the vent on the median line about two thirds down the back. They, like the tentacles, are
non-retractile and are without lateral appendages. The foot is rather large, rounded in front,
and produced into a point behind. The generative organs have a single aperture, which is
situated on the right side, a little behind the dorsal tentacles.
In its internal structure Goniodoris is not very dissimilar from Boris. The mouth opens
on the inferior surface of the head, whence a short channel leads into the buccal organ
(PI. 17, fig. 1 a), which, though not very large, is muscular, and has appended to its upper
surface a spherical gizzard (5), with radiating muscles, similar to that in Boris bilamellata and
others. The tongue is narrow, and composed of numerous rows of four plates each; the two
plates next the median line bearing large curved spines with denticulated margins in G. nodosa:
in G. castanea the margins are plain. There is no central spine or plate. Not more than
half of the tongue is brought into action at a time, the posterior portion being tubular and
placed in a sheath which extends from behind the buccal organ: here the spines are
generated, as in Boris. The buccal lip is provided with a prehensile collar (fig. 2 a),
interrupted above, and crowded with numerous, minute, bifid spines (fig. 3).
The oesophagus (fig. 1 d)3 which is rather long and slender, passes from the upper aspect
of the buccal organ just behind the gizzard, and, after passing through the nervous collar, is
slightly dilated in G. nodosa, but in G. castanea is of equal caliber throughout. Two short,
folliculated salivary glands (c, c) open into the buccal cavity, one on each side of the
oesophagus. The stomach (e) is small, of an irregular form, situated in a shallow cleft in the
anterior border of the liver. The oesophagus enters it in front, and the intestine (y), which
is a simple tube of no great diameter, passes off from the upper aspect, and crossing the
upper surface of the liver, dips down on tbe right side on its way to the anal nipple, situated
in the centre of the branchial circle. The biliary secretion enters the digestive cavity by two
or three large orifices near to the oesophageal opening. No pancreatic organ has been
observed. The liver ( / ) is a large oval mass, filling up the posterior portion of the visceral
cavity, and having a shallow cleft in front for the reception of the stomach; it is granular and
of the usual dark brown colour.
The reproductive organs are constructed on the same plan as in Boris, but show some
interesting modifications of the component parts. The testis is divided into three well-marked
portions;—next the intromittent organ (h), it is stout and tubular (t) ; some distance backwards
it suddenly contracts and becomes minute and duct-like (i"); this second portion leads
to one extremity of a fusiform, glandular body («"), which is doubled upon itself, and has the
other extremity opening into the oviduct. The second portion seems deficient in G. castanea.
The gland-like portion of the testis has some similarity to that described in Boris cocdnea.
The ovary (k,Jc) is spread over the upper surface of the liver, and presents a decidedly
dendritic structure, crowded exteriorly with numerous ovigerous follicles. The oviduct is at
first very slender { j ), but, suddenly dilating, becomes excessively wide, and as it advances to
the anterior margin of the mucus-gland it is reduced at once to its original caliber before
receiving the extremity of the testis; it shortly afterwards receives the duct (o) from the
spermatbecae and thence dips down into the mucus-gland. The vaginal tube (m), is rather
wide and long ; it is doubled upon itself, and before reaching the spermatheca is much
attenuated. There are two spermathecae, one very large (n), the other small (p), the former is
long and pyriform, the latter elliptical. The mucus-gland (l) does not differ materially from
that of Boris. In G. castanea the vaginal tube is very much shorter than in G. nodosa, and
can scarcely be said to be doubled upon itself; the large spermatheca is elliptical, and is also
much smaller than in the other species.
The vascular and respiratory system, so far as we have been able to ascertain, are in the
same condition as in Boris. The heart rests on the upper surface of the liver, and is contained
in a well-defined pericardium ($'). The auricle (s), receives the blood by two lateral vessels
(t, t), from the skin, and by a posterior median one (u), from the gills; that is, in this way it
is returned from the general system and from the liver mass: it is then passed into the
ventricle (r), and is distributed to the various organs by arteries, which branch from a large
trunk that issues, in the usual manner, from the anterior apex of the propelling organ. The
portal heart (w), is distinctly seen lying below the pericardium, into which it opens, and its
vascular trunk can be traced into the renal organ. From these facts, it is evident that here,
as in Boris, the blood is returned to the heart only partially aerated, and that the systemic
circulation is twofold,—general and partial; the latter comprising a portal circulation.
The renal organ (y) covers the greater portion of the upper surface of the liver, lying
immediately above the ovary, and resembles the same organ in Borispilosa. Its margins are
somewhat sinuous, and the inner surface of the circumscribing membrane is richly supplied
with a vascular net-work, with which the twigs from the trunk given off by the portal heart
go to inosculate. The renal orifice opens externally, close to the base of the anal nipple, in
front and to the right side.
The nervous system is highly concentrated in this genus. There are four principal
oesophageal ganglia, and four buccal; of the former, two are above, and two at the side of the
alimentary tube; those above are broadly ovate, with their sharper ends placed towards the
median line, across which they are united. These ganglionic masses (fig. 4 a, a) are
composed of the cerebroid and branchial ganglia, completely fused; and give off, from the
upper surface of the frontal margin two large nerves (1), which go to the dorsal tentacles:
these have attached to them, at their origin, the olfactory ganglia (c,c), which are round, and
almost as large as the buccal ganglia. Three other pairs of nerves (2,3,4) pass from the
under surface in front, and go to the channel of the mouth and lips; the largest of these (3)
gives a stout branch to the oral tentacles. From behind,—the branchial portion,— a larger
nerve (6) is given off from each mass, and goes to supply the dorsal skin or mantle.
The pedial or lateral ganglia (6, 6) are closely united to the under surface of the upper
pair, and are joined below the oesophagus by a short, stout, commissural cord {y), the great
oesophageal collar, composed of two filaments—one being much finer than the other. These
ganglia furnish each two or three nerves to the foot.
A small visceral ganglion (d) is attached to the under surface of the right upper
ganglionic mass behind; consequently to the branchial portion of it. It gives off two or
three nerves (11,12), which go to the viscera. A commissural cord {i), also comes off from this
ganglion, and passing under the alimentary tube, in conjunction with the great oesophageal or
pedial collar, goes to the branchial portion of the opposite ganglion. There is also another
nerve from the oesophageal ganglia; this (7) comes from the right upper ganglion, close to
the visceral, and may possibly belong to it. This nerve goes to one or two small ganglia (y),
on the root of the penis.
The eyes, which are as well developed as in Boris, are fixed on small roundish ganglia