I have seen some cylindrical and conical specimens of [B. tintinnabulum], from the coast of Mexico and California, only noticeable, as far as the shell was concerned, from being rugged, and of a dull blueish-purple; but which had opercular valves exactly like those of var. coccopoma, and therefore, as far as the scutum is concerned, approaching closely in structure to var. concinnus,—all three from the west coast of America. Hence I was at one time led to believe that there existed a species on this line of coast, which represented [B. tintinnabulum], and which varied in external shape and colour in an analogous manner to that species. But as the opercular valves in var. coccopoma are sometimes identical with those of var. communis, and as this is always the case with the tergum of var. concinnus, and as the shell itself presents no differences, it is scarcely possible to admit the existence on the west coast of America of this supposed representative of [B. tintinnabulum].
With respect to var. intermedius I have little to say in addition to the character given above: I have seen only two groups of specimens in Mr. Cuming’s collection: the chief interest in this variety is that it shows that the next form must be ranked as a variety, and not as a distinct species.
Of var. occator (Pl. [1], fig. k) I have seen several specimens, mostly taken off the bottoms of vessels, and one specimen, marked in Mr. Cuming’s collection “South Seas.” After having carefully examined these specimens, I came to the conclusion, that the slightly oblique radii—the general colouring, and more especially that of the sheath—the scuta (Pl. [2], fig. [1 b]), with their sharp hood-like points, in radiating lines—and the terga, with the spur so near to the basi-scutal angle, were amply sufficient to distinguish it as a good species. Subsequently, however, I found that the scuta in var. crispatus presented, both externally and internally, exactly the same peculiar appearance. In var. intermedius, I found the summits of the radii equally oblique, and the general colouring nearly the same, and more especially a close approach to the singular circumstance of the sheath differing in colour towards the opposite ends of the shell. So that the position of the spur of the tergum was the chief remaining character; and this evidently varied considerably in the four or five specimens examined by me, being either its own width, or much less than its own width, from the basi-scutal angle: the outline, also, of the small portion of basal margin, between the spur and the basi-scutal angle, likewise varied much, being either angularly indented, or gradually curved down towards the spur: so also the tip of the spur varied in shape. The longitudinal furrow is unusually apt, in this variety, to remain open. We know that the position of the spur varies considerably in var. communis. Hence, although the spur, on an average, lies closer to the basi-scutal angle in this than in any other variety, even than in var. d’Orbignii, it would, I conceive, be preposterous to found a species on this one character. In the animal’s body, every part agrees perfectly with that of var. communis.
Lastly, we come to var. d’Orbignii (Pl. [1], fig. l): until quite recently I did not even suspect that this form was only a variety of [B. tintinnabulum]: I have examined a great number of specimens in Mr. Stutchbury’s collection, which had come attached on a vessel from Java, and likewise a few other specimens in other collections. They all closely resemble each other in shape, and even in size, and differ only in tint of colour, and in the surface being either very smooth, or longitudinally ribbed, sometimes with rugged, sharp points. From this circumstance—from the peculiarity of the tint, with the tips of the parietes and one side of the radii perfectly white—and from the obliquity of the summits of the radii, I was led to think this form specifically distinct. But the colour does not differ from that of some other varieties of [B. tintinnabulum]; the circumstance of the colour being uniform or not striped, is common to the sub-varieties of several varieties, and the white tips to the parietes, and the white borders to the radii, result simply from the shell, whilst young, having been wholly white, and this is not rarely the case with var. communis. Dismissing, therefore, colour, it will be found that hardly any other characters remain by which this form can be separated from var. occator; in both the summits of the radii are oblique, in both the sheath is coloured in nearly the same manner, in both the opercular valves, especially the terga (Pl. [2], figs. [1 m], [1 n]), resemble each other; the scuta, however, are smooth in var. d’Orbignii and rough in var. occator. This latter form, certainly, cannot be specifically separated from var. intermedius, and this assuredly is only a variety of [B. tintinnabulum]. Hence I am led to conclude that Balanus d’Orbignii of Chenu, peculiar as its whole aspect is, must be ranked only as a variety of [B. tintinnabulum]; its oblique radii resulting from the same cause, whatever that may be, which has given this structure to var. intermedius and occator; and its peculiar colouring to having been exposed (owing probably to having been transported on vessels) to different conditions, whilst young and old.
2. [BALANUS] TULIPIFORMIS. Pl. [2], fig. [2 a]-[2 d].
BALANUS TULIPIFORMIS EX CORALLIO RUBRO. Ellis.[88] Philosoph. Transactions, vol. 50 (1758), tab. 30, fig. 10.
LEPAS TULIPA. Poli. Test. utriusque Siciliæ, tab. 5, fig. 1. et 6 (1791).
BALANUS TINTINNABULUM (var.) Chenu. Illust. Conch., tab. 3, f. 5.
[88] According to the letter of the Rules of the British Association, Ellis’s name ought to be retained, as it was published in 1758, the same year during which the 10th edition of the ‘Systema Naturæ’ appeared, in which edition the binomial method was first used. But as Ellis himself did not then know of, or follow this method, it might be disputed whether, according to the spirit of the law, his name ought to stand. The only other name given to this species is that of tulipa, affixed by Poli in 1791, but this name had been previously used by Müller in 1776, and by Chemnitz in 1785, for another species, the [B. Hameri] of this work; and likewise, also previously to Poli, by Bruguière in 1789, for still another species, viz., [B. tintinnabulum] of this work: under these complicated causes of confusion, I think it is highly advisable to adopt Ellis’s name. I may add that the B. tulipa of Mr. G. B. Sowerby is the [B. tintinnabulum] of this work. It is possible that the B. conoides of Brown, ‘Illustrations Conch.’ (1st edit. pl. 6, fig. 7), may be our present species; but without details of structure it is hardly possible to identify, in many cases, the species of [Balanus].