GNOPHOMYIA. 173 



of the two North American species will be given below in the 

 description of these species). The horny appendages of the for- 

 ceps of G. tristissima are remarkably slender, almost linear and 

 pointed ; the corresponding appendages of G. luctuosa seem to 

 be shorter. The ovipositor of the female (G. tristissima) has the 

 upper valves of moderate length and breadth (Tab. IV, fig. 19, 

 a) ; incrassated and arcuated on the under side at the basis, 

 which gives a peculiar appearance to their manner of attachment; 

 the lower valves' are very short, reaching but little beyond the 

 basis of the upper pair. 



Closely allied as Gnophomyia is to Trimicra and Symplecta, 

 it may at once be distinguished by the position of the subcostal 

 cross-vein, which is much nearer to the tip of the auxiliary vein 

 than is the case in those genera ; by the position of the great 

 cross-vein, which is not anterior to the inner end of the discal 

 cell; by the structure of the forceps of the male, etc. Both 

 North American species are altogether black ; the knob of "the 

 halteres of one of them only is yellow. I have seen two South 

 American Gnophomyise in the Berlin Museum, one of which is 

 the Limnobia nigrina Wied. Auss. Zw. II, p. 37. A handsome 

 species from the Cape, with brown wings, banded with white (in 

 the same museum), is either a Gnophomyia, or closely related to 

 this genus. 



The genus Gnophomyia (from yv6$o$, darkness, and fivia, fly) 

 was introduced by me in the Proc. Acad. Nat. Sci. Philad. 1859, 

 p. 223. The genus, described under this name in the Fauna 

 Austriacais Trimicra (comp. above, page 167). 



A genus closely allied to the present one is Psiloconopa (from 

 4-a6s, glabrous, and xava^, gnat). It was established by Zetter- 

 stedt, in 1840 (Fauna Lapponica, p. 847, and later Lipt. Scand. 

 X, p. 4007), upon a single species (P. meigenii), found in the 

 northern parts of Sweden. The genus has hardly been noticed 

 since, although several other species occur in Europe. The 

 typical species, P. meigenii, I have not seen, but have before me 

 an apparently undescribed species from Germany, larger than P. 

 meigenii, and distinguished by the frequent absence of the mar- 

 ginal cross-vein. Of another, smaller species, I have a single 

 specimen from the north of Italy. It has no marginal cross-vein 

 and its discal cell is open, coalescing with the third posterior 

 cell. There is but little doubt that this species is the Erioptera 



