The Crane-Flies of New York — Part I 



875 



of four horny or chitinized pointed valves, which are paired — there being 

 two dorsal (tergal) and two ventral (sternal) valves. These valves are often 

 acicular and are used for the insertion of the eggs in oviposition. In most 

 species they are curved upward so that the concavity is on the dorsal 

 side, but in the genus Trichocera (fig. 131, a) and some of its near allies 

 the ovipositor bends downward, the concavity being on the ventral side. 

 As wide a range in structure of this usually homogeneous organ as 

 occurs in the group, is found in the genus Tipula. The tergal valves 



Tergal i^a/i^p 



STema/ ^a/ye 



■Terqa/ i/cr/i/'e 



Fig. 131. female hypopygium, oh ovipositor 



A, Trichocera bimacula, lateral aspect. B, Tanyptera frontalis, lateral aspect. C, Tipula 

 longivenlrvi, dorsal aspect. D, Tipula piliceps, dorsal aspect. E, Tipula parshleyi, dorsal 

 aspect 



are usually longer than the sternal valves (fig. 131, c), and both tergal 

 and sternal valves assume a variety of shapes. They are often slender 

 to subacicular; the tergal valves may be sharply serrated on their outer 

 faces, as in many Arctic and North Temperate species — Tipula ardica, 

 T. lorigiventris (fig. 131, c), T. labradorica, T. serricauda; all the valves 

 may be short and fleshy, superficially resembling the male genitaUa but 

 l)eing smaller — as in the Cylindrotominae and Styringomyiini, and in 

 Tipula bicornis, T.megaura, T. parshleyi (fig. 131, e), T. morrisoni, T. nohi- 

 lis, and other species; all the valves may be short and truncated across 

 their tips but strongly chitinized, as in Tipula mandan; or the sternal 



