Systenmtic Position of the Genus l\rycetobia, M<j. 109 



At M. Keiliii's 8U<^gestion, I have devoted some study to 

 tlie adult structure of the MYCirroPiriLlD.E aud RilYPillD.E, 

 ill order to ascertain whether any characters can bo I'ljuiid to 

 support conclusions based on the study o£ larvre and j)upaj. 

 Without clainiinn^ to have made at all an exhaustive in- 

 vestigation, I think I may safely state not only that such 

 cliaracters do exist, but that they should be taken into account 

 in the classification of the Di|)tera as a whole. 



In order to explain clearly what these characters are, it 

 will be necessary to give a brief comparative account of the 

 structure of the mouth-parts and the venation in the two 

 families in question. In referring to the mouth-parts of the 

 ]\IyceT0PIIILID.E I am relying partly on my own observations, 

 but chierty on the excellent work lately published by Dr. R. 

 Frey (Acta Soc. Fauna et Flora Fennica, xxxvii. no. 2, l'J13). 



Mouth-parts. 



ManrliJdes. — There seems to be no trace of these in either 

 of the two families. 



Fi-. 1. 



Labrutn, epipharynx, and liypopharynx of (a) Olhiogaster africanus, Edw., 

 (b) Mi/phiisfeyiestra/is, Scop., and (c) Mycetobia pallipes, Mg. 



Lahrum. — In both the MYC'ETOPHiLiDiE and RHYPHiDyE 

 the labrura is very much reduced, being, as a rule, almost 

 entirely membranous. There is, nevertheless, a considerable 

 amount of variation. In the Rhyphid genus OUnogaster a 

 distinct cliitinized piece is present on the upper side, the lower 

 side (the so-called epipharynx) being chiefly membranous ; 

 in Rhyphus the upper side is membranous, the lower side 

 more or less cliitinized and provided with a fringe of Indrs 

 towards the tip; in Mycetobia the whole labrum is mem- 

 branous. 



