872 CHARLES PauL ALEXANDER 
caudal margin is produced into a strong median lobe (Plate L, 287), or 
into two slender lobes (Plate XLIX, 271 and 272), one on either side of 
the median line. The writer regards the ninth tergite as offering the 
surest and easiest characters for identifying the species of Tipula, and 
its various forms are accordingly illustrated in this paper. 
The ninth sternite may be either prominent or insignificant. It bears 
on its caudal part the ninth pleurites, or pleural region. In primitive 
forms the pleurites are distinct, being cut off by the pleural suture 
(fig. 129, a); in other forms the suture is obliterated to a greater or less 
degree and the pleural region is thus immovably attached to the sternite. 
In very many Tipulinae (as in most species of Nephrotoma and many 
species of Tipula), the pleural suture is represented only by a short, curved 
impression on the ventral side of the fused ninth sterno-pleurite. In the 
genus Longurio the ninth sterno-pleurite is exceedingly elongated, the 
pleural region being situated at the caudal end and bearing at its apex 
the pleural appendages, which, in a position of rest, lie in the dorsal con- 
cavity of the elongate sterno-pleurite. In some species — T7pula parshleyi 
(fig. 129, B, and Plate LV, 354), 7. trinidadensis, T. macrosterna, T. glad- 
zator, and others — it is the eighth sternite that is so greatly enlarged, the 
ninth sternite being comparatively small and often lying in the dorsal 
concavity of the eighth sternite. The ninth sternite is usually more or 
less incised on the mid-ventral line by a deep notch, which in some cases 
seems to bisect it; such deep notches are spoken of as profound incisions. 
The only paired element of the hypopygium consists of the ninth 
pleurites, there being one pleurite on either side of the organ. Usually 
the pleurites are small and oval, but in some cases they are greatly pro- 
duced, as in Tipula macrolabis and T. macrolaboides (Plate LIII, 322 
and 323); in other species they are curiously twisted and semi-coiled, 
as in 7’. streptocera; while in many species an intermediate condition is 
found in which the pleurite is produced in a moderate degree only (as 
in T. loewiana, T. mandan, and others). The pleural appendages are 
usually two in number. The outer one is more or less fleshy and is of 
various shapes and sizes in the different groups. In the genus Nephrotoma 
it is broadly oval to elongate-oval and usually pointed, in many species 
the tips being greatly produced and attenuated. In the genus Tipula 
it may be very tiny, cylindrical, and tending to be reduced, as in the 
