TIPULID.E. 273 



produced simply by the invagination of the posterior face of the 

 segment " (Snod(/rass). 



The intromittent organ, or penis, is attached to the back or 

 dorsal part of the genital chamber in the TiPULiN^i;, and arises 

 from the floor of tliis chamber in the LiMiyoBiiivr.i:. It is very 

 slender and of great length, its tip protected by a piece acting as 

 a guard, the base greatly swollen ; this part being known to 

 Dufour, as the vesicula centralis. 



The ovipositor of the female is very much less variable in 

 structure than the male organs of generation, being so remarkably 

 uniform throughout the family as to constitute one of its leading 

 characteristics. Tiie standard form is that of two pairs of 

 elongate, pointed, greatly arcuated or quite straight valves, the 

 upper pair always longer than the lower (except in Trichocera),t\\e 

 latter being not only shorter in actual length but set further 

 back. The valves lying as a rule tightly closed, the whole 

 organ appears as an elongated cylindrical termination to the 

 abdomen, and it is in most eases of a reddish, yellowish or 

 brownish colour, or some intermediate shade. The conspicuous 

 nature of the ovipositor differentiates it easily from the two 

 hardly projecting inconspicuous valvules thf^t represent the female 

 genital organs in the other families of nematocerous Diptera. 



" The external sexual apparatus of the male consists of a forceps^ 

 by means of which the end of the female abdomen is seized from 

 below, a little before the ovipositor, in such a manner that the 

 latter organ is stretched out on the upper part of the abdomen of 

 the male. This done, the male, with a second, inner clutching 

 apparatus, seizes the orifice of the inner genital organs of the 

 female and adjusts thereon for copulation."* 



Legs. Always long aud thin, practically always microscopically 

 pubescent, the pubescence being generally visible under slight 

 magnification ; in certain genera and species it is conspicuous to 

 the Jiaked eye, bu.t there is no instance of long hairs on the legs, 

 and bristles are also entirely absent thi'oughout the family. The 

 coccce are sometimes lengthened but never unduly enlarged and 

 never to such an extent as in the Mycetophilin.!:. The femora 

 are often distinctly but slightly thickened at the tip ; in the 

 genus Gymnastes very considerably so, more so than in any genus 

 known to me. The femora are never dentate as in the Chironomid 

 genus Geratopoijon. The tihicv in many groups possess spurs at 

 their tips; in all cases where these spurs occur they are present 

 in all three pairs of legs, often being minute and hidden amongst 

 the rather longer and stifFer hairs that are generally found to\\-ards 



''^ Osten Sacken, Mouog. N. Amer. Tip. The notes on the genitalia of the 

 North American species in this monograph are very vahmble, as, in the intro- 

 duction to the work, tiie author states that most of the examinations of these 

 parts were from living specimens, the true form of the organs therefore being 

 observable. 



