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(Pl. I., figs. 11-11c.)
Shell subglobose, rimate, very thin, semi-transparent, pale horn colour, covered with a periostracum which invests the entire surface, including the apex, and which, when moistened, is thick, but shrinks and seems thinnish when dry. It is produced at the upper part of the whorls, a little below the suture, into a series of short spines, forming a sort of coronation. Whorls three, very convex and rapidly increasing; the two apical (the periostracum being removed) are whitish, glossy, glassy, and finely spirally striated; the last is very large, globose, exhibiting oblique lines of growth of periostracum, which are produced over the deep canaliculated suture. Aperture broadly pyriform; periostome thin, simple, the columellar margin, however, being of a brown colour and somewhat reflexed.
Greater diameter, 7 millim.; height, 8; aperture 5.25 millim. long , 4.5 wide.
The operculum (fib. 11b), is horny, reddish, somewhat triangular, with the outer margin curved, the converging sides straight, the nucleus terminal and marked with rather coarse, curved lines of growth.
Off Coulman Island, in 100 fathoms.
Only a single specimen was obtained. It has the appearance of being the young state of a shell that might grow to a considerable size, judging from the large apical whorls. When first received, before its removal from the spirit, the periostracum was thick and spongy, and enveloped the entire shell, and had the appearance of being keeled at the upper part of the body-whorl.
The foot of the animal has a double margin in front, the tentacles are rather short, subulate, with the eyes sessile at their outer bases, and the head is prolonged into a long, slender rostrum. Radula (fig. 11c) 2, 1, 1, 1, 2, tapering towards the anterior end. Central tooth with a median cusp, and two smaller ones on each side; laterals with three or four cusps, inner marginal tri- or quadri-cuspidate; outer marginal simple, hooked.
The Rev. H. M. Gwatkin, who very kindly extracted and mounted this radula for me, considers that it approaches that of Crepidula and Calyptræa. The character of the shell and the presence of an operculum at once separate it from those groups. It apparently represents a new generic type, for which I would suggest the name Neoconcha.”
(Smith, 1907: 6)