14 Psyche {February 
windows into the interior. Here we may see the rhythmic pulsa- 
tions of the long heart. 
Notched Processes of the Thorax. On the prothorax are two 
notched projections just over the respiratory siphons. In one 
specimen, on the second day after the third molting, an opening 
was plainly visible at the base of both the first and the second 
hairs on each side of the thorax (fig. 19). The delicate two- 
lobed structure had developed between the hairs and the openings. 
After a time the two hairs fell off, the inner one falling several 
hours earlier than the outer. This left the third hair, which is 
branched, with the two delicate processes and the openings close 
tothem. Each opening is rimmed with several little ridges placed 
parallel to the hairs. The transparent lobes would seem to pro- 
tect the openings. Within, each leads into one of the two tubes 
before described, and which must lead into the tracheal system, 
although their connection with the trachez is not evident from 
the outside. The openings are situated just where the thorax is 
applied to the surface film, and are related to the respiratory 
siphons of the papa. 
The Change to the Pupa. After the tuft of branched hairs has 
appeared on the first segment of the abdomen, we may look for 
the change to the pupa before many hours. The thorax will 
soon show a series of transparent spots, suggesting the areas in 
the abdominal segments, and due, doubtless, to the segmented 
structure of the thorax. The throbbing heart becomes plainly 
visible along the mid-dorsal line. The following record of the 
time was kept as one specimen changed: (8.30 p. M.) The larva 
was perfectly quiet for a long time, with the antennz and hairs 
of the head drawn up close. The body expands frequently and the 
head is drawn in somewhat. The hairs on the thorax lie limp, 
pointing downward. The sides of the metathorax become some- 
what sunken, as if parts beneath had changed position, (9.40 P. M.) 
Tiny dots on the rims of the respiratory siphons show through the 
transparent integument. (These may be identified later on the 
edges of the siphons of the pupa.) There is a rowing motion of 
the hairs of the whole body, and a regular pushing with the pos- 
terior end against the sides of the watch glass. In the abdomen, 
fine ridges or wrinkles appear across the segments, between the 
palmate hairs. (10.15 p. M.) The segments of the abdomen begin 
