220 R. E. SNODGRASS. 



linear membranous area. The dorsal part of each plate is distin- 

 guished from the rest by an oblique suture that cuts off on each side 

 a triangular marginal plate having the apex forward. The two 

 dorsal plates thus formed may represent the tergum divided by a 

 median line of membrane. Each plate makes a sort of step poste- 

 riorly by turning downward and then posteriorly again. The pleura 

 are entirely separated from the lateral sternal plates. Each is some- 

 what reniform in shape, with the convex side posterior and pro- 

 longed into a long, sinuous, tapering arm (fig. 103). This is similar 

 to the much smaller process on the pleurum of Tipula lamellata and 

 of T. unicincta. 



The apical appendages have an unusual shape (fig. 105). There 

 is on each one large triangular lobe (B) attached by an angle which 

 forms a thick peduncle. From its position and general shape this 

 lobe would appear to be the middle appendage of the ordinary three. 

 Arising from the outer side of its base are two much smaller lobes 

 (A and C). Each is flattened and expanded distally, and the two 

 have a common base. One is anterior and turns forward, the other 

 posterior and turns backward. They may be the first and third 

 appendages. 



The central vesicle, penis and guard have ordinary forms. The 

 V-shaped bar between the posterior arms and the central vesicle has 

 the tips of its arms embracing the base of the anal tube. 

 Tipula spectabilis Doane (PI. XVIII, figs. 156, 158, 159, 160, 161). 



This is a large species, with a specially large hypopygium. The 

 latter stands almost vertically upon the eighth segment (fig. 160). 

 The eighth sternum is large and prolonged so far posteriorly that it 

 projects for some distance back of the vertical sternum of the hypo- 

 pygium. The posterior end of the eighth sternum is truncate and 

 deeply notched. The part of the margin on each side of the notch 

 forms a large, inward-turned flap bearing a large brush of long hairs. 



The tergum of the hypopygium consists of two plates entirely sep- 

 arated by membrane along the mid dorsal line (fig. 156). The ante- 

 lior edge is widely emarginate. Posteriorly each plate of the ter- 

 gum is produced into a lateral and a more median point, while from 

 between the two plates there projects caudally a short tapering pro- 

 cess which is grooved along its dorsal side. 



The sternum consists of two lateral plates as in other species. 

 But here they are united below by a posterior bridge of chitin as 



