NOV., '08] ENTOMOLOGICAL NEWS. 405 



Variations in the Wing Venation in some Tipulidae. 



R. W. Doane, Stanford University. 



(Plate XVII.) 



In all systematic work on the Diptera the wing venation is 

 a character that is used perhaps more than any other in sep- 

 arating the larger groups and in many instances is of real gen- 

 eric and often of specific value, so close does the venation hold 

 to a type. In the families with the more generalized type of 

 venation, however, there is more or less of a tendency to varia- 

 tion especially in the relative length and position of some of the 

 veins in the outer portion of the wing. 



In the Tjpulidae the presence or absence of the second pos- 

 terior cell and the length of the petiole by which it is joined to 

 the discal call are characters that are largely used. The cell 

 is always present in normal specimens of Tipula. I have be- 

 fore me a specimen of T. simplex Doane, in which this cell 

 is entirely wanting in both wings, the wings otherwise being 

 perfectly normal (See Fig. i; in all the figures only the out- 

 line of the wing and the venation is shown, as the marking 

 would in some instances obscure the point that we wish to 

 show). The wings of the male of this species are subject tc 

 considerable variation in size and shape and intensity of the 

 markings, but the venation is, as a rule, quite constant. (Com- 

 pare Figs. 2 and 3.) 



One of the principal characters that is often used for separat- 

 ing the genus Tipula from Pachyrhina is the presence or ab- 

 sence or short length of the petiole of the second posterior cell. 

 In Pachyrhina this cell is sessile or with a very short petiole, 

 while in Tipula the petiole is usually longer. There is con- 

 siderable variation in this respect in both genera, however, even 

 within the species, and indeed sometimes in the two wings of 

 the same individual as shown in figures 4 and 5, which are the 

 right and left wings of a specimen of Pachyrhina ferruginea, 

 more or less variation is often shown. In the right wing, Fig. 

 4, the second posterior cell has a very distinct and, for a 

 Pachyrhina, rather long petiole. In the left wing, Fig. 5, this 



