290 Mr. W. Wescbe on systematic affinities of the Fhoridaj 



forcipes interiores and j^a/^Ji genitalium and contains the 

 penis. Usually these organs are hidden in tlie cavity of 

 the hypopygium. In P. incrassata are found paired hooks 

 and plates, the latter covered with a minute sculpturing 

 of the chitin identical with that found on parts of the 

 genitalia of PcripJancta. These hooks and plates surround 

 the penis, which is formed of a hyaline membrane based 

 on a chitinous ring, and with some structure and tubercles 

 on one side. The ejaculatory duct runs up through the 

 chitinous ring, and opens on the side opposite the tubercles. 

 The penis is asymmetrical, and is the simplest and rudest 

 that I know in Diptera. The spinus (unless it has soldered 

 into the back of the penis, and is present as the "structure" 

 alluded to above), and the apodemes, appear to be absent. 

 P. concinna has a more elaborate penis, and its base is 

 fused with a lever wliich probably represents the great 

 apodemes, and sensory structures represent the palpi 

 genitaliura and forcipes interiores, but this last portion of 

 the genitalia is difficult to understand and requires more 

 material for study. In T. atcrrima, though the containing 

 plates of the lower part arc easily differentiated as forceps 

 interiores and palpi genitalium, the penis is minute and 

 unsymmetrical, and seems to be a membrane based on a 

 ring as in P. incrassata, hut the ejanhlatory sac and apodc^ne 

 are quite obvious. 



A fourth species, P. rujlpes ?, has the penis and sur- 

 rounding parts of another type. The variations generally 

 are much greater than usually found between species, or 

 even genera in the Muscidse. One cannot but be struck 

 by the extraordinary anomalies in the parts ; all these 

 insects have the organs representing the forcipes superiores 

 and forcipes inferiores of a more archaic type than those 

 found in the Mycetophilidse, together with (in Trineura) 

 an ejaculatory apparatus such as is found in the highly 

 specialised Muscida3. 



In Conicera atra, Mg., the genitalia are far more sym- 

 metrical and appear to approximate to the form that is 

 found in the Lonchopterida3, and both suggest a relationship 

 to Dolichop>us. 



The genitalia (female). The ovipositor is fairly simple ; 

 it is similar in general plan to that found in the 

 Dolichopodidas, that is to say it is moderately long, pro- 

 trusile, and with distinct joints, but lacking the chitinous 

 rods found in the Muscida). At the distal extremity are 



