Mycetobia, Ditomyia, and Symmerus. 3 
13. Respiratory system is amphi- 18. Respiratory system is either 
pueustic with only two pairs hemipneustic (fig. 3) with one 
of functional spiracles: (1) pair of prothoracic and seven 
prothoracic and (2) postabdo- pairs of abdominal spiracles, 
minal, or propneustic (Polylepta ox 
Diadocidia), or  apneustic 
( Ceroplatus). 
14. Alimentary duct without ante- 14. Alimentary duct with a pair 
rior coeca, of anterior lateral ceca. 
15. Anus ventral. 15. Anus terminal or subterminal. 
16. Salivary glands snort. 16. Salivary glands very long. 
17. Hypoderm of posterior seg- 17. No special large cells in hypo- 
ments of larvee, which sur- derm of the posterior end of 
rounds the anal cleft, is the body. 
composed of very large and 
thick cells. 
18. Pupe strongly chitinised with 18. Pupe with thin chitin and 
rows of small hooks on the without. the rows of short 
abdominal segments and spines or hooks, 
especially on the posterior 
end of their body. 
All these characters show us clearly that the difference 
between the larva of Mycetobia and those of Mycetophilide 
(s. 1.) is as striking as its resemblance to the larve of 
Rhy phide. 
But to solve finally this ecien a comparative study of 
the adult stages of these Diptera had to be undertaken, and 
this was done by F. W. Edwards (1916, p. 115), who in his 
interesting paper “On the Systematic Position of the 
Genus Mycetobia, Mg.,” arrived at the following con- 
clusion :— 
‘* Mycetobia agrees with the Rhyphide and diverges from 
the } Mycetophilidee i in the possesston of a large gular plate, 
in the structure of the second palpal joint, in the position 
of the forking of the radial vein; the course of the cubital 
vein, and in the chitinous spermathece of the female. 
Since the venation of Mycetobia has been shown to be 
directly derivable from that of the Rhyphid genus Oldi- 
gaster, it is probable that any resemblances in this respect 
to the Mycetophilidie are due to convergent evolution, and 
not to relatiouslip. ‘The genus Mycetubia (and with it 
Mesochria, though not Ditomyia or Symmerus) must there- 
fore, on grounds of adult as well as larval structure, be 
trausferred from the Mycetophilidee to the Rhyphide.” 
Il. Ditomyia fasciata, Meig. 
The first indication of the habitat of this species we owe 
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