Mar., 1912.] 
Life- Histories of Syrphidae III. 
485 
is evident; the puparium is not strongly elevated posteriorly, 
being convexly depressed gradually from about the middle. From 
in front the puparium appears nearly circular in outline, very 
slightly flattened ventrally. 
The posterior breathing appendage (Fig. 55, a) is as in the larva 
but entirely black, the segment inflated beneath it. The anterior 
spiracles remain visible externally, antero-dorsal to the tip of the 
mouth-parts, with parts of the tracheae leading from them visible 
flattened against the inside of the puparium (Fig. 51, a). The 
larval mouth parts also become flattened against the puparium on 
their right or left side. (Fig. 51, b, c, d). At first the pupa 
shrinks away from these parts but later as the adult head develops 
fills up the space again. A line of weakness develops in the 
puparium running from the apex of the mouth-parts dorsally 
between segments 6 and 7. The expanse of the ventral part of 
the face then forces off a circular operculum along this line for the 
emergence of the adult. Posteriorly part of the large tracheal 
trunks remain in connection with the spiracles. 
Color of the puparium, empty: pale browm, transparent; with 
pupa enclosed: variable, darker brown, strongly tinted with 
salmon. A day or two before emergence the prominent colors of 
the adult become plainly visible. 
Pupa. 
The coarctate pupa (Fig. 54) is covered with a delicate trans- 
parent membrane (a) with pockets encasing the developing legs, 
wings, etc. The changes visible externally are gradually produced 
and give little indication of the radical internal histolysis and 
histogenesis. 
At an early stage (Fig. 53) when the dorsal part of the abdomen 
is simply a mass of fatty granules as in the larva with the 
position of the dorsal blood vessel indicated and the head and 
thorax irregular, angular masses; the legs, or the cases enclosing 
them (Fig. 53, a, b , c ) have already reached their full size; although 
there is no vestiture developed on them and their outline and 
segmentation are indefinite. The wing-pads, also, (d), are as 
large as they will become before emergence but show no signs of 
the venation which is prominent at a later stage. They are folded 
ventrally about the sides of the body. 
The mouth-parts are visible as long, cylindrical, fleshy buds ( e ). 
The eyes are not indicated externally except as irregular oval 
areas about half the size of the adult eye antero-dorsal in position, 
bounded by a slightly elevated ridge. 
A considerably later stage show's the abdomen still cylindrical 
without color and with only a little vestiture, the segments faintly 
indicated by constrictions, the fatty granules gone. The head is 
