The Atoll of Funafuti, Ellice group : its zoology, botany, ethnology and general structure based on collections made by Charles Hedley of the Australian Museum, Sydney, N.S.W.
Triforis ægle, Jousseaume. — (Fig. 27)
Triforis ægle, Jousseaume.
Jousseaume, Bull. Soc. Mal. France, 1884, p. 256, pl. iv., fig. 12; Tryon, Man. Conch., ix., 1887, p. 185, pl. xxxix., fig. 40.
Jousseaume's account, as reflected in Tryon's Manual is too scanty to allow of a proper determination, and with much doubt I assign here a Funafuti species. A single specimen of T. œgle, from Noumea, presented by Mr. R. C. Rossiter, now before me, is too immature to show the aperture. It is a larger and lighter coloured shell than those from Funafuti, and the gemmules seem rather closer together. As, however, it fairly corresponds to the Ellice shells in apex and sculpture, I prefer, instead of adding another name to the long list of Triforis, to assume that the one figured and described below is a variety of Jousseaume's species. The still more scanty information published relative to T. collaris, Hinds, suggests that it should also be compared.* page 440
Shell rather narrow, tapering to a fine and slender point. Whorls fifteen. Colour ochraceous with white gernmules. Proto-conch six whorled, first two together semiglobose and shagreened; remainder keeled by a single, strong, central, projecting carina, which is beaded by the passage of numerous close set delicate bars crossing the whorls obliquely. All adult whorls except the last have two rows of gernmules, about sixteen in a row, alternat-ing vertically. On the last whorl there are two additional anterior rows of smaller gernmules, an incipient row on the periphery and two minor scarcely beaded ridges on the base. The gernmules are large and very prominent, polished and reflecting a nacreous lustre, rounded anteriorly, flattened with corner angles peripher-ally and shelved atop; each is linked to its neighbours in the row by a coloured ridge; in the centre of the whorl a sharp groove runs between the two rows. The surface in general is decussated by faint growth lines crossing spiral engraved lines. Aperture nearly perpendicular, ovate, inner lip with a thick callus layer, outer lip thickened and reflected, the right margin crossing the canal in a spur; anal notch cordate, the orifice taking the place of the last sutural gemmule, canal oblique, moderately produced. Length 5, breadth 1¼ mm.
Shallow water in the lagoon. The commonest Triforis at Funafuti.
Prominent characters which distinguish this species are the large, white, facetted, gernmules contrasted against the dark background, the one-keeled apex, and the peculiar anal notch.
* Hinds—Proc. Zool. Soc, 1843, p. 23; and Journ. Conch., viii., 1897, p, 409.