Range, habits, &c.—I have received specimens from all parts of the coast of Great Britain and Ireland, generally attached to crustacea and mollusca, and never hitherto from rocks uncovered by the tide. This species is also attached to floating timber, sticks, fuci, and occasionally to pebbles at the bottom of the sea. Mr. Thompson has sent me specimens from twenty-five fathoms depth in Belfast Bay: others on a Pinna from about fifty fathoms on the coast of Antrim; others from between three and six fathoms attached to Laminaria digitata: there is a specimen in Mr. Jeffreys’ collection marked forty-five fathoms. It is often associated, both on the coasts of America and Britain, with [B. porcatus], and though these species are so distinct, yet when both have their surfaces similarly affected by being attached, as is often the case, to large Pectens, it is not at first easy, by external characters, to distinguish them, except by close inspection of the terga, which in [B. porcatus] are beaked and purple. The [B. crenatus] is sometimes associated in deep water with [B. Hameri]. At Ramsgate, in Kent, I saw a rudder of a ship, in which the two or three upper feet were thickly coated with [B. balanoides], and the two or three lower feet with [B. crenatus] and [improvisus] mingled, together with a few of [B. balanoides]: occasionally vessels are thickly encrusted with this species, but I have never seen an instance of its concurrence with [B. tintinnabulum] and [amphitrite]—the commonest species on ships coming from the south. I have seen specimens from Greenland, Baffin’s Bay, the coast of Labrador, and other specimens marked simply, “Arctic regions,” and, again, others from the shores of Maine and Massachussetts. The arctic specimens, and those from the northern United States, are larger than the British. I have seen one single minute specimen on a crab, marked as having come from the Mediterranean. In the British Museum, amongst some specimens of [B. eburneus], ticketed as having been sent from Jamaica, there was a small group of specimens, differing in no one essential respect from the common varieties of [B. crenatus]: at first I concluded that this was an erroneous habitat, and that the specimens had really come from the United States, where [B. eburneus], is found as well as in the West Indies: for it appeared to me exceedingly improbable that an animal which can exist in lat. 75° N. should inhabit the hot shores of Jamaica: but subsequently I have received a specimen from Prof. Krauss, collected by himself in Algoa Bay, which is perfectly characterised, and even has the little cells in the furrow under the sheath: so that I am compelled to admit this enormous range and capability of resisting the most extreme climates. That this species should live in the tropical seas is the more surprising, as the large size of the specimens in the northern seas and in the glacial deposits, might fairly have been supposed to have indicated special adaptation for a cold climate. The great geographical range of this species accords with its range in time from the present day to the Coralline Crag period.
The specimens from the glacial deposits which I have examined, chiefly in Sir C. Lyell’s collection, are very fine and large; they are often associated, like the now living individuals, with [B. porcatus] and [Hameri]: they come from the well-known formation of Uddevalla and from Canada. There are well-characterised specimens in the mammaliferous Crag, at Bramerton and near Norwich, in Sir C. Lyell’s collection, and from Sutton and other places in the Red Crag of the eastern shores of England: these specimens are decidedly not only smaller than the glacial, but than the recent English specimens; for the largest Crag specimens which I have seen had a basal diameter of only .35 of an inch. The specimens which I have seen from the Coralline Crag, and some others sent me by Krantz from the miocene formation of Flonheim bei Abzei, in Germany, had not their opercular valves, yet I cannot doubt, considering how few species there are in the present section of the genus, that I have rightly identified them.
Diagnosis.—Under the head of [B. balanoides] I shall make a few remarks on the diagnosis between that and the present species; as [B. improvisus] is found on the British shores, sometimes mingled with [B. crenatus], I may observe that, externally, the only difference consists in the edges of the radii in [B. improvisus] being much smoother and rounded, and in the whole shell being less rugged. Internally, in [B. improvisus] the porose basis, the presence of an adductor ridge on the under side of the scutum, the graduated teeth on each side of the central notch in the labrum, and the little inequality in length of the rami of the first pair of cirri, are clearly and amply diagnostic.
28. [BALANUS] GLANDULA. Pl. [7], fig. [1 a], [1 b].
Shell white; parietes with the internal lamina generally strongly ribbed longitudinally, with the pores imperfect and small, sometimes in part absent; radii narrow, with their summits rounded. Scutum with an adductor ridge; tergum with the spur truncated and rounded.
Habitat.—California, Mus. Cuming, Aug. Gould; attached to shells and wood, together with [B. nubilus]. Southern Pacific ocean, attached to Pollicipes polymerus; Mus. Brit.
General Appearance.—Shell steeply conical, or cylindrical and elongated; dirty white; walls rugged, longitudinally folded; radii narrow, with their summits very oblique and rounded; orifice toothed. Basal diameter of largest specimen half an inch.
Scutum, resembling externally that of [B. crenatus]; rather broad, surface smooth; articular ridge very prominent, and articular furrow very wide; hence, when the summits of the opercular valves are worn down, the two scuta together form a square projection indenting the two terga, as in [B. balanoides]. Internally, there is a small adductor ridge, on the lower side of which there is a pit, as if for a muscle. The depression for the lateral depressor muscle is small, but variable. Tergum without any longitudinal furrow, and hardly a depression: spur broad, with its lower end truncated and rounded; internally, articular ridge very prominent; crests for the depressores well developed.