272 Prof. L. C. Miall and Mr. T. H. Taylor on the 
on its inner surface. By appropriate methods the thin 
larval cuticle can be separated from the later calcareous 
addition. The body of the puparium (fig. 10) is rusty in 
colour, with a smooth shining surface, and flattened dorso- 
ventrally. The larval head has been completely retracted, 
and the fore-part of the prothorax, sharing in the move- 
ment of retraction, forms a funnel-shaped depression on 
the front part of the ventral surface of the puparium. 
This depression is partly filled up with a waxy secretion, 
which appears at the mouth just before the movements of 
the larva cease. The spiracles, anterior and posterior, are 
now black and strongly chitinised. The fly escapes from 
the puparium by a hinged plate (fig. 11) which very 
nearly coincides in position and extent with that special 
part of the general blister which we have called the 
lies Tle 
Hinged plate of puparium. The oral and endocranial 
plates of the larva remain attached to the inner 
surface. (x 45.) 
“pupal blister.” When the fly is ready to emerge the 
plate 1s raised in front and pushed back (fig. 12), bringing 
with it the cuticle of the blister. The rupture is effected 
by the alternate swelling and contraction of the frontal 
sac of the fly, which is very distensible and roughened 
on the outer surface with numerous fine denticles. The 
ventral surface of the fly appears first with the legs. The 
wings are crumpled when they are withdrawn from their 
sheaths, but soon expand. 
Empty pupal cases in blistered holly-leaves can easily 
be identified by the raised hinged plate. Sometimes, 
instead of the raised plate, one finds in the pupal blister 
a small circular aperture; this marks the place through 
which a parasitic ichneumon has escaped, and it is interest- 
ing to notice that the ichneumon quits the puparium and 
