HANCOCKIA Gosse.
== Govia T rinchese.
Bergli (44, p. 1048) adopts Govia (Trinchese, 1886) as the name of this genus in
preference to Hancoclcia (Gosse, 1877), apparently on the ground that Gosse’s description
is inadequate. But though Gosse does not deal with the anatomy of the animal, his
description is amply sufficient for its identification. There can be no reasonable doubt
that his Hancoclcia eudactylota is the animal described below, and that it is generically and
perhaps specifically the same as the later Govia of Trinchese. The name is therefore
entitled to stand.
The genus appears to be rare, and is recorded from the south of England, Brest, and
the Mediterranean. Four described species are probably referable to i t : Hancoclcia
eudactylota Gosse; Govia rubra Trinchese; Govia viridis Trinchese; and Boto uncinata
Hesse. In the Journ. de Conchyl., 1872, p. 34, Hesse described under this name a Nudi-
branch captured at Brest, but Garstang seems to have proved that it is a Hancoclcia.
Whether there is really more than one species is a matter of some doubt. Perhaps
Trinchese’s two species are distinct, and perhaps his Govia viridis is identical with both
Boto uncinata and Hancoclcia eudactylota, so that the genus may be tabulated as follows: {1. Hancoclcia eudactylota Gosse, S. England.
2. H. uncinata Hesse, Brest.
3. H. vvt'idis Trinchese, Mediterranean.
4. H. rubra Trinchese, Mediterranean_
Hesse regarded his specimen as a Boto, and Bergh somewhat doubtfully refers the
genus to the Botonidse. It would seem to be intermediate between that family and
Lomanotus, but nearer to the latter. The narrow radula indicates affinity to Boto and the
true HSolids. The cerata show analogies to those of Boto, though they have not their
characteristic shape. But the perfoliations on the rhinophores, the processes on the oral
veil, and the manner in which the cerata arise from the dorsal margin recall the characters
of Lomanotus rather than of Boto.
HANCOCKIA EUDACTYLOTA Gosse.
Gosse, On Hancoclcia eudactylota, Ann. Mag. Nat. Hist., ser. 4, xx, 1877, pp. 316—319; Gamble,
On Two rare British Nudibranchs, Lomanotus genei and Hancoclcia eudactylota, ib., 6, ix,
1892, pp. 378—385; Trinchese, Richerche anatom, sul genere Govia, Mem. della R. accad.
delle sci. dell’ istituto di Bologna, ser. 5, vii, pp. 183—191,1886; Bergh 44, p. 1048, 1892,
sub voce Govia, Eliot 1, pp. 354—356 and figures.
Two specimens labelled “ Plymouth district, Sept. ’97 and ’98.” They are of much
the same size, one being rather more elongate than the other. Measurements in
millimetres:
Length. Breadth. Height.
(1) 7 1-2 2
(2) 6 1-5 2
The colour is greyish green, and the shape rather stiff and rectangular. The animals
are not very well preserved either externally or internally; but a small specimen subsequently
given me by Mr. Allen proved to be in better condition and was sectioned.
The foot is truncate in front; no groove is visible on the anterior margin; the tail is
not pointed behind, and is slightly bifid.
The oral veil is smooth in the middle and curves inwards, but the two sides are much
expanded and each bears fqur digits, of which the second from the inside is the longest.
The rhinophore sheaths, which are s6t on the dorsal margin, are about 1 mm. high and
5 mm. broad, straight, cylindrical, not expanded at the top, but divided into eight to ten
low lobes. The upper part of the rhinophores is a smooth column; at the base are a few
obliquely vertical perfoliations. From the rhinophore sheaths runs backwards a not very
distinct marginal ridge, on which are set five processes on the left side and four on the
right. The processes in the first pair are opposite one another. Then they gradually
become alternate. They bear lobes with a rather irregular outline, so that the whole
process looks like a short, thick branchial plume. The first pair have eight lobes, four on
each side, and are folded along the median line, the concave surface being turned outwards.
The second, third, and fourth pairs are similarly folded, but bear only seven
lobes, three on each side and one terminal. The fifth process (found on the left side only)
has five lobes and is irregular in shape. The genital orifices are close to one another, on
the flank of the body, between the rhinophores and the first process. The vent is between
the first and second processes, close to the dorsal margin.
The nervous system is yellowish. The ganglia are hard to separate, but as seen from
above appear to be as described by Trinchese. The cerebro-pleural ganglia are large and
triangular, showing no sign of division. The pedal ganglia, which are smaller, lie at their
side on a lower level. The buccal ganglia are large. The eyes are large and of an intense
bluish black.
The jaws bear a row of distinct but irregularly shaped denticles on the masticatory
process. Higher up on the jaw itself there seem to be numerous projections near the
edge. The radula resembles that of Galvina, and consists of thirty-one rows of three
teeth each. The median teeth are very strong and distinct, with four well-developed
denticles on either side of a large raised median cusp. The laterals are very thin and
hard to see, but are much as in Galvina, broad, but with a sharply pointed summit.
The animals being small and indifferently preserved, it was difficult to make out the
digestive system by ordinary dissection, and the following details are derived almost
entirely from the specimen which was sectioned. A fairly long oesophagus leads from the
buccal mass to the stomach and gives rise about midway to a curved diverticulum. The
stomach is roundish and not very large. From the top of it rises the intestine which
.sends out a tube to the anal papilla on the right. The anterior lower part of the stomach
is prolonged into two diverticula which supply the first pair of cerata and then run
straight forward, terminating in the anterior part of the foot. The termination is trifid.
Posteriorly the stomach gives rise to a long and fairly wide tube which extends to the
hinder part of the body and sends off branches to the cerata. These branches are at first
simple, but before they enter the cerata they divide into as many ramifications as there
are lobes to supply. These secondary ramifications arise at different levels. At their