122 HERO FORMOSA VAR. ARBORESCENS.
developed in all cases. There is no trace of the usual white lines and spots. They may
have disappeared owing to the action of the preserving fluid, but they usually remain in
preserved specimens.
The central teeth of these specimens had consistently three strong denticles on
either side, the first pair nearly as large as the central cusp.
JANOLUS HYALINUS (A. & H.).
= Antiopa hyalina A. & H.
(Plate V, figs, 4—7.)
Bergh 47, pp. 7—11.
The figures of this animal given by Alder and Hancock, plate 44, are not good, but
those now published will, it is hoped,.be found more satisfactory.
The notes on the drawing merely say “ Mr. Byerly : 29 Aug., 1854. Animal active,
moves rapidly.” •
The species has been described by Bergh (Z. c.) and referred by him to the genus
Janolus. This genus has most of the external characters of Antiopella (= Janus, =
Antiopa), but is distinguished by its huge undenticulate jaws, which form the sides of the
buccal mass. Several species have a very broad foot with an expanded margin, but this
character is not present in all. Janolus hyalinus is also nearly allied to Proctonotus
(which has somewhat similar jaws), inasmuch as it has cerata studded with knobs, and
the two genera are only distinguished by the absence in Proctonotus of a crest between
the rhinophores.
I have not had an opportunity of seeing Janolus hyalinus alive, but have examined
two preserved specimens captured at Plymouth, one 8 mm. long, the other only 4*3 mm.
They agree as .to external characters with Alder and Hancock’s description. The
colour is yellowish, with traces of lighter and darker mottlings. The cerata are crowded
and irregularly set. There are generally four to five in a transverse row. The innermost
are the largest and about 5 mm. high; they decrease in size outwards, and the
outermost are mere tubercles. They bear knobs, as described by Alder and Hancock.
The anterior margin of the foot is somewhat undulated, with a bend inwards in the
middle. It is not grooved in the ordinary way, but the sides of the head are developed
into lappets, which extend downwards towards the sides of the foot and form a ridge
nearly parallel to them. There is a small fold round the head bearing two distinct
tentacles. The rhinophores bear irregular perfoliations which do not go all round the
club. The interrhinophorial crest is elongate.
The jaws are large and smooth, with no denticles. The radula consists of fifteen
rows varying from 11.1.11 to 13.1.13. The teeth are hamate and increase in size from
the rhachis outwards, the last but one being the largest, and the outermost of all smaller.
They bear three to five (rarely seven) long ridge-like denticles, which are not very small,
but difficult to see on account of the extreme transparency of the teeth. These denticles
JANOLUS HYALINUS. 123
seem to have escaped the notice of both Alder and Hancock (Tongues of the Eolididaa) and
of Bergh, who all describe the teeth as smooth. The denticulation is probably variable.
DOTO CUSPID AT A A. & H.
(Plate V, figs. 1—3.)
Alder and Hancock 2, p. 263. Alder 1, pp. 61—62.
Alder’s account of this species is as follows:
“ Body slender, white or yellowish, spotted with pink or purple; head with an
arched veil produced into recurved points at the sides; tentacles slender, tapering a little
upwards; the sheaths trumpet-shaped with scalloped margins; branchial processes ovate-
conical, with four rows of strongly pointed conical tubercles and a terminal one at the
apex; the tips are without spots ; papillae six on each side; foot narrow, a little expanded
in front. Habitat, in 75—80 f. on the Outer Haaf of the Whalsey Skerries, Shetland.
This species, of which a single specimen was obtained during the Shetland dredging
expedition in 1861, comes very near to Doto coronata, from which it differs in the papillae
having much more pointed tubercles without the terminal spot. The tentacular sheaths
also have scalloped margins and the veil is more arched than in D. coronata.”
The notes on Hancock’s drawings say “ Shetland, Mr. Jeffreys, 1861,” and repeat in
a disjointed form the substance of the above description. Of the rhinophore sheaths they
say : “ margin reflected and produced into several points, the point in front being much
larger than the others.” The preserved specimen was about 6 mm. long.
I t is unfortunate that this species is founded on a single specimen, for nearly all
Dotos are known to vary considerably in colour and shape. Still the shape of the cerata
as drawn and described seems a valid specific character: it distinguishes D. cuspidata
from D. coronata and D.fragilis, and D. pinnatifida is clearly a separate species. Nothing
is known of the buccal parts and internal anatomy, but the known species of Doto do not
show much variety in this respect.
As a name Doto cuspidata has priority over the numerous species created by Hesse
(1873) and Trinchese (1877—9). I t is perhaps identical with D. cornaliee Trinchese,
which differs from it only in having a pink ring formed of minute spots round the bases
of the cerata. Alder and Hancock (2) say that D. cuspidata is “ spotted on the back with
pink or purple, the spots forming two lines of curves between the branchiae,” which may
be a way of describing imperfect rings. I t is possible that Trinchese’s D. costse and
D. aurea are also varieties of this same species, for different as they are in general
appearance they have the same characters: conical cerata with prominent pointed
tubercles, scalloped rhinophore sheaths, and a coloration consisting of a yellow or white
ground with darker mottlings formed by minute spots.