114 DIPTERA OP NORTH AMERICA, [PART IV. 



lateralis Macq. Eist. Natur. Dipt. II, p. 653 (syn. Limnohia 

 Jiavolimbata Hal. in Walker's Ins. Brit. Dipt. Ill, p. 304). The 

 two species which I have before me otherwise agree in their 

 venation, and differ in it from Gnophomyia : the anterior branch 

 of the second longitudinal vein is short and oblique, almost like 

 that of Goniomyia, thus modifying the shape of the first sub- 

 marginal cell (it seems, however, that in P. meigenii, which I 

 have not seen, the first submarginal cell has the same shape as in 

 Gyiophomyia) ', i\\Q petiole of this cell is longer; the marginal 

 cross-vein seems to be usually wanting. The abdomen of the 

 German species is more club-shaped at the tip than that of Gno- 

 phomyia, and the forceps has a different structure. Again, the 

 three European species agree among themselves in their coloring; 

 they have yellow stripes on the sides of the thorax and a yellow 

 scutellum, besides some other yellow marks peculiar to some of 

 them. The known American species of Gnophomyia are alto- 

 gether dark in their coloring, except the halteres of G. tristissima, 

 which are yellow. 



Psiloconopa supplies, in my opinion, the missing link between 

 the Eriopterina and the genus Goniomyia, the link for which I 

 have been looking unsuccessfully in the Proc. Acad. Nat. Sci. 

 Philad. 1859, p. 230. This has become particularly evident to 

 me, since I have seen Psiloconopa lateralis Macq., the venation 

 of which (short first submarginal cell, oblique anterior branch of 

 the second vein, open discal cell, coalescent with the third 

 posterior cell) very forcibly reminds of Goniomyia. The preva- 

 lence of yellow in the coloring of Psiloconopa increases the 

 probability of the relationship of these two genera. My know- 

 ledge of Psiloconopa is not sufficient to enable me to decide 

 upon the degree of this relationship ; but at the same time, I 

 have seen enough of this genus to convince me that it would be 

 premature to unite it with Gnophomyia. 



Description of the species. 



1. G. llictuosa 0. S. % . — Atra, halteribus atris ; alls obscure in- 

 fumatis. 



Black, opaque ; halteres black ; wings smoky blackish. Long. corp. 0.32. 



Syn. Gnophomyia luctuosa 0. Sacken, Proc. Ac. Nat. Sc. Phil. 1859, p. 224. 

 Limnobta nigricola Walker, Trans. Ent. Soc. Lond. V, n. s. part VII, 

 p. 66. 



