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 Thetis, sp. nov. — (Fig. 32)
Triforis Thetis, sp. nov.
Shell small and slender. Colour uniform cinnamon-brown except a patch of dark chocolate on the columella. Whorls fifteen. Protoconch five whorled, the later three bicarinate, page 446crossed obliquely by numerous fine bars which bead the carinæ. The adult whorls are beset with two bead-ridges, carrying each about sixteen gemmules of equal size to a whorl, vertically the gernmules run slightly oblique, between each ridge is a deep and narrow groove. In the antipenultimate whorl a thread appears in this groove and ultimately grows on the last whorl to a gem-mule row. A raised thread beneath the suture ascends for a few whorls. The last whorl is ornamented by this thread followed by a row of large gemmules, two rows of smaller ones, an incipient peripheral row and two minor, basal, subnodulose ridges. The gemmules are coloured, polished, hemispherical, truncated and shelved above, and stand nearly their diameter apart on the ridge.
The suture is deep and well denned. Between the gemmules the surface is roughened by minute spiral threads cut by oblique growth lines. Aperture vertical, nearly square. Outer lip crossing the pillar in a spur. Anal notch a simple open fold. Canal short and briefly recurved. Length 4, breadth 1 mm.
Shallow water in the Funafuti lagoon, several specimens.
Seeing that Tryon, whose standard of description was not severe, concludes his monograph of the genus with a list of eighty unrecognizable Triforis, I have no confidence that the species above described has not previously appeared in literature, though I am sure that it has never been properly characterised. It is probably near, and possibly identical with, T. limosa, Jousseaume. That writer (as repeated by Tyron) neglects the important details of apex, anal notch, etc., and the fact that the Funafuti shells are but page 447half its size, has decided me, in the absence of other information to regard it as distinct. A shell from Port Moresby closely resembles the Ellice one, differing by larger size and more swollen contour.