266 TIPULTDiE. 



The principal features of the venation are the great length of 

 the auxiliary vein and of the t^^•o basal cells, the development 

 of the latter throwing the distal and posterior veins mainly into 

 the apical part of the wing ; also of the presence, normally, of a 

 discal cell, which, with the sole exception of the Ehyphid.i:, is 

 absent iu all the other families of this suborder. The veins in 

 their ultimate subdivisions along the margin of the wings are 

 usually ten to twelve in number, rarely nine {Toxorlmia). One 

 genus (CJimiea) is wingless. 



For the last half century or more, the TiPULiUiE have always 

 been divided into three subfamilies, designated respectively the 

 Ptychopteein.e, Tipulin.t:, and LimnoisiinvE. Dia-a, as a sub- 

 family DixiNiE, has been included by one or two authors, even as 

 late as 1888 by Verrall, and placed next to the Ptychopteeinvi:, 

 and Chionea has been included by some and withdrawn by others.* 

 Schiner placed Bira with a few other genera {Blejiharocera, Macq., 

 Macropeza, Mg., Spodins, L^^•., Pachyneura, Zett., Corynocera, Zett., 

 and Orphnephila, Hal.) which he considered anomalous, at the end 

 of the Nematocera. Chionea he included in the TiPi'LiD.i: as an 

 anomalous genus, separating it from the three subfamilies quoted 

 above. 



These subfamilies have been almost universally recognised until 

 comparatively recently, when several authors have regarded them 

 as separate families, Dixa also forming another family. Whether 

 they should rank as families or not, it seems to me that they 

 should be at least placed in juxtaposition in a systematic sequence 

 of families. They are, however, to me so essentially similar in 

 structure and general resemblance, that it seems imperative to 

 include them again under one family name. 



It is impossible to assume that there is as much distinction 

 between the PTYcnoPTEiiiiNyE and even the rest of the Tipulidte 

 combined, as there is between it and any other family of Nemato- 

 CERA, say, CuLiciD^ or ChironomidvE. There is therefore still 

 less difference, from a "• family rank " point of view, between the 

 TiPULiN^ and the Limnobiin^. In spite of the admitted tend- 

 ency of present-day zoologists to multiply families, genera and 

 even higher ranks, I see, personally, in the whole of the order 

 Diptera, no legitimate grounds for the creation of any new 

 families.t 



The TiPULiD^, as a whole, have always appealed to me as a 

 peculiarly homogeiieous family with quite well-defined limits, 

 with the sole exception of Dixa, a genus, however, that is more 

 nearly alHed to the Tipulidje than to any other family. 



In the recent Catalogue of Palsearctic Diptera, by Kertesz, the 

 Ptychopterin^, raised to family rank, with the DixidyE and 



* This genus is now definitely recognised as belonging to the Tipulid^. 

 t Vide "Taxonomic values in Culicid^,'' in Eec. Ind. Mus. iv, p. 53 (1911), 

 in which I deprecate the multiplication of genera and species iu this family. 



