249, Prof. L. C. Miall on Dicranota ; 
surround the alimentary canal. They represent the 
inner or splanchnic layer of the Chironomus larva. A 
pair of large cenocytes* occurs about the middle of the 
dorsal surface of each segment, just beneath the skin. 
There are also visible here and there some large 
spherical bodies lying in the ccelom, of which I can give 
no account. ‘The pericardial cells are described in con- 
nection with the heart. 
The Alimentary Canal of the Larva. 
The alimentary canal is a nearly straight tube of 
unequal diameter. It consists of a narrow cesophagus, 
a long and thick-walled stomach, and a narrow intestine. 
As usual, the cesophagus and intestine have a chitinous 
intima, which in each case is thrown into numerous and 
sharp longitudinal folds. The cesophagus extends from 
the mouth to the metathorax.+ It is wide where it joins 
the mouth, but quickly narrows and forms henceforth a 
tube of nearly uniform calibre. A dilation, which is 
variable in position and probably temporary in duration, 
is often to be seen in the lower part of the cesophagus. 
The chitinous lining of the funnel-shaped commence- 
ment of the cesophagus is set with many small backward- 
pointing prominences. Further back the chitinous 
lining becomes folded to such an extent as almost to 
obliterate the cavity. The muscles are annular and 
close-set. In good transverse sections a thin epithelial 
layer with nuclei can be made out. The cesophagus 
bulges for a short distance into the stomach, its chi- 
tinous lining being distinguished plainly from the villous 
epithelium which succeeds. ‘The stomach has a lemon- 
yellow colour. It extends from the metathorax to the 
9th segment. Its diameter, which much exceeds that 
of either cesophagus or intestine, is greatest in front, 
gradually diminishing to a constriction two-thirds of the 
way along, and then slightly enlarging again. The 
narrowest part of the tube has only half the diameter of 
the widest. The longitudinal muscles become external 
** Wielowiejski, Ueb. d. Blutgewebe d. Insekten, Zeits. f. Wiss. 
Zool., Bd. xliii. 
{+ The contractions and relaxations of the muscles of the head 
and cesophagus may draw the junction of the cesophagus and 
stomach backwards or forwards more than the length of one seg- 
ment from the normal position. 
