DICBANOMTIA. 365 



1st vein. The 2nd longitudinal vein begins in the middle of the 

 wing, either at an acute angle or in a curve of varying sweep, 

 gently Insinuate ; its basal section (that is to say, that portion 

 from its origin to the emergence of the 3rd vein, or the praefurca) 

 straight or rather distinctly curved, varying from one-half to 

 one-fourth the total length of the vein. The 3rd vein with the 

 basal section of varying length, according to the species, but 

 tolerably constant in each species ; * its course also varies con- 

 siderably, sometimes gently bisinuate, in some species forming 

 nearly a rectangle both at its origin from the 2nd and at its elbow, 

 in most species parallel to the 2nd longitudinal vein or slightly 

 diverging or converging at the tip. Owing to the 3rd vein 

 emerging from the 2nd at some distance beyond the base of the 

 latter, the submarginal cell is always considerably shorter than 

 the marginal cell, and nearly always longer than the 1st posterior 

 cell. Anterior cross-vein always situated at the upper basal 

 corner of the discal cell. Discal cell generally present,t generally 

 more or less elongate, usually pentagonal, the distal side formed 

 (as is the general rule in TIPULID.E) of two short veinlets forming 

 the basal sides of the 2nd and 3rd posterior cells, of which the 

 3rd is generally a little longer than the 2nd. When the discal 

 cell is absent, it is generally coalescent with the 2nd posterior 

 cell. The 4th vein, when the discal cell is open, has either the 

 upper or the lower branch forked, in most cases the latter. 

 Posterior cross-vein placed exactly at or a little before the base 

 of the discal cell, but its position varies to an appreciable degree 

 even in the same species. The 5th, 6th, and 7th longitudinal 

 veins nearly straight, or slightly curved downwards at the tip. 



Range. Europe, North America, West and South Africa, the 

 Orient, and Australasia. 



Notes on the venation. The marginal cross-vein is generally in 

 a line with the upturned tip of the 1st longitudinal vein, but in 

 some species (the feature also adventitiously occurring in an 

 otherwise normal species) it bends a little proximally at its upper 

 end, thus making it appear as if the 1st vein itself turned down- 

 wards at its tip into the 2nd vein, whilst being joined by a short 

 cross-vein to the costa. 



There is a figure in Needham's plates of an American species 

 (D. immodesta, Os. Sac.) in which the 1st longitudinal is distinctly 

 shown turning down into the 2nd at its end, no cross-vein being 

 shown at all. This, it seems to me, may well be an error, as the 



* In I). fascipennis, Brim., it is as long as the basal section of the 2nd vein; 

 in D. ornatipes, Brun., it is rather shorter than the auxiliary vein. 



t Absent in at least two North American species (D. iinmodesta, Os. Sac., 

 and cinerea, Doane), also in some Oriental species (I), abscns, Brun., kobusi, 

 Meij., and tcnella, Meij.). 



| Osten Sacken mentions a North American species, D. pubipennis, which 

 normally has the discal cell closed, but out of twenty specimens of it seen 

 by him, five had it open, and in each case it coalesced with the 3rd and not 

 the 2nd posterior cell. 



