BALANUS CALCEOLUS KERATOPHYTO INVOLUTUS (?) _Ellis._ Phil. Trans.,
vol. 50 (1758), Tab. 34, fig. 19.
LEPAS CALCEOLUS (?) _Pallas._ Elench. Zooph., p. 198, (sine
descript.) (1766).
CONOPEA OVATA (?) _J. E. Gray._ Annals of Philosophy, vol. x, 1825.
_Parietes and basis porose. Scutum with the pit for the lateral
depressor muscle small and deep._
_Hab._--Attached to Gorgoniæ, West Coast of Africa. Tubicoreen, near
Madras, (Dr. Johnston), associated with _B. navicula_. Mediterranean
(?). Mus. Brit., Cuming, Stutchbury.
_Fossil._ Coralline Crag; Mus. S. Wood.
I must premise, with respect to the nomenclature of this and the three
following quite distinct species, that in the published descriptions
no allusion is made to any one of the characters by which alone
they can be distinguished: hence I have been guided by geographical
probabilities in assigning the specific name of _calceolus_ to the
present species, as Ellis's specimens came from the Mediterranean; and
that of _galeatus_ to the North American and West Indian specimens, as
Linnæus' original specimens (according to a statement by Spengler) came
from the West Indies. I have assigned new names to the two remaining
East Indian species. I may here add that Spengler ('Skrifter af
Naturhist.' 1 B, tab. 6, fig. 3, 1790) has described, under the name of
_B. cassis_, an allied form attached to the _Gorgonia placomus_ from
the seas of Norway; but I do not believe that it is the same with our
present species.
_General Appearance._--The degree of elongation of the shell in
its rostro-carinal axis varies considerably (3 _a_, 3 _b_): the
elongation is due to the production of the rostrum and of the
corresponding end of the basal cup. These two portions of the
shell always form together an angle, and sometimes an acute angle,
whereas in all the many specimens which I have seen, the carina and
the carinal end (or heel) of the basis together form a straight
line; yet I should not be surprised if this end of the shell was
sometimes produced. The surface of the shell is smooth, or sometimes
marked with very minute projecting points: it is almost always
covered by the horny bark of the Gorgonia. The colour is either dull
purplish-red or dull purple, with obscure longitudinal stripes,
and often more or less transversely banded with white. The rostrum
is either white or very feebly tinted, being always paler than the
rest of the shell: the radii are usually paler than the parietes,
and are sometimes white: the carinal end of the basal cup is tinted
of the same colour with, but rather paler than, the compartments.
The orifice is rather small compared to the shell, and nearly
heart-shaped. The carino-lateral compartments are about one-third of
the width of the lateral compartments. The shell is very strong, and
the sutures resist the action of boiling caustic potash. The largest
specimen which I have seen was .7 of an inch in extreme length, and
under .25 in extreme breadth.
_Structure of the shell and basis._--The parietes are permeated by
quite distinct pores,--a character sufficient by itself to separate
this from the following species; the longitudinal septa forming the
tubes are slightly denticulated at their bases. The radii have their
summits quite square, extending from apex to apex of the adjoining
compartments. The alæ have oblique summits. The sutural edges of
the radii have approximate septa, which are obscurely denticulated:
the interspaces are filled up solidly, so that the radii are not
porose. The basis is distinctly porose, by which this species can be
distinguished from _B. navicula_ and _cymbiformis_. The basis has a
deep furrow on the under side, from clasping the thin horny axis of
the Gorgonia: the basal point of the rostrum is also notched from the
same cause, and, as a consequence, its upper surface becomes slightly
furrowed along its whole length.
The _Scuta_ have an articular ridge but moderately prominent, and
only slightly reflexed; the basi-tergal corner is rounded off; there
is no adductor ridge; there is a small, rather deep, distinct pit
for the lateral depressor muscle. _Terga_; externally the surface is
considerably depressed in the line of the spur. The spur is between
half and one-third of the width of the valve: its lower end is square
and truncated, or in some degree rounded; it is sometimes (3 _e_)
dentated with a few, minute, sharp teeth. The articular ridge is but
slightly developed; the crests for the depressor muscle are very
feeble.
_Animal's body_ unknown.