376 The Brain of the Embryo and Young Locust. [ May, 
Third Larval Stage of Caloptenus bivittatus —In the third larval 
condition of another species, the common Caloptenus bivittatus of 
our gardens, the different parts of the brain have attained nearly 
the same structure and proportions as in the adult. PI. x1u, Fig. 
1, of the second report represents a section passing through the 
front of the brain, and also the lateral ocelli and the right eye. 
The ganglion cells surrounding and filling the calices are smaller 
and more crowded than elsewhere. The mushroom bodies are 
now formed, though the trabeculz are not to be seen in our sec- 
tion, but the entire double stalk and calices are very clearly seen. 
The fibers from the stalk are observed to extend along the inner 
edge of each calyx and to suddenly stop just beyond the middle. 
The granular calices contain slight irregularities and sinuous 
lines, as shown in Fig. 2, 2. ca/., 0 ca., but to what these appeat- 
ances are due it is difficult to say; there are also a few scattered 
large granules. As the section passes through the front of the 
brain, where the hemispheres are separated by the frontal furrow, 
the lobes are not well marked, but the substance is made up of it- 
regular intercrossing bundles of fibers, with the interspaces filled 
with granulated matter. In Fig. 3 the regular saucer-like form of 
the calyx is well shown. Fig. 2 is an enlarged view of the right 
side of Fig. 1, and at this stage large important bundles of fibers 
are seen passing into the optic, antennal, and commissural lobes. 
First Pupal Stage of Caloptenus spretus.—My sections are too 
imperfect to describe, but the form of the brain is closely like 
that of the next stage. 
Second or last Pupal Stage of Caloptenus spretus—A numbert 
(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 before becoming fledged (see first Report, 
Pl. 1, Fig. 5). Of these sections, Nos. 8 and g pass through the 
calices and cesophageal lobes, but do not reach the central body. 
Section 10 (Fig. 1, of Pl. 1v) passes through the central body, 
which is sts 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 trabeculz 
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 
