DIPTEROUS TRIBE OF SPH^ROCERID.E. 333 



fewer bristles ; 2d joint of hind feet shorter : wings blackish : 

 base of the costal nerve less bristly, 2d ending half way between 

 the 1st and 3d ; cross nerves not so distant. (Length 4 : wines 

 n line.) 



Common in the same situations with No. 6. 



AA. AntenncB in latera aversce. 



B. Oculi nudi. 



C. Areola marginalis costam mediam superans. 



Sp. 19. L. zosterse. Nigra opaca alts infiimatis. 

 Borborus zosterae, Ejit. Mag. I. 178. 



Opaque black : front gibbous, bristly : face much elevated between 

 the antennae, which are turned in opposite directions, lying close 

 to the eyes ; their 2d joint is very bristly, and larger than the 3d : 

 the arista thickly pubescent, the pubescence whitish : thorax 

 scarcely pubescent, very flat, with an impressed line down the 

 middle : scutel not as long as the metathorax ; glabrous, with 

 four bristles, as also in those which follow : legs rather short, 

 thinly hairy, piceous, with the knees and feet tawny, or entirely 

 tawny : middle shanks armed with numerous bristles : 2d joint of 

 hind feet not very long, scarcely thickened : poisers with a deep 

 brown knob : wings of a brownish yellow, the nerves of the same 

 colour ; costal more dusky, rather thick, bristly at the base ; 2d 

 nerve extending little more than half way between the 1 st and 3d : 

 intervals of the cross nerves considerably longer than the principal 

 one. (Length l\ ; wings 3 lines.) 



There is a variety scarcely a third that size, but differing so little in 

 other respects, that I cannot consider it a distinct species. 



Common on sea-weed : Mr. Walker has found it near 

 London ; and also in the Isle of Wight, Cornwall, and North 

 Wales. 



Sp. 20. L. leucoptera. Nigro-fusca, alts albis, costa nigri- 

 cante. 



Dusky with paler legs : eyes small : arista with thick whitish 

 pubescence : scutel short, nearly semicircular : middle shanks 

 bristly ; 2d joint of hind feet long and scarcely thickened : poisers 

 brown : wings whitish ; the costal nerve and those next to it 

 dusky, the rest colourless ; the costal region dusky towards the 

 end : costal nerve with a few bristles at the base, a little thickened 

 from the 1st to the 2d main nerve; the latter ending much 

 nearer to the 3d ; marginal cell long and very narrow ; sub- 



