BALANUS CAPENSIS ORE OBLIQUO. _Ellis._ Phil. Transact., vol. 50
(1758), Tab. 34, fig. 14.
_Shell shaded, and often longitudinally striped with bright pink.
Scutum as in B. psittacus. Tergum with the apex produced and
needle-like, white: spur placed at its own width from the basi-scutal
angle._
_Hab._--Cape of Good Hope. Attached to stems of Fuci, Algoa Bay. Mus.
Brit. and Bowerbank. Attached to a Patella, Mus. Darwin, Mus. Cuming,
and Stutchbury. Attached to floating kelp, Lagulhas Bank, Mus. James
Ross, associated with _B. tintinnabulum_ and _spongicola_.
This species comes extremely close to the South American _B.
psittacus_, and I should hardly have attached a specific name to
it, had I not examined many specimens, young and old, of the true
_B. psittacus_, from Peru, Chile, and Eastern Patagonia, and found
them all identical in the few, apparently trifling points, in
which that species differs from _B. capensis_. The animal's body
and the shell agree in every respect, excepting that the shell is
decidedly pinker, being often most distinctly and prettily striped
longitudinally with pale and bright pink. In some of the specimens
the basis is cup-formed: in some, the broad radii are pale pink,
in others they are quite white, and in this latter case a singular
aspect is given to the pinkish varieties. In very large specimens
(and I have seen one fully two inches in basal diameter) the pink
colour is extremely feeble, and the whole shell has a very rugged,
disintegrated, coarse, and sometimes dirty appearance: in most
of these large specimens the walls are more massive than in _B.
psittacus_, and the orifice of the shell rather smaller; in some,
however, the walls certainly are of unusual thinness.
The _Scuta_ differ from those of _B. psittacus_ only in the
basi-tergal corner not being so much rounded off, and consequently
in the articular ridge, which is rather more reflexed, descending in
proportion lower down the valve: the cavity at the basi-tergal corner
is in proportion broader. The valves in the two species differ, also,
but only in young specimens, in the occludent half being tinted,
both externally and internally, purple, whereas in _B. psittacus_
the whole valve, at all ages, is white. In the _terga_ the spur is
removed fully its own width from the basi-scutal angle, whereas it
is not half this distance in _B. psittacus_. The scutal margin is
here much more inflected. In _B. psittacus_ there is a remarkable
patch of purple on the inside of the valve, between the articular
ridge and a second special ridge; of this purple patch there is here
no trace, consequently the beak or apex is white. The beak, also, is
less prominent. The special ridge, just alluded to, here runs much
nearer to the articular ridge, and is less prominent: indeed, in old
specimens, it is often almost obliterated. Finally, the whole valve,
in proportion to the Scutum, is rather broader.
I have seen a young specimen, about a quarter of an inch in basal
diameter, with the orifice of the shell toothed owing to the
obliquity of the summits of the radii; and this gave the shell a very
peculiar aspect. The largest well-coloured specimen which I have seen
is 1.2 of an inch in basal diameter; but in Mr. Cuming's collection
there are two rugged, disintegrated specimens, two inches in basal
diameter, and two and a half in height. Some specimens, 1.3 in basal
diameter, in Mr. Stutchbury's collection, are remarkable from the
radii having been obliterated--the shell being merely divided by six
sutures, as we have seen is likewise sometimes the case with large
specimens of _B. psittacus_.
This species is evidently a South African representative of the South
American _B. psittacus_.