( clviii ) 



that it folds up and is ordinarily imperceptible, but it is 

 capable of so long an extension when necessary as to enable 

 the clasping organs to be emitted almost below the genital 

 aperture of the female. The organs are extremely varied in 

 form — one genus difiering from another as is the case in the 

 other orders ; at the same time, even with my own limited 

 experience, I think I should know whether I was examining 

 a preparation from a Dipteron without difficulty and without 

 being informed of the order. It is only possible for me to 

 consider one or two species in some of the families in the two 

 great divisions, the Orthorrhapha and the Cyclorrhapha ; in the 

 former the Tipulidae have the organs large and frequently 

 complicated. 



Tipula paludosa 



has the tegumen, or its equivalent, in the form of a very 

 large and deep bonnet-shaped hood, within which are two 

 pairs of prominent lobes, the shorter ones pointed, the larger 

 ones rounded, whilst externally is the probable equivalent of 

 the harpagones, which are largish, somewhat spatulate processes 

 with narrow deeply curved hooks above them ; on the venter 

 are two sensory pads furnished with short teeth, these doubt- 

 less are extended on the venter of the female and probably 

 act as excitants. The dorsum is provided with clusters of 

 strong spines ; the sedceagus is an exceedingly long and very 

 fine tube. 



Pachyrrhina lineata. 



The tegumen in the genus is only bridged over very narrowly 

 on the dorsum, being composed of two largish rounded lateral 

 plates, to which are articulated the harpagones ; these are 

 smallish with a solid rear, but with the apex deeply bifid, giving 

 it a pincer-like shape, the upper jaw having a vertical, hollowed, 

 somewhat spatulate process ; the ventral pads are slightly 

 different in outline from those in the genus Tipula, but are 

 quite evidently functionally similar. 



Psiloconopa meigenii, 



as representing the Limnobidae, has its organs enclosed in a 

 globular case divided more or less centrally. Not having 



