which no doubt accounts for the peculiar pulsation and contraction noticed by Alder and
Hancock in this part.
ELYSIA VIRIDIS (Montagu).
(Plate VII, figs. 1 and 2.)
Alder 1, pp. 31—32. Bergh 29, pp. 178—185. Meyer and Möbius 1, pp. 7—10. Pelseneer 1,
pp. 57—62.
The two drawings are by Alder. His description of the animal is as follows : “ Body
ovate-oblong, depressed, grass-green with bright azure or bluish-green spots of a metallic
lustre; tentacles ear-shaped, obtuse, dark green, frequently reflecting a purplish hue;
the darker colour is frequently continued over the head and on the upper and outer side
of the lateral lobes of the body, which are margined with white. A whitish space
surrounds each eye, and the elevated region of the heart is also pale; the lateral expansions
rise up in a curved line towards the middle of the back and diminish gradually to the tail;
their inside is paler than the out and beautifully veined with green from the hepatic
vessels1 appearing through. Length 075 mm. Habitat on Godium tomentosum, Zostera
manna, and other green seaweeds, in tidal pools, or occasionally in shallow water, especially
on the south and west coasts.
“ Var. olivacea.—Dark greenish, or purplish brown, spotted with blue and red dots,
the edges of the mantle and tips of the tentacles being white. Habitat, Lochmaddv
(MTntosh) and Kiel Bay (Meyer and Möbius).”
This form seems to be the Elysia minuta recognized by Bergh as a separate species.
Alder’s figures do not represent what I believe to be the commonest variety of
E. viridis, in which the wing-like expansions are considerably broader, the light dots less
conspicuous, and the inside of the wings is more markedly veined. But as far as the
shape goes, some specimens preserved at Plymouth justify the figure, for in the preserved
state they are 9 mm. and 11 mm. in length and only measure 2'5 mm. and 3 mm.
respectively from the foot to the margin of the wings.
The structure and anatomy of E. viridis have been described by Souleyet in ‘ Le
Voyage de la Bonite,’ by Pelseneer, by Bergh, and by Meyer and Möbius. The
specimens figured by the last-named authors belong to the variety olivacea.
The following points are extracted from these descriptions, in which, however, there
are some discrepancies : #
The nervous system consists of seven ganglia very clearly separate, round or some-
what oval in shape.
The buccal mass is relatively large, but there is no inglwvies buecalis. The radula
consists of about ten teeth in the ascending part, about twenty in the descending, and
about twenty more in the ascus or sack. They are of the form described as dagger,
shaped, but with cavities enabling them to fit into one another (see. Meyer and Möbius’s
1 It is probable that this expression is incorreot, and that Alder means the vein-like ridges which
radiate from the pericardial prominence.
plates); Each bears about eighty minute denticles on the lower edge. The salivary glands
are long and folliculate.
The stomach is small. The liver-system opens into it by one duct, which bifurcates
first right and left and then again into anterior and posterior branches. Both branches
are elaborately ramified and the ramifications extend among the genitalia and into the
wings and tentacles.
On the dorsal surface can be seen the rather large and prominent pericardium and a
system of thread-like ridges, which appear to be veins passing to the auricle through the
kidney. The kidney lies below, but also partially surrounds the pericardium, with which
it communicates by several (more than a dozen) orifices.1
The hermaphrodite gland is not a compact mass but a layer of diffuse follicles,
which is divided into a right and left portion and extends throughout the greater part of
the body. Its duct communicates with an oval body described as an ampulla. The
ramifications of the hermaphrodite gland are accompanied by the ramifications of two
other glands, one of which is described as a prpstate and the other as albuminiparous
(Pelseneer). But according to Bergh there is also a compact albumen and mucus gland.
There is one spermatotheca. The verge is unarmed; both it and a female orifice
(probably the oviduct) open behind the right rhinophore; another female orifice
(probably the vagina) lies dextro-dorsally in front of the pericardium.
LIMAPONTIA NIGRA J ohnston.
Alder 1, pp. 28—29. Alder and Hancock 3. Bergh 30, pp. 207-—209. Meyer and Möbius 1.
Pelseneer 1, pp. 62—64.
This genus and its species are not mentioned in the Monograph, but were dealt with
pretty fully by Alder and Hancock in the paper referred to above, which also contains
black and white figures. For a coloured figure of L. nigra see Meyer and Möbius’s
plate.
Alder’s description of the animal is as follows: “ Body smooth, rather depressed,
nearly linear when extended, but very contractile; the sides slightly overhanging the
feet; head truncated in front and flat at the sides, except where it is elevated into two
crest-like ridges, arched from behind forwards, on the sides of which posteriorly the eyes
are placed in a pale circular space which is prolonged into the crest. Vent subposterior.
The general colour is black, but sometimes individuals are found transparent and nearly
colourless, showing the greenish biliary organs through the skin. Length 0T4 mm.”
L. nigra is generally distributed over our coasts and is most commonly found on
Govfervse in rock pools between tide-marks. I t is gregarious and is said to emit a
peculiar sweet smell when bruised.
Little has been added to our knowledge of this minute form since Alder and
Hancock’s article, although it has been examined by Bergh, Meyer and Möbius, and
Pelseneer. The last named has published figures of the nervous system, genitalia, and
various sections.
1 So Pelseneer. Bat Hecht 1, pp. 645 ff, deuies this.