340 TIPULID^E. 



The prevailing colour of bright yellow, marked with black, 

 should be regarded as a character of secondary systematic value, 

 yet it is remarkably uniform throughout the genus. The exceptions 

 simply reverse the colours, that is to say, the ground-colour is 

 mainly black, the markings yellow. In either case a little 

 acquaintance easily differentiates a Pachyrhina from the more 

 sombre hues of browns, yellows, or greys in Tipula. 



Another apparently constant character, which does not seem to 

 have been observed before, is the forking of the 4th longitudinal 

 vein with its attendant results. The lower branch of the 4th 

 longitudinal vein forks never later than at the base of the discal 

 cell, normally a little before it, so that the posterior cross-vein 

 being also placed exactly at the fork, the ivhole posterior side of the 

 discal cell abuts on tJie penultimate posterior cell. The ultimate 

 posterior cell is therefore not in contact with the discal cell when 

 the forking occurs before that cell, and only in punctiform contact 

 with it when the forking occurs exactly at the corner of the cell.* 

 Xormally, the furcation occurs just before the cell, sufficiently so 

 to give the appearance of a short cross-vein on the hinder side of 

 the discal cell, corresponding to the anterior cross-vein on the 

 front side of it.f Pachyrhina has one marginal, two submarginal, 

 and five posterior cells as in Tipula. 



Life-history. The life-history of several of the European species 

 is known. The larva lives under rotting leaves or in rotting 

 wood ; that of P. pratensis, L., in the roots of grass, according to 

 Gmelin and Fabricius. Schiner records that clouds of the larvae 

 of this species were blown about in the air during the year 1852 

 in Westrogothia. 



Table of Species. 



1. Antennae sub-serrate on underside 2. 



Antennae not sub-serrate 4. 



2. Pleura with a distinct shining black spot on 



the upper part of the sternopleura ; scu- 



tellum black, metanotum bright lemon- [p. 343. 



yellow plevrinotata, sp. n., <5 , 



Pleurae wholly yellow, no black spot ; scu- 



tellum and metanotum normally all 



yellow, the former sometimes with a 



black median stripe 3. 



?. Flagellar joints, except the 1st, wholly 



black serricortris, sp. n., p. 341 . 



Flagellar joints, except the 1st, yellow at [p. 343. 



the base puncticornis, sp. n., 



* Obviously also, in the latter case, the 2nd basal cell is also in punctiform 

 contact only with the discal cell. 



t Compare a similar passage concerning the 4th vein in Tipula (p. 296). 

 In both genera the posterior cross-vein is invariably placed at the angle 

 in the 4th vein, the fork of the latter occurring at, or very close to, the same 

 spot. No exception to this rule has come before me in any of the European, 

 North .American, or Oriental species examined. 



