174 



NORTH AMERICAN DIPTERA. 



with two series of booklets, the two projecting backward 

 in the middle being stont and curved; below these there 

 is a deep, transverse cleft, on the under side of which is 

 a rounded lip. 



Fig. 62. Acanthotnera, sp. wing. 



In both Acanthotnera and Rhaphiorhynchus the face 

 may be produced conically or not at all. The two genera 

 are distinguished by the structure of the second joint of 

 the palpi, in Acanthotnera slender, in Rhaphiorhynchus 

 stout and pointed. Both genera may have a spine on 

 the under side of the hind femora. 



Osten Sacken has already commented upon the sup- 

 posed distinctions between Acanthotnera and Rhaphio- 

 rhynchus^ making it clear that only the palpal character 

 is of service, and even that is doubtful since it may be 

 only sexual. I have examined five or six species of the 

 family and am very skeptical of the validity of Rhaphio- 

 rhynchus. 



There are apparently no valid nor just reasons for the 

 retention of the generic name Acanthomcra. Wiedemann 

 more than once, arbitrarily and without giving reasons, 

 rejected the earlier names of genera and species for ones 

 of his own creation, and the present seems to be one of 

 the most flagrant examples. The description and figure 



