1929] 
Tracheal System of Blepharipa scutellata 
225 
the third abdominal segment. It runs diagonally forward 
and inward, crossing the second abdominal segment on the 
outside of the muscle layer (m,m,m, fig. 3) and sends a 
branch toward the middle of the body at about the middle 
of this segment ; then it continues across the first abdominal 
segment, in the body cavity, no longer attached to the body 
by muscles, and joins the side of the ganglionic mass. 
In the specimen examined, the fourth abdominal segment 
contained on the right side the trachea running outside of 
the muscle layer, but none that ran forward to the ganglia. 
However, the corresponding trachea on the left side sent a 
long branch forward across the third, second and first 
abdominal segments, to the ganglia. 
In the fifth segment a branch from the right ventral 
longitudinal trunk ran almost directly inward between the 
muscles and the body wall to nearly the mid ventral line of 
the body, where a long branch arose running forward, 
crossing the fourth, third, second and first abdominal seg- 
ments, in the body cavity, to the ganglion. None was present 
on the left side. This alternating right and left supply of 
tracheae to the central nervous system merits further in- 
vestigation. 
The tracheae, which ran between the muscles and the 
body wall apparently are homologous with the ventral 
transverse branches found in the lepidopterous and tri- 
chopterous larvae. In the larva of Pyrausta nubilalis Hubn. 
these tracheae form a transverse connection between the 
spiracles, except in the first abdominal segment. In the 
larvae of the Hydropsychidae studied by me these tracheae 
form transverse connections in the thorax but not in the 
abdomen, and in Blepharipa , they apparently do not form 
transverse connections. Snodgrass (1924) does not mention 
ventral commissures in Rhagoletis; and Williams (1910) 
does not mention them in Cecidomyia, but his figure (5 PI. 
6) apparently shows one in the metathorax. 
Trachese to the Alimentary Tract and Urinary Tubules. 
The alimentary tract (al figs. 2, 4) is supplied, in the 
anterior part of the body by branches springing from the 
