AMERICAN DIPTERA. 191 



terminal part is simply turned up, in others the distal half curves 

 upward and then forward again. Under the microscope a tube can 

 be seen fitting closely inside of the guard By pressing on the cover 

 glass it can be proved that this appearance is not merely an optical 

 effect, for the outer tube clearly separates from the inner. By break- 

 ing the structure apart, however, the two tubes break with such even 

 fractures that they cannot be easily demonstrated in this way. The 

 inner tube is the penis. 



Arising from the sides of the genital chamber, and apparently from 

 the inner faces of the pleura, above the base of the guard, are the 

 second gonapophyses. Each is a biramous process, the two arms 

 forming a large angle with each other (fig. 34, gon. 2), and is sup- 

 ported by an arm-like apodeme (ap.) extending forward and upward. 



Genus EPIPHRAGMA O. S. 

 This genus also belongs to the Limnophilina, and presents the 

 same type of structure as Limnophila. 



Epiphragma fascipennis Say (PL IX, figs. 13, 15). 



The abdomen is somewhat long and slender. The hypopygium 

 forms only a slight enlargement. The sternum of the eighth seg 

 ment is much larger than the tergum, and extends posteriorly 

 beneath the ninth segment. 



The body of the hypopygium is undivided by sutures; the tergal 

 margin is slightly convex and notched, the sternal margin is entire. 

 The pleura are extraordinarily large triangular lobes, their bases are 

 high and almost meet each other dorsally (fig. 13). Each lobe bears 

 two apical appendages directed inward and forward. The outer and 

 more ventral one is blunt and cylindrical, the other is more dorsal 

 but is mostly concealed by the outer, and is hook-like. 



The guard of the penis is a narrow, triangular structure, having 

 the tip somewhat prolonged and curved upward. The penis itself is 

 a short rod-like tube, arising just in front of the base of the guard 

 from two long prong-like roots, resembling the tines of a fork. 

 Between them the ejaculatory duct enters the penis. 



The second gonapophyses are of rather curious shape (fig. 15). 

 Each consists of a long, slender, tapering arm lying along the side 

 of the genital chamber, and arising from the lower end of a vertical 

 rod lying against the anterior wall of the genital chamber, and pro- 

 jecting a little out of it dorsally (fig. 13, gon. 2). Attached to the 



TEANS. AM. ENT. SOC. XXX. JULY. 1904. 



