GONIOMYIA. ITT 



wanting in all the species to me known ; the relative length of the 

 second submarginal and of the first posterior cells is somewhat 

 variable; they are of equal length in G. sulphurella ; the sub- 

 marginal is a trifle longer in G. cognatella and subcinerea ; a 

 good deal longer in G. blanda ; the discai cell is open in some 

 species and closed in others ; this character is in some measure 

 even variable within the same species, and therefore not entirely 

 reliable ; whenever the discai cell is open, it coalesces with the 

 third posterior cell, 1 and thus it becomes apparent that it is the 

 anterior branch of the fourth longitudinal vein which is forked ; 

 fifth, sixth, and seventh veins nearly straight ; the latter some- 

 times slightly curved before the tip. The veins almost glabrous, 

 except in some rare cases, when they show a more distinct, 

 although very short pubescence. 



These delicate insects are distinguished by the frequent occur- 

 rence of a peculiar sulphur yellow in their coloring, and in this 

 respect the European and the American species agree with each 

 other. They are not numerous — four or five being known in 

 Europe, and four having been discovered in America. The 

 peculiar shape of the first submarginal cell distinguishes them 

 easily ; and if we add to that the relative position of the tip of the 

 auxiliary vein to the origin of the second vein (so different from 

 the other Eriopterina), the absence of the marginal cross-vein 

 (at least in all the species known to me) ; the coalescence of the 

 discai cell with the third posterior cell, whenever it is open ; and 

 the peculiar structure of the male forceps, visible even in dry 

 specimens, we will have sufficiently characterized the genus. 

 The majority of the European species have the forceps of an 

 analogous structure ; one or two of them seem to be different ; 

 I have not seen the species of the latter kind and have therefore 

 no opinion about them. 



In speaking of the genus Psiloconopa (compare above, p. 1T4) 

 I have alluded to the possible relationship between it and Gonio- 

 onyia, especially apparent in the European P. lateralis Macq. ; 

 this discovery seems to resolve the doubts which I formerly enter- ' 

 tained (Proc. Acad. Nat. Sci. Philad. 1859, p. 230) about the 

 location of Goniomyia among the Eriopterina. 



1 Exceptions are merely individual ; thus I Lave seen a specimen of G. 

 subcinerea, the discai cell of which was coalescent with the second posterior 

 cell. 



12 Sept., 1868. 



