LIMNOBIA. 397 



of hair are longer. Thorax &nd abdomen practically as in Dicrano- 

 myia, although generally rather more robust in most of the species. 

 Genitalia of male with a large fleshy 1st joint, the 2nd formed 

 of a large horny hook ; intermediate additional organs are some- 

 times present ; a ventral plate. Ovipositor of female much like 

 that of Dicranomyia (vide ante). Legs stouter than in Dicranomyia, 

 but sometimes of great length ; tibise without terminal spurs, 

 empodia indistinct or absent, ungues with several teeth below, 

 giving them a pectinate appearance. Wings generally shorter and 

 broader than in Dicranomyia ; one submarginal cell, four posterior 

 cells, discal cell always closed.* 



Auxiliary vein ending some distance beyond origin of 2nd vein ; f 

 the marginal cross-vein, generally falling very near the middle of 

 the marginal cell, is placed at the tip of the 1st longitudinal vein 

 or a little way before it, generally surrounded by the stigma. In 

 some species the appearance of the 1st A'ein gives the impression 

 that it turns down at the tip into the 2nd vein, with a cross-vein 

 between it and the costa, but in such cases the vein must be con- 

 sidered to pursue its normal course, connected as usual with the 

 2nd longitudinal by the normal marginal cross-vein ; the same 

 appearance occurs not infrequently in species of Dicranomyia (as 

 noted under that genus). In general the venation in Limnobia is 

 more uniformly consistent than in Dicranomyia ; the basal section 

 of the 3rd vein is more nearly of a uniform length i ; the discal 

 cell is shorter than in Dicranomyia, more often approaching a 

 square shape with one corner cut off ; the position of the posterior 

 cross-vein varies from distinctly before the base of the discal cell 

 (in festiva) to almost at its middle (longinervis). 



Range. World-wide, nearly two hundred species being known. 



The chief characteristics which distinguish Limnobia from 

 Dicranomyia are : (1) its generally more robust nature, larger size, 

 and brighter colouring ; (2) the position of the tip of the auxiliary 

 vein, which ends much further distally than in Dicranomyia, in 

 which it ends approximately opposite the origin of the 2nd vein ; 

 and (3) the different structure of the male genital organs, this 

 latter character being naturally the most difficult one to observe in 

 dried insects. 



Many of the species are of considerable size, some having legs 

 of great length, as in the European species L. bifasciata, Schrk., 



* Personally, I have seen no species with au open discal cell, even in an 

 accidental case, and Osten Sacken notes the same fact, yet of course it may 

 occur sometimes adventitiously, if not specifically. 



t The only exception among the Oriental species is festiva, Brim., in which 

 it ends opposite the origin of the 2nd vein, but the whole appearance of the 

 species is so Limnobia-like that it is, at least provisionally, placed in this 

 genus. The next nearest species of this nature is tinctinervis, Brim., in which 

 the auxiliary vein ends at the middle of the praefurca. 



J At least in all the Oriental species, and such European ones as are 

 available for comparison. 



