182 LIVERPOOL BIOLOGICAL SOCIETY. 
each segment of the abdomen, 1.e. one to each ala, and each 
mass has a number of nuclei (2 or 3 up to 8 or 10), though 
the cell-boundaries are not to be made out clearly. The 
protoplasm of the cells is markedly spongy, and contains 
numerous granules which stain deeply with carmine, and 
which Kowalevsky regards as excretory products. 
The five Malpighian ceca have their blind ends lying 
free in the seventh or eighth segment: from this point - 
each runs forwards to the anterior end of segment V., and 
then turns back to open into the commencement of the 
intestine. Hach consists of two rows of very large cells 
which have an intense white colour due to minute granules 
of excretory matter. These organs undergo no marked 
change during the pupal period. 
The respiratory system of the larva is, according to 
Raschke (4), three-fold. The rectum and the four gills 
around the anus have already been described. The gills 
are shed with the larval cuticle. The chief respiratory 
system consists, however, of trachez, the two very large 
main trunks of which run the whole length of the body 
and open to the exterior at the tip of the siphon. These 
are very large, and serve both as a store for air and as a 
float. They are connected by imperforate branches with 
the external cuticle at points on the sides of the body 
corresponding to stigmata. During larval life a new cuti- 
cular lining (‘‘ intima’’) 1s formed around the old one, and 
the old one is shed with the exuvie. 
The stigmata of the pupa through which the larval 
tracheal intima is drawn out immediately close, and the 
new intima of the branches connecting them with the 
main trunks collapses, so that the stigmata are function- 
less. One pair, those in the first segment of the abdomen, 
form an exception: they remain wide open, and the intima 
just within the stigmata is beset with numerous small 
