LEPAS HAMERI. _Ascanius._ Icones rerum naturalium, Tab. 10, 1767.
---- TULIPA. _O. F. Müller._ Prodromus. Zoolog. Dan. 1776; sed non
_L. tulipa_, in Poli, Test. ut. Siciliæ; neenon _B. tulipa_, in
Bruguière, Encyclop. Method; neenon _B. tulipa_, in Sowerby,
Genera of Shells.
---- TULIPA ALBA. _Chemnitz._ Syst. Conch. Tab. 93, fig. 832.
---- FOLIACEA. _Spengler._ Skrivter of Naturhist. Selskabet, 1 B.
1790.
BALANUS CANDIDUS. (Tab. emendata) _Brown._ Conch. Great Britain
(1827), Tab. 6, figs. 9 and 10, et 2d edit. Tab. 54, figs. 9-12.
---- TULIPA. _Lyell._[98] In Phil. Transact., 1835, p. 37, Tab. 2,
figs. 34-39.
[98] Sir C. Lyell remarks that this is apparently the _B.
Uddevallensis_ (Linn.) of Swedish lists of fossils. Prof. E. Forbes
has shown (Mem. Geolog. Survey of England, vol. 1, p. 364) how this
name arose, from a short description, prior to the introduction of
the binomial system, "Lepas quæ Balanus Uddevallensis," given by
Linnæus in his Wast-Gotha Resa, in 1747.
For the reference to Ascanius' work, which is on the binomial
system, and subsequent to the 10th edit. of Linnæus, in 1758, I am
greatly indebted to Mr. Sylvanus Hanley. Had it not been for this
gentleman, I should have used Müller's name of _B. tulipa_ as the
first name.
_Shell white: radii with their oblique summits smooth and arched;
sutural edges smooth: basis solid. Scutum feebly striated
longitudinally: tergum with the spur narrow._
_Hab._--Coast of Yorkshire; Scotland; Galway, Ireland; Isle of Man,
and Anglesey, twelve fathoms. Generally in deep water; not very
common. George's Bank, Massachussetts, United States; Mus. Aug.
Gould. Iceland, Finmark, and the Faroe Island, according to Spengler.
Attached to crustacea, mollusca, stems of fuci, and stones; often
associated with _B. porcatus_ and _crenatus_.
_Fossil._--In glacial deposits at Uddevalla in Sweden, and Beaufort
in Canada; Mus. Lyell. Banks of the Dwina, Russia; Mus. Murchison.
Greenland, "in blue clay," according to Spengler. Red Crag (Sutton)
Mus. S. Wood.
_General appearance._--Shell tubulo-conical, very smooth, white,
generally more or less covered by yellow thin membrane: orifice
large, sub-triangular: radii moderately broad, with their more
or less oblique summits slightly rounded and smooth; from this
circumstance the shell has been justly compared to the half-opened
flower of a white tulip. Specimens often exceed an inch in basal
diameter; I have seen one from Scarborough two inches in diameter
and one and three quarters in height: another specimen was 1.6 in
diameter and 3 in height. The specimens in the glacial deposits seem
even to have acquired larger dimensions, one from Uddevalla being
nearly four inches in height.
_Scuta_, elongated, flat, feebly striated longitudinally:
internally, articular ridge short, moderately prominent: adductor
ridge, confluent in the upper part with the articular ridge,
running straight down and forming a rather large cavity for the
lateral depressor. _Terga_ feebly striated longitudinally, with a
longitudinal furrow, having the sides, in old specimens, partly
closed in: the basal margin slopes much towards the spur, which is
rather long and narrow, with its end rounded: it is placed at about
its own width from the basi-scutal angle. Internally, articular
furrow narrow; crests for the depressores moderately prominent, but
in a variable degree.
_Compartments_: these are unusually thin, and separate easily: the
parietes are finely ribbed longitudinally on their insides; the
bases of these ribs being just perceptibly denticulated. _Radii_,
with their summits oblique (usually at about an angle of 45°),
slightly arched and quite smooth: the smoothness is produced by the
edge being a little inflected: sutural edge quite smooth, without
even a trace of septa or denticuli. _Alæ_ oblique, generally rather
less oblique than the summits of the radii: sutural edges smooth,
with an excessively fine linear furrow running along the edge, a
little towards the inner side, and filled with a yellow ligamentous
substance: a furrow of this kind I have seen in no other species.
_Basis_, solid, not permeated by pores; either smooth, or slightly
furrowed in lines radiating from the centre.
_Mouth_: labrum with scarcely perceptible minute bead-like teeth
thinly scattered along the edge. _Palpi_ and _outer maxillæ_ rather
sparingly clothed with hairs. _Mandibles_ with teeth rather sharp;
the fourth and fifth teeth small, but well developed; inferior angle
pointed with fine spines. _Maxillæ_ with a deep notch under the two
upper great spines. _Cirri_, the first pair is short, with rami of
nearly equal length: the segments are not protuberant in front either
in the first or second pairs. In the posterior cirri, the segments
bear four pairs of spines, with a tuft of rather long intermediate
spines: in young specimens there are only three pairs: the spines in
the dorsal tufts are short and thin.
When the shell is disarticulated, this species cannot be confounded
with any other; but judging by external characters alone, it may
sometimes be very easily confounded with _B. eburneus_, and I have
received the two species under this one name from Massachussetts:
generally _B. Hameri_ may be distinguished from _B. eburneus_ by
the smoothness of the summits of its radii, and by the so-called
epidermis being of a darker yellow.
With respect to the fossil specimens from the glacial deposits,
I have little to add; I have seen one from Uddevalla, as already
remarked, four inches in height, and a lateral compartment broader by
one fourth than the same compartment in any recent specimen. As Sir
C. Lyell remarks (Phil. Transact.), the compartments are always found
separated, which is accounted for by their weak union in a recent
state. This species, when fossil, is usually associated with its
deep-water congeners _B. porcatus_ and _crenatus_, as at the present
day.
I must here mention that I have examined a considerable number of
_separated_ compartments, without opercular valves, brought from
Barbados, in the West Indies, showing the existence there of a
closely allied or possibly identical species. The only difference
which I can point out in these compartments is, that the parietes
are rather thicker, and the radii rather narrower, with more oblique
summits: some of the compartments are two inches in length. It seems
very improbable that the true _B. Hameri_ should extend to the West
Indies, but after what has been seen in the case of _B. crenatus_,
this is possible.