234 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
Hyraenoptera, where it is well developed. We have been tillable to find 
It as yet in the brain of myriopods or of the spider. In the locust each 
body is more or less rounded and rudely saucer-like rather than cup- 
like, with the rim very thick ; the hollow of the cup, if it be hollow, is 
small in proportion to the thickness of the saucer-like cup. The diam- 
eter of a calyx is about yfo. The anterior edge reaches to the front 
edge of each hemisphere of the brain, but does not extend to the baek 
part of the brain. The relations in a vertical, i. c, longitudinal section 
of the mushroom body to the rest of the brain are seen in (PI. X, Fig. 
8 a). It thus appears that the double stalk is situated near the center 
of the brain, and that the cap projects far forward, but posteriorly does 
not extend behind the an tennal lobes or the commissures. In section 18 
(Fig. 4) the calices are seen to be double, the outer (0. cal.) attached to 
the cauliculus (cati.) and the inner arising from the peduncle. Fig. 8 a 
gives an idea of the two calices and their mode of attachment to the 
stalk. The peduncle (if we interpret that division of the stalk aright) 
subdivides, sending a thick bundle of fibers to each calyx, ending ab- 
ruptly in the hollow of the calyx. The substance of the calices is finely 
granular, with some coarse granules, and apparently short scattered 
irregular fibers. The structure of the calices of the locust appears to 
be more homogeneous than that of the cockroach, judging by our sec- 
tions of the latter. Owing to different treatment by reagents the dark 
masses described by Newton as existing in the cockroach were not so 
clearly shown in my sections (tooo mcn thick) as in those made by Mr. 
Newton. The substance of the calices when examined under a power 
of 725 diameters is much the same both in the cockroach and the locust, 
the dark bodies not appearing in either. The form of the calices is very 
different in the cockroach, the calices being truly cup-like, the disk being 
deeply folded, and the edges of each cup being thin compared with those 
of the locust. 
The optic lobes. — As seen in section 19 (PI. XI, Fig. 1 op. I.) these 
bodies are larger than the antennal lobes, and consist of numerous 
irregular small bundles of fibers besides those composing the optic 
nerve, the interspaces being filled with fine granular nerve substance. 
The optic nerve is much larger at the outer edge of the lobe before pass- 
ing into the optic ganglion, the fibers still being immersed in the finely 
granular nervous substance. 
The optic ganglion. — This is situated at the back of the brain, and is 
a large rounded mass of white fine granular nervous matter, enveloped 
in very numerous but small ganglion cells, which stain dark red by car- 
mine, the granular matter remaining unstained by the picrocarmine. 
The granular or white portion is subdivided into three rudely lens- 
shaped masses (see PI. XV, Fig. 1), the one nearest the eye being much 
the largest. The structure of the optic ganglion is substantially as 
described by Newton, as seen in his description and our preparations. 
A farther description is reserved for our account of the eye, which we 
hope to give in the next report. 
