240 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
First pupal stage of Caloptenus spretus. — My sections are too imperfect 
to describe, but the form of the bruin is closely like that of the next stage. 
Second or last pupal stage of Caloptenus spretus. — A number (14) of very 
successful sections made by Mr. Mason from one head give an excellent 
opportunity for studying the head of the locust in this stage, just be- 
fore becoming Hedged (see first Report, PI. I, Fig. 5). Of these sections, 
Nos. 8 aud 9 pass through the calices and oesophageal lobes, but do not 
reach the central body. Section 10 (Fig. 1 of PL XIV) passes through 
the central body, which is of an inch in thickness, the section itself 
being of the same thickness. In the optic ganglion the section passes 
through the front of it, but two lenticular masses appear. The trabe- 
cular are as in the adult, and the superior and inferior intra-trabecular 
nerves are clearly seen to pass into the center of each trabecula just as 
in the adult. On the left side the origin of the cauliculus and peduncle 
is clearly seen, under a power of 225 and of 400 diameters, the relation 
of parts being exactly as in the adult (see PI. X, Fig. 3). The base of 
the two divisions of the double stalk arise suddenly, as if inserted into 
or resting simply upon, rather than arising from, the trabeculse ; the 
bases of the cauliculus and peduncle being in the same line with the 
base of the center of the upper division of the central body. It ap- 
pears as if a few nerve fibers passed under the base of the stalk between 
it and the trabecula ; at any rate, I have been unable to observe either 
in the pupa or larva or adult, among a number of preparations, any con- 
tinuity between the trabecular and the double stalk. 
In this section the curving of the double stalk backwards and the 
passage in front of this double column is to be clearly seen, and is just 
as we have described it from similar sections of the adult brain (Fig. 
3 of PI. X). The ball like masses in the oesophageal commissures are 
as distinctly shown as in the adult. 
Section 11 passes behind the central body, not showing it nor the 
basal part of the double stalk of the mushroom body. This section, and 
those behind it, show well the structure of the optic ganglion. In sec- 
tion 11 the three lenticular bodies clearly appear. 
The main, and almost the only, difference between the second pupa 
and the adult appears to be in the degree of development of the ceutral 
body. In the second pupa (PI. XIV, Fig. 3) it is rather more elementary 
than in the adult, the upper and lower series of unicellular bodies being 
a little shorter and rounder, nearer their primitive condition, aud the 
septa between them are plainly fibrous. Their contents are as finely 
granular as the adjoining parts of the body. 
Section 11 is instructive as showing a bundle of directly ascending 
and obliquely ascending fibers from the back part of the trabecula, of 
which a portion is contained in the section. Two large bundles enter 
the commissural lobes, one from above and one from the inner side under 
the central body, the bundle from above passing down into the lobe from 
around the upper side of the trabecula. From this fact we should infer 
