely spheroidal, 

 obliquely compressed : arista dorsal, long and slender, with only 

 two joints apparent : face broad, impressed, membranaceous : 

 epistoma prominent, bearing vibrissas at the corners : clypeus 

 exerted transverse : cavity of the mouth very large, rounded : 

 labium thick, fleshy ; below with a broad bellying sheath of horny 

 consistence, and hairy : labella round, obliquely striate : labrum 

 short : tongue obsolete : maxillae with a small linear and hairy 

 lobe disengaged from the lip : palpi linear, bristly : thorax rather 

 depressed : abdomen depressed, oblong, often showing only six 

 segments in the male, as the penultimate is withdrawn ; and but 

 five in the female, the remainder being very small, tubular, 

 and internal ; sometimes falling short even of that number, from 



