DICRANOMYIA. 55 



The submargiual cell is always a good deal longer iLan the first 

 posterior cell ; the relative proportion of their length is subject 

 to slight variations. When the discal cell is open, which charac- 

 terizes several species, it coalesces with the second posterior cell, 

 in consequence of the absence of the cross-vein, connecting the 

 two first veins emitted by it towards the margin of the wing. U. 

 pubipennis (Tab. I, fig. 2) is the only exception I know of, to 

 this rule ; whenever in this species the discal cell happens to be 

 open, it coalesces with the thu^d posterior cell, because it is the 

 cross-vein connecting the two last veins, emitted by the discal 

 cell, which is wanting. As a rule, the discal cell is open in D. 

 immodesta, gladiator, rdstrife7'a, fioridana, longipennis, hrevi- 

 vena ; it is closed in D. diversa, pudica, halterala, distans, siultu, 

 hserelica, liberia, defuncta, rara, humidicola, morioides. Among 

 twenty specimens of D. piuhipennis five had the discal cell open; 

 of my two specimens of D. glohithorax one has this cell open, the 

 other closed. But even in the species which have the discal cell 

 either open or closed as a rule, occasional exceptions occur ; this 

 character is therefore not an altogether reliable one, and can be 

 established only upon the comparison of a number of specimens. 

 The shape of the discal cell is more or less square ; its inner end 

 is either in a line with the small cross-vein, or somewhat arcuated 

 and projecting on the inside beyond this cross-vein. The position 

 of the great cross-vein is generally in a line with the inner end 

 of the discal cell; sometimes a little anterior or posterior to this 

 line ; it varies in difi"erent specimens of the same species. 



The male forceps consists of a pair of movable, fleshy lobes, 

 oblong, often subreniform, each being armed on the inside with a 

 short, curved horny appendage, somewhat resembling a beak (I 

 call it rostriform appendage) ; it often bears upon its convex 

 side one or two stiff bristles (see Tab. Ill, fig. 3 and 5, d). To 

 the upper side of each of the lobes, another horny appendage, 

 long, slender, attenuated, curved, is closely applied {falciform 

 appendage) ; its point of attachment is the basal piece below 

 (fig. 5 and 3, b). The forceps of D. humidicola (fig. 2) and that 

 of D. liberta (fig. 3), with their full, rounded lobes may be con- 

 sidered as typical. Often, these lobes are more slender, sinuated 

 or excised on the inside, such are for instance, those of D. de- 

 functa (fig. 1) ; or somewhat club-shaped towards the tip, as in 

 D. hasretwa. Below these lobes, at the end of the body, on the 



