214 R. E. SNODGRASS. 



plates set on edge, with the posterior end of each turned downward 

 like a pistol grip (fig. 82, lateral view). A transverse V-shaped 

 plate, with the apex greatly prolonged and trough-like, connects the 

 two lateral plates and forms a wide groove lodging the penis (fig. 

 81, dorsal view). 

 Tipula retusa Doane (PI. XIII, figs. 84, 85, 86, 87, 88). 



The eighth sternum is extraordinarily large and very convex be- 

 low. Its posterior margin is horizontal. The eighth tergum, on the 

 other hand, is small and mostly concealed beneath the seventh ter- 

 gum (fig. 84). The end of the eighth segment thus forms a cup- 

 shaped cavity directed upward, into which is set the base of the 

 hypopygium. The sternum bears posteriorly on each side a wide 

 brush of hairs directed ventrally. 



The hypopygium projects almost vertically from the eighth seg- 

 ment. It has in general the form of a frustum of a cone. There 

 are well developed triangular pleural plates present. The halves of 

 the sternum are fused below along their entire length. Posteriorly 

 the sternal margin is emarginate. An elongate, club-shaped lobe 

 (fig. 84, a) arises on each side from the margin of the sternum, lat- 

 eral of the median notch," and projects posteriorly. The tergum is 

 almost divided into two plates (fig. 86) by a deep notch on the pos- 

 terior margin, and a still deeper one on the anterior. The two leave 

 only a very narrow connecting bridge somewhat back of the centre. 



There are three apical appendages on each side (fig. 85). The 

 first (A) is the smallest, being slender, compressed and clavate. The 

 second (B) is the largest. It is expanded distally and ends in a flat 

 point directed forward. Its anterior edge bears the ordinary elon- 

 gate elevation, ending with a free lobe above. The third (C) is 

 entirely separated from the second. It is widest basally and tapers 

 distally to a narrow elongate process abruptly bent posteriorly. 



The central vesicle (fig. 88, c. v.) has the anterior arms rather 

 slender, but the posterior arms and the apodemes are relatively large. 

 The penis (p.) first goes downward and then turns forward to about 

 the seventh segment. It then again goes posteriorly to below the 

 central vesicle where it turns dorsally along the vertical floor of the 

 genital chamber. The tip is curved anteriorly. The guard of the 

 penis (fig. 87) consists of two high and relatively short plates united 

 by their lower edges, and inclosing, thus, between them a deep 

 trough-like space. From the lower posterior angle of each a long, 



