that the optic nerve (y) is of considerable length. The nerve (J), supplying the reproductive
organs, comes off from a delicate collar, which has its two ends inserted apparently into the
branchial ganglia at their junction with the pedial, just where the visceral ganglion is
situated in Doris. This arrangement is the same as in Eolis. Ten or eleven pairs of nerves
have been ascertained to belong to the supra-cesophageal ganglia.
The infra-cesophageal ganglia are placed much further apart than usual, having the
median commissure very wide; the cords, too, that unite them to the cerebroid ganglia are
very long. The gastro-oesophageal (m, m,) are joined to the buccal ganglia (/, l,) by short
nerves, giving the former a pedunculated character: they send three pairs of nerves to the
oesophagus, the two principal of which supply that tube, one passing down it.
Portions of the sympathetic nervous system have been distinctly traced on the generative
organs,* and will in all probability be found on the other viscera.
The eye seems to be as well developed as in any of the nudibranchs; and from the high
development of the dorsal tentacles, and the crescentric enlargement of their base, olfaction
would appear to be extensively enjoyed. The auditory organ was not examined by us, but
M. Blanchard places it in the usual situation immediately behind the optic nerve.
The reproductive apparatus fills the greater portion of the body; and is provided with a
very large intromittent organ (fig. 9 6), which receives one end of a short, stout, tubular
testis (e) ; the other end of the testis tapers a little before it joins the oviduct. The ovary,
which fills much of the cavity of the body, is composed of two lobulated masses, one (fig. 1 o)
a little in advance of the other (p). The oviduct (fig. 9 d) is at first very slender; but as soon
as it reaches the mucus-gland, it greatly and suddenly increases in diameter (e), and as it
approaches, in a tortuous course, the anterior border of that organ, it as rapidly diminishes
almost to its original caliber. It then shortly after doubles upon itself (/), and is connected
with the testis; afterwards the oviduct is again a little dilated (p)} as it draws near to the
spermatheca (A), which is rather small. The duct (!) of the spermatheca is short and
constricted ; but, after its junction with the oviduct, is enlarged, and sends a short branch (m)
down into the mucus-gland. This duct, which must now be considered the vagina (n), passes
on in a straight line to the external opening between the male and the female outlets. In this
animal there is no accessory spermatheca; but the two dilated portions of the oviduct appear
amply sufficient to make up for the deficiency. Perhaps the enlargement of the oviduct at
its junction with the duct of the spermatheca may more particularly subserve the function of a
second receptacle. The mucus-gland (k, i), which is pyriform and somewhat compressed,
resembles the same organ in Doris more than that of Eolis.
* Traces of the sympathetic nervous system have been observed on the reproductive organs and on
the stomach of Eolis, since the description of that genus was drawn up.
EXPLANATION OF THE PLATE.
Fig. 1. General view of the viscera of Antiopa cristata, the dorsal skin having been removed:
a, buccal organ; b, oesophagus; c, stomach; d, intestine; e, anal nipple; f f f f ,
anterior hepatic trunk-tubes; g, g, g, branches from the median hepatic trunk-tube ;
A, A, net-work of tubes in connexion with the ramuscules of the hepatic system; i, a
dense glandular mass surrounding the termination of the intestine, apparently in
connexion with the hepatic system; j , ventricle of the heart; A, auricle;. the oval
shadowing marks the extent of the pericardium; l, small vesicle or portal heart,
opening through the floor of the pericardium; m, portions of the male generative
organ; n, mucus-gland in connexion with the female channel; o, anterior lobe of ovary;
p, posterior lobe of the same; q, supra-cesophageal ganglia, with various nerves passing
from them.
2. Digestive apparatus of Antiopa cristata, with the hepatic glands of the papilla} and the
net-work of hepatic tubes removed: a, buccal organ; b, oesophagus; c, stomach;
d, glandular portion of the same; e, intestine; f anal nipple; g, g, anterior branches
of the anterior hepatic trunk-tube; A, A, posterior branches of the same; i, median
hepatic trunk-tube giving branches to the papillae of either side on the posterior portion
of the body; j , j , ramuscules leading to the glands of the papillae.
3. Under or front view of the jaws of Antiopa cristata: a, anterior plate with denticulated
cutting edge; b, plain inner cutting edge.
4. A single jaw of the same, viewed with the cutting edges in front: a, denticulated cutting
edge; A, plain inner cutting edge; c, point of articulation.
5. Tongue of A. cristata: a, exposed portion exhibiting rows of spines; b, tubular portion
of the same.
6. Central portion of two rows of lingual spines: a, central spine; b, lateral spines.
7. A single lateral spine a little more enlarged.
8. Hepatic gland, removed from- papilla; a, terminal folliculated portion; b, stem or duct.
9. Generative organs spread out, the ovary having been removed: a, channel of the penis
leading to external orifice; b, retracted penis; c, testis; d, constricted portion of the
oviduct, as it leaves the ovary; e, dilated portion of the same; ƒ, the point where it communicates
with the testis; g, second dilatation of the oviduct; A, semi-pellucid portion
of the mucus-gland in connexion with the female channel; i, opaque portion of the
same; j , female channel leading to external orifice; k, spermatheca; l, duct of the
same; m, branch of the duct leading into the mucus-gland near to the female channel;
n, external channel or vagina leading to the spermatheca.
10. Cerebral or cephalic ganglia: a, a, cerebroid ganglia; b, b, branchial ganglia; c, c, pedial
ganglia; d, d, olfactory ganglia; <?, inner portion of the olfactory nerve, supplying the
crest at the base of the tentacles; nerves from the cerebroid ganglia, supplying
the lips and channel of the mouth; g, optic nerve and eye; h', nerve to side of body;
A, A, pedial nerves; i, branchial nerve, supplying the sides of the back at the base of
the papillse; j , genital nerve, given off from a delicate nervous collar; k, great
oesophageal collar; l, buccal ganglia; m, gastro-oesophageal ganglia, each giving off
three nerves, which pass to the oesophagus.