bo 
92 Mr. Ernest Ewart Unwin on the 
The wings and legs of the fly can be made out, and the 
scarlet compound eyes are very conspicuous. 
THE FLY. 
The escape of the fly from the puparium is rendered 
possible by means of a special dorsal plate that opens like 
y 
pebidlap day 
AEN ities 
Fic. 8. 
Anterior end of puparium, showing the digitate spiracles. (x 50.) 
a lid (figs. 6 and 7). This plate can be observed upon 
an unopened puparium, for it is marked out by special 
lines of weakness along which the dehiscence takes place. 
On each side a longitudinal horizontal line extends from 
the anterior end of the puparium to the junction of the 
metathoracic and the Ist abdominal segments, where it 
Fic. 9. 
A single filament of the pupal spiracle, showing its epidermal investment. (x 200.) 
forks into a dorsal or ascending and a ventral or descend- 
ing branch. The ascending branch meets its fellow of the 
opposite side in the mid-dorsal line, but the descending 
one is very short and is not functional. Such a plate is 
a common contrivance in the Muscidae, although it is not 
always dorsal. Mr. T. H. Taylor informs me that it is 
