1893.
1894.
1897.
1904.
1905.
1906.
1907.
1908.
1909.
1910.
1911.
1914.
1915.
1916.
1917,
Sabella reniformis, Lo Bianco. Atti Acad. Sc. Nap., 2° ser., v, p. 67.
Potamilla „ Bidenkap. Christ. Vid.-selsk. Forhandl.,- p. 136.
j| „ De St. Joseph. Ann. Sc. nat., 7® s£i\,xvii, p. 292, pi. xi, figs. 296—298.
„ „ Michaelsen. Polych. deutsch. Meere., p. 182.
„ „ Journ. M. B. A, vol. vii, p. 231.
Pseudopotamilla reniformis, Bush. Tubic. Annel. Pacific, p. 203, pis. xxxiii, xxxiv and xxxvii.
Potamilla reniformis, De St. Joseph. Ann. Sc. nat., 9° ser., t. iii, p. 241.
„ „ Soulier. Trav. Acad. Sc. Montpel., 2e s6r., t. iii, p. 121.
Pseudopotamilla reniformis, Moore. Proc. Acad. Nat. Sc. Philad., p. 359.
Potamilla neglecta, Ehlers. Deutsch. Tiefsee Exped., p. 154, Taf. xxii, figs. 5—17.
„ reniformis, Fauvel. Bull. Inst. Oceanogr., cxlii, p. 42.
? „ neglecta, Moore. Proc. U.S. Nat. Mus., vol. xxxvii, p. 145.
,, reniformis, Fauvel. Ann. Sc. nat., 9° s6r., t. x, p. 210.
„ „ Elwes. Journ. M. B. A., vol. ix, p. 65.
,, Fauvel. Bull. Inst. Oceanogr., cxciv, p. 37.
J} „ Riddell. Proc. Liverp. Biol. Assoc., vol. xxv, p. 65.
„ ,, Southern. ’ Proc. Roy. Irish Acad., vol. xxxi, No. 47, p. 138.
i} „ Fauvel. Campag. Scient. Monaco, xlvi, p. 314.
,, ,, Allen. Journ. M. B. A., vol. x, p. 642.
„ ,, Southern. Irish Sc.. Invest., No. 3, p. 49.
„ ,, McIntosh. Ann. Nat. Hist., ser. 8, vol. xvi, p. 7.
„ ,, Rioja. An61. Poliq. Cant&b., p. 63.
Habitat.—Procured at extreme low water in fissures of rocks, at Guernsey and Herm;
also dredged in grooves in Pecten, and in tunnels in oysters; in swarms in the G-ouliot
Caves, Sark, where their tubes project from almost every chink, and occasionally they
are in groups, besides perforating the Balani on the floor and ledges. It spreads its tubes
through sponges and ascidians, bores the masses of Gellepora and various shells such as
limpets; tubes from Connemara (A. G. Moore) were crowded with the tubes of a sessileeyed
crustacean. Plymouth (Allen); Torquay (Ehlers); West Coast of Ireland,
Blacksod Bay, etc. (Southern).
DistHbution.—The distribution of this form is wide, viz. from the Arctic Seas to the
Mediterranean; Norway (Sars); Behring’s Sea (Marenzeller); Finmark (Norman); Iceland
(Leuckart); Greenland and Finmark (Malmgren); shores of Cantabria (Rioja); St.
Lawrence, Canada (W. C. M.); Atlantic Coast, North America (Leidy and Verrill).
North Pacific Coast of North America (Moore); shores of France (De Quatrefages,
De St. Joseph, Fauvel); Mediterranean and Adriatic (Grube, Panceri, Marion and
Bobretzky) ; Madeira and Teneriffe (Langerhans, Fauvel); Naples at considerable depth
(Lo Bianco).
The cephalic plate, when the branchiae are shed, presents dorsally a bilobed collar or
lamella, the deep dorsal furrow terminating in the centre. The outer edge of each flap
is continued as a broad rim nearly to the mid-ventral line, where a notch separates the
two sides, which curve forward. The truncated surface has a projecting transverse
fold at the upper end of the ventral incurvation, and two folds meet above it so as
to make a triradiate aperture.
The branchiae are about ten or eleven (twelve to fifteen, De St. Joseph, Leuckart)
in number on each side and comparatively short, whilst the pinnae are long. Each
filament has the transversely barred or camerated chordoid axis, and tapers to a short
filiform tip, which, however, is usually enveloped by the long pinnge or is in screw-like
coils. The pinnae have the translucent axis as in 8. penicillus with long joints, and are
richly ciliated. In life the branchiae are of a pale green marked with white touches, so
that they form a whitish ring around the collar, within which they are attached. The
pinnae are variegated with pale greenish and white and show vermiform movements when
cast off. In some the branchiae are of a pale buff hue with a little yellow at the tips of
the filaments. In contraction they are generally of a dull stone colour. Leuckart’s
examples had whitish branchiae with brownish touches, and De St. Joseph describes his
examples as vinous-brown. Sars states that his specimens had yellowish-white branchiae
with four or five orange bands. Just above the whitish ring at the base most of the
filaments have externally two boldly marked and elevated brown or reddish-brown
ocular specks separated by an interval from each other. De St. Joseph states that in
his specimens each contained about thirty ovoid “ crystalline ” in a mass of brownish
pigment. Moreover, the eyes of those from the Mediterranean are more numerous
than those from the north, whilst Marion considered that those from deep water had
fewer eyes .than the littoral forms. They are absent in a few of the filaments. The
longest filaments are dorsal, those at the ventral edge being considerably shorter and
slightly reflexed. The ocular pigment in some fades in spirit. The tentacle is com.
paratively short, but its membranous web on each side appears to agree with that in
Sabella penicillus.
The branchiae of this species are more translucent and feathery than those of
P. Torelli, the pinnae more delicate and longer, and the coloration of the two forms
diverges. The terminal processes of the branchiae are short, whereas those of P. Torelli
are long and opaque whitish. In an example of P. reniformis the bases of the branchige
were reddish brown with a pale band, whilst the rest of the filaments were pale. In
P . Torelli the branchige are boldly blotched with brownish red and white and the long
terminal filament is opaque white. The ocelli in P. reniformis are also diagnostic, and in
some they are confined to the base of the filament. The white specks on the body of
P. Torelli also differentiate.
The body is comparatively small, about three-quarters of an inch in length, and has
.from sixty to a hundred segments. It is rounded dorsally, slightly flattened ventrally, and
marked by a groove, which at the tenth segment bends from the side inward to the middle
line and divides all the scutes which follow into two. The ten scutes in front of these are
split transversely. The ventral scutes are conspicuous by their whitish or pinkish colour,
and are even visible through certain parts of the tube. Anteriorly the brownish dorsum
is marked with dark brown pigment at the bases of eleven setigerous processes, the
succeeding region of the dorsum being reddish brown. The surface is paler in the median
line dorsally and ventrally. The body is slightly tapered posteriorly, and ends in a
papillose anus, three papillae being distinct, and the colour of the tip is orange rather
than brown.
An interesting variety was procured by Arnold Watson at Llanfairfechan, Wales, in
which the anterior region consisted of no less than twenty-six segments, the first eight