356 Prof. Mialland Mr. R. Shelford on the Structure and 
small cross-connexion at the level of the pericardial 
diaphragm. As usual in submerged Diptera the branches 
of distribution are scanty, but ‘relatively large trachez 
pass to the long processes. (See p. 347.) 
The Phalacrocera larva can endure long abstinence 
from fresh air. We have kept them alive for a fortnight 
in a bottle absolutely full of water. In boiled water the 
larvee lived for five days, when the experiment was dis- 
continued. When access to fresh air is cut off the 
natural sluggishness of the larvee is increased, but no 
permanent injury results unless the experiment is greatly 
protracted. ‘he larva can live long out of water. 
5. The nervous system of the larva. 
The ganglia are the brain, the subcesophageal, three 
thoracic and eight abdominal (figs. 18a, 18b).. When the 
head is retracted, the brain and two, or even three, of the 
succeeding ganglia are enclosed within it; when it is 
extended to its utmost (about one-third ’ being then 
exposed) it contains only the brain and subcesophageal 
ganglion. 
According to Brauer’s peculiar nomenclature the 
Phalacrocera jarva has a true head, the Chirononus 
larva only a “ kiefer-kapsel.””? Yet his system requires 
that Chironomus should have the true head, and Phala- 
erocera the “ kiefer-kapsel.”’ It is becoming plain that 
Brauer’s classification of the Nemocera by larval 
characters is based upon an insufficient knowledge of 
the structure of the larve., 
The first abdominal ganglion is commonly found in 
its own segment, the last abdominal in segment 10. 
Between the brain and the first abdominal ganglia the 
connectives are double; in the abdomen they are 
single. 
A pair of small nerves issue from the brain, run along 
the dorsal vessel, and enter a pair of ganglia, which are 
closely applied to it (figs. 19, 20). ‘These are connected by 
short nerves with a frontal ganglion and a recurrent 
nerve. ‘lhe whole arrangement is very similar to what 
exists in the Chironomus larva, and the larva of the 
Crane-fly.* In the thoracic region nepaned nerves issue 
* aemond. Seen Coren. = x1., p. 204 (1875). 
