The radula is short and does not consist of more than twenty teeth, besides those in
the ascns. The teeth are spoon-shaped and not denticulate. Meyer and Mobius’s plate
represents them clearly. The oesophagus is. long, the stomach small. The liver forms
two slightly ramified canals, extending from the buccal mass to nearly the end of the
body on either side and united above the stomach by a transverse bar. In front of the
buccal mass are small lobed salivary (or ptyaline) glands. The intestine is short and
runs from the left-hand side of the stomach to the anal papilla which is medio-dorsal, a
little behind the centre of the body.
There are no branchiae of any sort, respiration being performed by the whole
surface of the skin. The heart is medio-dorsal and of the usual structure. The kidney,
which is small and not ramified, lies behind it. I t does not open into the pericardium by
multiple orifices.
The genitalia are much as in Elysia. The hermaphrodite gland is flocculent and
diffused throughout the hinder part of the body. The tubular “ albuminiparous ” gland
is also ramified, but the prostate is compact. There is a single spherical spermatotheca
and three external orifices.
LIMAPONTIA DEPRESSA A. & H.
(Plate VII, figs. 7—9.)
Alder 1, p. 29. Alder and Hancock 3.
Alder’s description is as follows: “ Body oblong-ovate, depressed, swelling behind
the centre and terminating in a blunt point posteriorly; black, generally with minute
yellowish-white spots or freckles. Head rounded in front and slightly angulated at the
sides; the lateral crests less elevated than in L. nigra, with the eyes situated in a white
oblong area at each side of them. Vent placed in a depression at the posterior extremity
of the body. Length 0-4 mm. Habitat: On Conferva in brackish water; near Sunderland
and Swansea.”
The species appears not to have been found since the time of Alder and Hancock.
I t differs from L. nigra in being larger, flatter, and wider, and almost shows a commencement
of wing-like expansions as in Elysia. Owing to this greater breadth there is room
for a much more considerable ramification of the liver, which can be seen through the
sides in fig. 8. The vent is almost terminal, and placed in a groove at the end of the
dorsal surface.
ACTEONIA CORRUGATA A. & H.
Alder 1, p. 30. Alder & Hancock 3, p. 404.
Alder’s description is as follows : “ Body nearly linear, rather short and stout,
regularly wrinkled in a longitudinal direction ; black, excepting the carina and tail, which
are whitish. Head carinated at sides, each carina being produced into a short, flat,
whitish tentacular process. Eyes placed in circular white spots behind the carinae.
There is a slightly raised ridge on each side of the back, in the region of the vent.
Length 0T2 mm. Habitat: rare; found by Mr. Cocks at Falmouth'feeding upon Conferva
glaucescens in company with Limapontia nigra.”
I have not seen this specie^ alive, but have examined a preserved specimen purporting
to belong to it and found at Plymouth.1 Except that it has become uniformly
black and shows no white markings it corresponds fairly well with the above description.
The body is wrinkled longitudinally and also bears a low ridge on either side of the
visceral hump. There are two other small ridges on the head, each of which is produced
into a short tentacle. The radula is transparent and composed of thirteen teeth, six in
the ascending and seven in the descending part. There are twenty in the heap. They
are of the spoon-like shape common in the family, but in all the teeth there is a small
indentation on either side of the end of the spoon, producing a small denticle. The
verge is armed with a short curved spine. The specimen was about 4 mm. long and too
hardened for anatomical examination, but the liver and hermaphrodite gland seemed to
be as in Limapontia.
CENIA COCKSI A. & H.
(Plate VII, figs. 10 and 11.)
Alder 1, pp. 30—31. Alder and Hancock 3, p. 404. Pelseneer, La condensation embryogenique
chez un Nudibranche, in Trav. Zool. Wimereux, tome vii, pp. 513—520.
Mr. Elmhirst has kindly sent me from Millport a fine specimen of this Nudibranch
which appears not to be common on our coasts. I t is active in its movements when in
the water, but frequently crawls outside and reposes about an inch above the water. It
lived about ten days in confinement, apparently in perfect health and vigour, until it
was killed.
When crawling it is about 6 mm. long and 2 mm. broad, but frequently contracts
into a spherical shape with a diameter of about 3’5 mm. The rhinophores are thin and
distinct, about 1 mm. long. The pericardium is moderately prominent in the middle of
the back. No orifices are visible, but the verge projects just behind the right tentacle.
The dorsal spots are not raised, and except the rhinophores there are no appendages or
prominences of any kind,2 but when the animal moves wave-like ridges often pass
temporarily over the skin.
The body-colour is dark purplish brown, and under a lens is seen to be composed of
numerous minute spots and granules. In the centre of the back is a yellow spot, and on
either side are four others. The rhinophores are yellow, and yellow lines, which when
the animal is extended form ridges, run from the rhinophores to the front of the head.
The sole also is clear transparent yellow and allows the intestines to be seen. The
1 A second living specimen sent to me from Plymouth while this work was going through the
press seems to me to be really Cenia cocksi, and I do not feel sure that I have ever examined a
true Acteonia.
8 But Alder (Z. c., p. 31) says: “ On each side of the back near the vent is a slight ridge.” I
could not see it.