THE CRANE-F LIES 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 
Es Tergal valve N\ 
A D 
Tergal valve 
7 
C 
BE 
Fic. 131. FEMALE HYPOPYGIUM, OR OVIPOSITOR 
A, Trichocera bimacula, lateral aspect. B, Tanyptera frontalis, lateral aspect. C, Tipula 
longiventris, 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 arctica, 
T. longiventris (fig. 131, c), T. labradorica, T. serricauda; all the valves 
may be short and fleshy, superficially resembling the male genitalia but 
being smaller —as in the Cylindrotominae and Styringomyiini, and in 
Tipula bicornis, T. megaura, T. parshleyi (fig. 131, 8), T. morrisoni, T. nobi- 
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 
