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“Natica prasina, n. sp.
St. 149 D. Jan. 19, 1874. Lat. 49° 32' S., long. 70° E. Balfour Bay, Royal Sound, Kerguelen. 60 fms. Mud.
St. 149 E. Jan. 20, 1874. Lat. 49° 28' S., long. 70° 13' E. Royal Sound, Kerguelen. 28 fms, Mud.
Shell.—Conically globose, rather high in the spire, with umbilicus closed, thin, with a pale green roughish epidermis. Sculpture. Longitudinals—there are on the lines of growth slight puckerings of the fibrous epidermis. Spirals—there are some slight, open, irregular, and unequal furrowings of the surface, with microscopicscratchings. Colour: a pale buff colour below the dull greenish epidermis, which is fibrous, thin, easily rubbed through, but persistent. Spire more or less high, the whorls rising very considerably above each other in high rounded steps. Apex extremely large for the size of the shell but not prominent, being rounded, with the extreme tip sunk in and generally eroded. Whorls 5, of which about 1¼ are embryonic; they are globose, and increase regularly and slowly. Suture deep, very slightly channelled, straight, but towards the end a little oblique. Mouth large, open, circularly oval, little oblique, right-angled above, fully rounded below, with a scarcely perceptible angulation towards the point of the pillar, slightly flattened on the inner lip; its height is nearly seven ninths of the whole height. Outer lip—leaving the body-whorl at a right angle, it sweeps round very fully and regularly to the pillar; it is thin. Inner lip a little hollowed, with, on the body, a very slight projection; there is scarcely any pad at the upper corner of the mouth, and the callus is very thin on the body; above and at the umbilicus it is thinly and somewhat broadly reverted, so as quite to conceal the opening or to leave at most a mere chink; at the pillar it narrows, and there is at this point a slight transverse angulation; the pillar is the only part of the lip which is at all thickened, and that but slightly; the edge is rounded and slightly levelled back. Operculum is membranaceous, thin, with a distinct and slightly impressed suture, and scored with sharp radiating lines. H. 0.64. B. 0.53. Penultimate whorl, height 0.15. Mouth, height 0.49, breadth 0.47.
N. globosa, King, from the Straits of Magellan, is somewhat like this, but has a much more depressed spire and longer mouth. Prof. v. Martens was good enough to compare this species for me with his N. grisea, and from that he says "it differs (1) by being considerably larger, (2) thinner, (3) penultimate whorl less prominent, (4) the last whorl, when seen from the dorsal side, is higher or longer relatively to the breadth, (5) the umbilicus is narrower; I think, therefore, that it is a distinct species, and I see also no other in the Berlin collection which might be identical."
(Watson, 1881: 263-264)