Messrs. Haneock and Embleton on the Anatomy of Eolis. 183 
under the microscope to be composed of two distinct, though 
connate carpels; the ovules are few, horizontally attached, or 
somewhat pendulous from narrow axile placentz attached to the 
twofold dissepiment. These are characters that seem to corre- 
spond in great measure with the Bruniacee, with which the habit 
of Lonchostoma does not ill accord. These are merely hasty 
indications, as it would be foreign to the object of the present 
investigation to pursue such mquiries farther. 
XIX.—On the Anatomy of Eolis, a genus of Mollusks of the order 
Nudibranchiata. By Aupany Hancock and Dennis Em- 
BLETON, M.D. 
[Continued from vol. i. 2nd Series, p.-105.] 
[ With two Plates.) 
Nervous System. 
Tis is made up of central masses or ganglia united by com- 
missures, and of nerves. ‘The ganglia are five or six pairs, four 
of which are symmetrically arranged with regard to the median 
line, and together with their commissures surround the com- 
mencement of the cesophagus lying upon the upper and poste- 
rior surface of the buccal mass, vol. xv. Pl. V. fig. 16 4 and Pl. V. 
fig. 1 of present paper. Two pairs are supra-cesophageal and two 
infra-cesophageal. The former exceed the latter many times in 
size. The masses are of a pale yellowish flesh-colour, and appear 
to be filled with globular vesicles of various sizes. 
First, of the supra-cesophageal or cerebral ganglia, the median 
pair, Pl. V. fig. 1 a a, largest of all, are irregularly ovate, flattened 
above and below, and somewhat constricted about the middle as 
if composed of two parts; their anterior ends, which are the 
larger and truncated, are united across the median line by a short 
broad commissure. The second or lateral pair, 0, le rather 
behind the first and on the sides of the cesophagus; they are 
irregularly spheroidal, smaller than the first and flattened like 
them, and intimately connected to their external posterior mar- 
gin. ‘The two pairs of infra-cesophageal ganglia are of very un- 
equal size: the first or buccal, or larger pair, c ¢, are elliptical, 
their long diameters placed transversely one on each side of the 
median line, across which a short thick commissure unites their 
contiguous ends ; from the under surface of these, at their outer 
and anterior part, spring two short pedicles, supporting the 
second pair of ganglia, dd, the gastro-cesophageal, very small, 
not one-fourth the size of the last, but of the same form. In 
