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.
Nassa semitexta, sp. nov. — (Fig. 37)
Nassa semitexta, sp. nov.
Shell broadly ovate, small, strong, opaque, white. Whorls five, of which two are apical and smooth. Remainder sculptured by small, regularly spaced, longitudinal ribs; on the last whorl these number twenty-three and vanish below the periphery. Similar spiral ribs, crossing the longitudinals, lattice the upper whorls and the upper third of the last whorl; on the penultimate there are six of these, and on the last whorl about twenty-five, which are strong and widely spaced on the periphery, weak and crowded anteriorly. A deep and narrow groove follows the suture. Aperture oblique, oval, fortified without by a thick and prominent varix, which is crossed by the spiral sculpture; columella arched, spreading a heavy sheet of callus, anteriorly incurved and terminating in a rounded knob; canal open, short, in section C-shaped. Length 6, breadth 4½ mm.
A rather worn specimen was found on the lagoon beach by myself, and another was taken by Mr. G. Sweet.
This species is referred to Nassa for the unsatisfactory reason that I do not know where else to locate it, and yet the material before me is hardly sufficient foundation for the erection of a new genus. A tubercle near the posterior angle of the aperture is characteristic of Nassa, but absent here; while the channelled suture and heavy varix developed here may not be matched in Nassa. Indeed, though the contour and anterior notch repel the idea, some aspects of this shell suggest Rissoina. Till further data, and the soft parts arrive, the true systematic position of this shell must, I think, remain in suspense.