AMERICAN DIPTERA. 227 



The body of the hypopygium is entirely undivided into tergum, 

 sternum or pleura (fig. 49). The tergal part is very short (fig. 47), 

 while the sternal part is correspondingly very large. Through this 

 disproportion between the dorsal and ventral surfaces the posterior 

 rim is almost horizontal and the genital chamber opens upward. 

 The tergal region bears on each side a large horn -like process (figs. 

 47 and 49, a), the two diverging posteriorly and laterally. The 

 sternum has a deep median notch on the posterior margin, but is 

 not otherwise divided. 



There are three apical appendages on each side. The first (figs. 

 47 and 49, A) is a large plate, convex outwardly and concave 

 inwardly, also bent in the latter direction, and expanded and notched 

 terminally. The second (fig. 49, B, and fig. 46) has a plate like 

 basal part, but distally it tapers into a long, slender, densely chitin- 

 ous and somewhat spatulate arm directed anteriorly within the first 

 appendage. The third appendage is slender and angularly bent for- 

 ward. It lies within the second and is entirely concealed in the 

 genital chamber. 



The central vesicle, penis and guard have the forms characteristic 

 of Tipula. The penis makes a short curve forward into the eighth 

 segment. The guard is a simple, compressed structure, with a deep, 

 narrow, slit like, median groove along the dorsal surface. 



The anal tube is the same as in Tipula. 



TRANS. AM. ENT. SOC. XXX. JULY. 1904. 



