Systematic Position of the Genus Mycetobia, Mff. 113 



Turning to the Rhyphid^E^ we find that in Olhiogaster 

 (fig. 2 6) the labium differs from that of Mycetohia chiefly in 

 having the raentum completely fused on to the gular plate, 

 while the former, instead of the latter, provides the attach- 

 ment for the maxillary stipites. Ii/u/phus (fig. 2 a) presents 

 a very different structure : there is a well-marked median 

 organ situated between the labella, which is regarded by 

 Kellogg (' Psj'che/ vol, viii. p. 35()) as representing the 

 fused glossfe ; a small narrow plate is inserted between the 

 mentum and the gular plate, on each side of which last is 

 another plate, which may, perhaps, be regarded as the cardo 

 of the maxilla. 



A gular plate entirely comparable with that of the 

 Rhyphid.E occurs in Ptychoptera and in Trichocera, though 

 it appears to be absent in DLva. A similar plate is to be 

 found in at least some of the Brachyceea and in the 

 MusciD^, where it is fused with the head-skeleton ; it has 

 been figured for Musca by Wesch^ (J. E. Micr. Soc. 1909, 

 pi. iv.), who regards it as the mentum. 



Venation. 



The Rhyphid^ and Mycetophilid^ agree in having a 

 costa which does not extend beyond the tip of the wing, but 



^■^z Cu^ An 



Wing of (a) Mycetohia pallipes, Mg., (5) Olhiogaster sackeni, Edw. 



differ widely in that the former have a three-branched media 

 and a discal cell, whereas the latter never have more than a 

 two-branched media and no discal cell. 



At first sight it is not easy to connect these two types, but 

 if in the wing of Rhyphus we suppress the third branch of 

 the media, and with it the cross-vein forming the discal cell, 

 a condition very much resembling that of Mycetohia is arrived 



Ann. & Mag. N. Hist. Ser. 8. Vol xvii. 8 



