112 



Mr. F. W. Edwards on the 



described by Kellogg simply as tlie " basal labial sclerite " ; 

 Frey liomologizes it with the mentum. I am by no means 

 certain that Frey's view is correct, since it usually shows a 

 median groove or suture, indicating that it may have arisen 

 by the fusion o£ paired structures. For convenience, how- 

 ever, it may be well to follow Frey. 



In Mycetophilid^. the labium consists of the two large 

 labella, usually two-jointed, attached to the mentum, at the 

 base of whicii an ill-defined subnientum is sometimes 

 discernible. Mycetohia differs from all the other MycETO- 

 PHILID^ * in possessing at the base of the labium a large 

 hairy gular plate (figs. 2 c and 3 c) covering the forked end 



Fill. 4. 



Under surface of head of («) Ditomijinfasciata, Mg., (b) Phifijiira nemo- 

 ralis, Mg., (c) Empalia vitripennis, Mg., {d) Phronia forcipula, 

 Wiun. Note absence of gular plate, except in c; also great 

 development of the maxillary stipites in c and d. 



of the mentum t; to the anterior angles of this plate are 

 attached the bases of the maxillary stipites. The only other 

 Mycetophilid in which I have found any gular plate at all is 

 Empalia vitripennis ; in this case the plate is very small, 

 bears no hairs, and is quite remote from the labium (fig. 4 c). 



* I have examined from this point of view the following .species : — 

 Biadocidia ferniginosa, Ditomyia fasciata, Syinmei-us annulatus, Bolito- 

 j)hila ci7ierea, Macrocera stigma, Platyura fasciata, P. ne^noralis, Myco- 

 nn/ia inscisurata, Sciophila hirta, Empalia vitripennis, Tetrayoneura 

 sylvatica, AUactoneura cincta, Buletina sciarina, Docosia valida, Leio- 

 myia subfasciata, Phronia forcipula, Exechia fungormn, and Mycetophila 

 punctata. 



t It is possible that this " gular plate " is really the true mentum, 

 which in that case is absent in the other Mycetophilid^. 



