872 Charles Paul Alexander 



caudal margin is prodiiccHl 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 — Tipula parshleyi 

 (fig. 129, B, and Plate LV, 354), T. trinidadensis, T. macrosterno, T. glad- 

 iator, 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 Tipida macrolabis and T. macrolahoides (Plate LIII, 322 

 and 323) ; in other species they are curiously twisted and semi-coiled, 

 as in T. 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 Ijroadly 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 



