40 Dr. D. Keilin on the Larve &e. of 
The study of the larvee and pupz of Ditomyia and Sym- 
merus shows clearly the great similarity in structure of nearly 
all their organs. It also shows, on the other hand, that the 
larval and pupal structure of these two genera is totally 
different from that of all the Mycetophilide. 
The difference is especially striking in the structure of 
the antenne, mandibles, maxille, and labium, with their 
palps, the sensory organs, respiratory system, structure of 
the spiracles, the salivary glands, and, finally, the form of the 
pupe. 
These two genera must therefore be re-united in a special 
family, the Ditomyide, which itself must be completely 
separated from the family of the Mycetophilide. 
From the study of the larval and pupal characters it 
follows that the family Ditomyide must occupy among the 
‘Diptera Orthorrhapha Eucephala, of Brauer, a position 
equally important with that of the Mycetophilidz, Bibioni- 
nid, Rhyphide, &e. 
As to the relations of this new family to the others we 
can state only that the larve of Ditomyidz bear a closer 
resemblance to the larvee of Bibionidze than to those of any 
other Diptera, and more especially when we compare their 
labra, mandibles, maxillee, and the structure of the spiracles. 
The subfamily Mycetobiine of Winnertz (1861), composed 
of the genera Mycetobia, Mesochria, Ditomyia, and Symmerus, 
must therefore completely disappear, as Mycetobia (and with 
it, according to Edwards, Mesochria) must be transferred to 
the Rhyphidz ; while the two others go to form a separate 
family, Ditomyide, completely separated from Myceto- 
plilidee. 
I must express here my best thanks to Mr. F. W. Edwards 
for sending me tle specimens of Ditomyia and Symmerus 
larve. I may say that it is his re-discovery of these larvee 
which has enabled me to accomplish this study. 
REFERENCES. 
Durour L. (1849.) “ Histoire des Métamorphoses du Rhyphus fenes- 
tralis et du Mycetobia pallipes.” Ann. de la Soe. Entom. de 
France, 2° série, t. viii. pp. 195-210, pl. 7. 
Epwarps, F. W. (1916.) “On the Systematic Position of the Genus 
Mycetobia, Mg. (Diptera Nematocera).” Ann. & Mag. Nat. Hist. 
ser. 8, vol. xvi. pp. 109-116. 
——. MBS. Notes on Ditomyia and Symmerus, see pp. 36 & 39 of this 
paper. 
