The back and wings are smooth and bear no cerata or appendages, but from the lower
part of the pericardium proceed fine, raised, ramified lines (usually issuing from three
main trunks) which mark tbe course of the blood-vessels. As a rule there is no ingluvies
bnccalis, and the teeth, which are shaped somewhat like daggers, are finely denticulate.
The liver, the hermaphrodite gland, and accessory genital glands are all elaborately ramified
within the wings, and do not form compact masses. The genitalia are not armed.
Pelseneer states that the kidney communicates with the pericardium through many
openings, but this is denied by some authorities.
Genus 1. Elysia Risso.
See Bergh 29, pp. 175—190; Vayssi&re 1, p. 137; Meyer and Möbius 1, pp. 7—10.
Anus antero-dorsal. Rhinophores auriform. Wings not crinkled or united behind
the head.
1. E. viridis Montagu.
(Pt. 8, PL VII,figs, 1, 2.)
[2. E. minuta Sars.
See Bergh 29, pp. 185—186, and references there given.
Coast of Norway. This very doubtful species was created by Sars in 1835, but in
1868 was recognized by him as not really distinct. Meyer and Möbius, Loven, and
Odhner (1907) regard it as merely a variety, but Bergh (1. c.) thinks it is a distinct
species characterized by (1) its dark colour, (2) teeth with blunt tips.]'
F amily XII. LIMAPONTIIDjE.
Minute slug-like animals without external gills, dorsal appendages, or pallial margin.
Anus dorsal and posterior. Mouthparts as in Elysia; teeth not denticulate. Stomach
small. Liver not much ramified, but divided into four main portions, two anterior and
two posterior. Hermaphrodite gland consisting of diffuse follicles as in Elysia. Penis
armed with a spine.
Genus 1. Limapontia J ohnston, 1836.
#|p= Pontolimax Creplin, 1848. Chalidis Quatrefages,
1844.
See Alder and Hancock 3 ; Meyer and Möbius 1, pp. 3—5 ; Bergh 30, pp. 205—209.
The head bears two crest-like ridges b u t no rhinophores or tentacles.
1. L. n ig ra J ohnston.1
? = L. capitata (O. F. Müller).
2. L. depressa A. & H.
(Pt. 8, PI. VII, figs. 6—8.)
1 As A. & H. (3, p. 403) dispute the identity of L. nigra with L. capitata, it seems safer to
retain the former name for the British species, though the latter has priority if the identity is accepted.
Genus 2. Acteonia Quatrefages.1
See Alder 1, pp. 30—31; Alder and Hancock 3, pp. 403—405.
Similar to Limapontia, but there is a slight ridge on either side of the back; the vent
• is not terminal but lies just behind the middle of the back, and the head bears two
ridges, which are produced into short, flat, ear-like tentacular processes.
1. A. corrugata A. & H.
Genus 3. Cenia A. & H.
Originally called Ictis, but re-named by Alder and Hancock on finding that Ictis was
already in use for a genus of Mammals.
See the same authorities as for Acteonia, and also Pelseneer, La condensation
embryogenique chez un Nudibranche, in Trav. zool. Wimereux, tome vii, pp. 513—520.
Similar to Acteonia except that the head bears two long linear tentacles. Pelseneer
has demonstrated that the larval development takes place entirely inside the egg and
that the animal issues in the adult form.
1. Cenia cocksi A. & H.
(Pt. 8, Pl. VII, figs. 10—11.)
. 1 It is doubtful if Cenia and Acteonia are really distinct. They are separated here merely
because Cenia has been shown to have an unusual larval development, whereas the early stages of
the dubious Acteonia are unknown.