LIMNOPHILINA. 191 



of the Eriopterina is far anterior to the tip of the auxiliary vein, 

 in the Limnophilina it is usually at its tip ; the Eriopterina, with 

 the exception of Gladura, have four posterior cells, the majority 

 of the Limnophilina five ; in the Eriopterina the discal cell is 

 very often open ; very rarely among the Limnophilina. Cladura 

 {Eriopterina), with its five posterior cells, is very like the Lim- 

 nophilina ; on the other hand, the Limnophilina with four 

 posterior cells are very like some Eriopterina, as for instance 

 Gnophomyia; besides the presence or absence of spurs, no im- 

 portant structural difference has been discovered yet, in order to 

 justify the present location of these forms on more than artificial 

 grounds ; nevertheless, such differences in all probability exist 

 (compare also p. 136). 



The difference between the Limnophilina and the Amalopina 

 consists in the position of the subcostal cross-vein, and in the 

 pubescence of the eyes of the latter. In both characters, Tri- 

 chocera shows an approach to the Amalopina. Another import- 

 ant difference is to be found in the structure of the penultimate 

 posterior cell. In the Amalopina this cell (compare the Tab. II, 

 fig. 14-18) is evidently formed by the fork of the posterior 

 branch of the fourth vein. In the Limnophilina this cell looks 

 in most cases as if its presence was merely due to a cross-vein, 

 separating it from the discal cell ; and indeed in the few abnormal 

 specimens that came under my observation, in which the discal 

 cell was open, it coalesced with the penultimate posterior cell, and 

 not with the cell preceding it, as it always does in the Amalopina; 

 in such specimens, the anterior branch of the fourth vein had a 

 double fork, like Dolichopeza (compare Meigen, yol. VI, Tab. 

 65, fig. 10, or Walker, Ins. Brit. Dipt. Tab. XXVIII, fig. 3 b). 

 I have not met with any Limnophilina yet, which have the discal 

 cell normally open (except the abortive form Rhicnoptila ; com- 

 pare p. 198). This peculiarity in the structure of the discal 

 cell and of the penultimate posterior cell in Limnophila de- 

 serves to be noticed, although it has been too little observed yet 

 to allow any general conclusions (compare the Introduction, 

 p. 33). 



The genera Amalopis and Pedicia have, in the majority of 

 cases, the first submarginal cell longer than the second, in conse- 

 quence of a peculiar structure of the fork of the second vein (as in 

 Tab. II, fig. 14); such is never the case among the Limnophilina. 



