1929] 
Tracheal System of Blepharipa scutellata 
227 
Lepidoptera and Trichoptera, with a large dorsal system 
corresponding to the small dorsal system of the Trichoptera. 
Should a study of the tracheal systems of the more gener- 
alized Diptera show them to possess a system yet more 
similar to that found in the Trichoptera, it might be pos- 
sible to make a real homology of the various tracheal 
branches in the three orders. Blepharipa, and other musc- 
oids, apparently have but carried the specialization shown 
in Cecidomyia a few steps farther, and not really departed 
from the general type. 
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