termination they open externally by orifices which appear to be cnidopores. These consist
of a fairly broad tube, which is narrowed by a constriction when it reaches the integuments
and forms outside the constriction a cup-shaped aperture. There are traces of similar
openings on the anterior margin of the foot; but it is unusual to find cnidocysts in this
position, and the structure of the organ is not clear. Abundant mucus glands are
scattered over the whole surface of the body, and the mucus can be seen under the
microscope in the act of exuding.
The hermaphrodite gland is large and fills all the posterior part of the body-cavity
with large yellowish packets. The anterior genital mass is. also well developed, but
hardened and not well preserved. No trace of armature was found, and the spermatotheca
appeared to be surrounded by the albumen gland.
HERO L ovin'.
G-. 0. Sars 1, p. 316, pi. xxviii. Bergh 32, pp. 309—314; id. 14, p. 699. Vayssiere 1, pp. 88—92.
Eliot 2, pp. 239 — 241.
Hero is a somewhat aberrant genus which in its general structure, especially the
buccal parts, approaches very near to the ^Eolididm blit differs from them in having
branched cerata, one pair of which is situated on the frontal margin before the rhinophores.
The known species are confined to the northern Atlantic and the Mediterranean. Bergh
gives four, but of these H. mediteiranea (Costa) appears to be founded on a misprint»
Costa in the Ann. del Mus. Zool. della R. Univ. di Napoli, 1866, p. 41,-includes in a list
of fauna “ Clcelia (a synonym of Hero) mediteiranea Nob. Grolfo di Napoli.” But on
p. 90 of the same publication under the heading “ Alcune correzioni ed aggiunzioni ” we
read “ pag. 41, verso 12, Clcelia leggi Tenellia.” The species is therefore not a Hero at
all, but the Tenellia mediterranea described by Costa in the same paper, which is perhaps
an Bmbletonia. Hero fimhiata is the Doris fimbriata of Yahl (Müller, Zoologia Danica,
1788, vol. iv, p. 22) described as Doris flavescens pedicellis dorsi arpice fimbriatis and
depicted on pi. cxxxviii, .fig. 2, which represents a yellow and pinkish animal with
slightly branched processes on the sides of the back and frontal veil. I t seems to me to
be a Tritonia or Marionia.
Two valid species are known: Hero formosa described below and recorded from the
northern Atlantic, and H. blanchardi Vayssiere from the Mediterranean. The latter is
yellowish, with red cerata; the frontal appendages are ramose, but those at the side of
the body are small and either undivided or simply bifid.
HERO FORMOSA L ov£n.
(Plate IY, figs. 1—4.)
This beautiful animal is not plentiful on the British coasts, but has been recorded
from several points such as St. Andrews, the Frith of Clyde, Northumberland, and
HERO FORMOSA. 121
Plymouth. Like many other Nudibranchs it has been observed to appear suddenly
in a locality and after a time to desert it altogether.
Hancock’s fig. 5 was drawn from an animal captured on a Pecten in twelve fathoms
of water at Millport. I t was active in captivity, but soon died, and was about 12 mm. long.
The living animal is of a transparent white with a more or less decided rosy tinge.
Down the centre of the back and on each side of the body runs a line of vivid opaque
white (three lines in all), and there are scattered flakes of the same colour on the body
and cerata. Large specimens. attain a length of nearly 20 mm., but the majority are
only half this size. The shape is slender and elegant.
The foot is slightly expanded in front, but neither grooved nor produced into
tentacular prolongations. I t is fairly broad, with thin expanded lateral margins. The
tail is short. The oral tentacles are unusually large, broad, and flat. They are curved
backwards, and may equally well be described as an oral veil with produced ends.' Immediately
above them is the first pair of cerata. Then come the rhinophores, two straight
simple pillars, slightly tapering but with no sheaths and no perfoliations. This latter
point is established by those who have seen the living animals, but in preserved specimens
the rhinophores often appear to be wrinkled and lamellated. Behind the rhinophores come
from three to six pairs of cerata. The structure of all of these (including those in front
of the rhinophores) is the same, but they differ in size and subdivision, the second or
third being the largest and those near the tail quite small, They appear to be formed
by a process of bifurcation repeated four or five times in the largest, but as the secondary
branches are close to the primary the arrangement often appears to be quadrifid. The
genital orifices are on the right hand side under the first of the cerata after the rhinophores
; the vent is under the second. The diverticula of the liver pass into the cerata
and extend right up to their tips. There are no cnidocysts.
The jaws are large but thin and transparent. The cutting edge bears a line of
irregular denticles and sometimes shows traces of two lines. The radula is triseriate and
consists of from forty-five to over sixty rows. The teeth are much as in Galvina. The
central tooth is strong and bears from two to four denticles placed rather irregularly on
either side of the median cusp, which is moderately long. The laterals consist of a
not very broad basal part from which rises a pointed but not hooked spine. The liver
consists of two principal trunks, which enter the stomach right and left and send off
diverticula into the cerata.
HERO FORMOSA var. ARBORESCENS.
Eliot 2, p. 239.
I have examined three specimens from St. Andrews which seem to constitute a
variety characterized by the great development and ramification of the cerata compared
to the size of the animals, which look like nearly circular pieces of branched seaweed.
The larger cerata are divided into four branches, each of which is subdivided four times,
and on the tip of each subdivision are four points, which, however, are not completely
16