LEPAS SPONGITES. _Poli._ Testacea utriusque Siciliæ, 1795, Tab. 6,
fig. 3-6.
BALANUS SPONGEOSUS. _Montagu._ Test. Brit. Suppl., 1808.
---- SPONGITES. _De Blainville._ Dict. Sc. Nat., Pl. 116, fig. 3.
LEPAS SPONGIOSA. _Wood's_ General Conchology, p. 47.
ACASTA MONTAGUI. _Leach_, in Lamarck, Animaux sans Vertèbres, 1818,
et in Encyclop. Brit., Supplement, 1824, vol. 3, Pl. 57.[103]
---- ---- _J. E. Gray._ Annals of Philosophy, New Series, vol. 10,
Aug. 1825.
---- SPONGITES. _Philippi._ Enum. Mollus. Siciliæ, vol. 2, p. 211,
1844.
BALANUS MONTAGUI. _Brown's_ Illustrations of Conchology (2d edit.
1844), Pl. 53, fig. 24-26.
[103] As the plate to the Supplement to the 'Encyclop. Brit.' is
marked as engraved in 1817, I presume Dr. Leach gave a proof to
Lamarck, thus enabling him to publish this species four years
before the Supplement itself appeared.
_Carino-lateral parietes about one sixth of width of lateral parietes:
inner surface of the parietes generally ribbed feebly: scutum with the
articular ridge abruptly cut off at its lower end: tergum with the spur
rounded-truncated, about one third of width of valve._
_Hab._--South coast of England; South Wales, (Tenby); Portugal;
Naples; Sicily; Cape of Good Hope.
This species and the three following, have caused me much doubt and
trouble. At first I took the view here adopted, namely, that they
were distinct: more careful examination made me run them altogether
under one name. Finally, after still further deliberation, and the
examination of a few additional specimens, I concluded there was the
least chance of error in classing them separately. I may here mention,
that in some sponge from the Cape of Good Hope, this species was
mingled with _Balanus spongicola_.
_General Appearance._--The shape is usually that of a cup, the
orifice being, in most cases, rather large, and deeply notched, owing
to the great obliquity of the radii and alæ. The surface is generally
smooth, but furnished with sharp calcareous projections. The colour
is pinkish, and chiefly in the upper part of the shell; the lower
part is often yellowish from the preserved epidermis. The parietes
in the carino-lateral compartments are always narrow, being only one
sixth or one seventh of the width of the parietes in the lateral
compartments. The radii are not very wide, never equalling in width
the parietes. The basis is moderately deep, and sometimes very deep,
being even occasionally curled like a horn on one side. The specimens
from Lisbon and Naples are a little larger than any British specimen
which I have seen; the former being .3 of an inch in basal diameter.
_Scuta_: these are striated longitudinally in close lines, generally
plainly, but to a variable degree. The whole valve is flat, thin,
and rather elongated, with barely a trace of an adductor ridge:
the articular ridge is short and rather prominent: it terminates
downwards abruptly, and this does not appear to be the case in the
two following species. _Terga_: these are small compared with the
scuta, they are slightly beaked: the spur is truncated but rounded,
more especially on the carinal side; it is rather more than one third
of the width of the whole valve. The articular ridge and crests for
the depressor muscles are feebly developed.
_Structure of the Parietes and Radii._--The state of the inner
surface of the parietes varies much; generally they are slightly
ribbed close to the basis, the ribs sometimes extending up to the
sheath; rarely the surface is quite smooth. The edges of the radii
are slightly crenated. The upper internal surfaces of the radii,
where overlying the alæ, are usually marked by feeble undulating
lines, nearly parallel to the basis. The alæ have very oblique
summits.
_Basis_: this is generally of a regular cup-like form, and about two
thirds as deep as the shell is high; sometimes it is pointed at the
bottom and distorted. The edge is feebly crenated, and rarely quite
smooth. It is often penetrated by small rounded irregular holes; and
I have seen specimens from the Cape of Good Hope with parts like a
sieve.
_Cirri_: in the first pair, the anterior ramus is nearly thrice as
long as the posterior ramus. The second cirrus is short, with one
ramus longer by three or four segments than the other ramus; the
terminal segments are truncated. The third cirrus is about one third
longer than the second cirrus. In the anterior ramus of the fourth
pair, the regular pairs of spines are rather crowded together in the
upper part of each segment, and the intermediate little spines and
dorsal tufts are rather long in comparison with those of the fifth
and sixth pairs of cirri: moreover, amongst the regular pairs, a few
very minute and thick spines, pointing upwards, could be perceived.
So that we here have the very unusual case of the fourth cirrus not
exactly resembling the fifth and sixth pairs; and we shall see, in
the following species, that this same anterior ramus of the fourth
cirrus presents in addition another very extraordinary character. In
the sixth cirrus there are on each segment four pairs of spines.