200 DIPTERA OF NORTH AMERICA. [PART IV. 



type of the geuus Limnophila. I have not had an opportunity to 

 examine the forceps of the European species. 



T. Poecilostola, a genus adopted by Dr. Schiner (1. c. II, p. 

 551) for four European species of large size and with spotted 

 wings. No American species, belonging here, arc known as yet; 

 and I have not had sufficient opportunity to study the European 

 species. P. jnctipennis reminds of Limnophila luteij)ennis in 

 the structure of its head and thorax ; P. iDunclata is quite differ- 

 ent in this respect, and P. barbipes still more so. The above- 

 quoted species, it seems to me, show a leaning towards Priono- 

 labis on one side, and to the group of which L. luteipennis 0. S. 

 is the type on the other. Like the latter group, the species of 

 Poecilostola have the pits on the humeral part of the mcsonotum 

 very distinct, and also the corresponding blackish double dots on 

 the front part of the intermediate stripe of the thorax. 



8. Limnophila luteipennis 0. S., L. confempta, n. sp., and L. 

 inorna/a, n. sp., form a natural group, distinguished by the struc- 

 ture of the head, narrowed behind ; a neck-like prolongation of 

 the collare ; the venation (length of the second submarginal cell, 

 arcuated course of the posterior branch of the second vein, in- 

 curved tip of the seventh vein, etc , compare Tab. II, fig. 10, the 

 wing of L. luteipennis) ; the structure of the antennae, the joints 

 of the flagellum of which are rather elongated, with distinct, but 

 moderately long verticils, etc. These species have very distinct 

 pits on the humeral part of the mcsonotum, and a coiTesponding 

 double dot on the anterior part of the intermediate thoracic 

 stripe. Their forceps (Tab. IV, fig. 25, forceps of L. luteipennis, 

 half open) has nothing peculiar in its structure, and belongs to a 

 type rather common among the Limnophilse-. I have seen one 

 or two European species belonging to the same group. 



9. Limnophila tenuipes Say, imbecilla 0. S., recondita 0. S., 

 and the European discicollis Meig., are evidently allied; their 

 venation is the same; the inner ends of the second submarginal 

 and first posterior cells are in one line ; the small cross-vein is 

 perceptibly arcuated ; the first submarginal cell is short and has 

 a long petiole ; the prcefurca is long and forms a very straight 

 line with this petiole ; the auxiliary vein is comparatively short, 

 and ends before the inner end of the second submarginal cell ; the 

 marginal cross-vein is generally somewhat oblique, etc. The 

 joints of the flagellum are elongated, slender, with very long 



