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“NATICA FARTILIS, n. sp.
St. 145. Dec. 27, 1873. Lat. 46° 43' S., long. 38° 4' 30" E. Between Marion Island and Prince Edward Island. 50-150 fms. Grey sand.
St. 149 D. Jan. 19, 1874. Lat. 49° 32' S., long. 70° E. Balfour Bay, Royal Sound, Kerguelen. 60 fms. Mud.
St. 150. Feb. 2, 1874. Lat. 52° 4' S., long. 71° 22' E. Between Kerguelen and Heard Island, 150 fms. Rock. Bottom temperature 35.2º.
Shell.—Globose, with a rather high spire and a somewhat elongated and pointed base, thin, with a delicate light-green epidermis; umbilicus closed. Sculpture. Longitudinals—the lines of growth are fine, hair-like, close-set striæ. Spirals—the surface is somewhat distinctly, though finely, scored with shallow furrows and faint lines, which are microscopically crimped; below the suture the whorls are compressed by a broad very shallow furrow, the lower side of which is very doubtfully angulated. Colour porcellanous white under the delicate, slightly glossy epidermis, which is pale green, streaked on the lines of growth with darker green; the umbilical pad, pillar, and inside are dead white. Epidermis is a thin, rather persistent smooth membrane. Spire is rather high and conical. Apex rather large, raised so that the extreme tip projects, but rounded though not flattened. Whorls 6 (of which the first 1½ are embryonic); they are scarcely rounded between one suture and the next, with a slight and narrow margin below the suture, then very slightly compressed; the last is very large and tumid in proportion to the rest, which project very little above it; they are of slow and very regular increase to the last, which quite swallows up all the others. Suture nearly horizontal, small, not at all impressed, but very distinct, being slightly channelled, and being defined by the small margin and compression of the whorl below it. Mouth large but not very open, semicircular, oblique, almost right-angled above, rounded below; the swell of the body-whorl is just perceptible within; its height is more than seven ninths of the whole height. Outer lip very regular all the way round, its edge is thin. Inner lip a little flexuous; the upper corner of the mouth is filled up with a thinnish but broad pad, whose edge crosses the body in a
concave line; below the umbilicus, which it completely covers, it is contracted in on the pillar, which is thickish, rounded, and towards the point levelled back. Operculum tesaceous, scored with slightish radiating lines; the spire is membranaceous, being left uncovered by the limy coat; but the one specimen which preserves the operculum is a young shell. H. 0.9. B. 0.75. Penultimate whorl, height 0.19. Mouth, height 0.73, breadth 0.52.
This species so closely approaches N. affinis, Gmel. (= N. clausa, Brod. and Sow.), that I have hesitated very much to separate them, and have been glad to be strengthened in so doing by the opinion of Prof. v. Martens and of Mr. E. A. Smith. N. fartilis is more globose, higher in the spire, longer and more pointed the base, and less obliquely transverse in its outline; its apex is larger and slightly more prominent. N. globosa, King, from Magellan, like this in form, is umbilicated and has a thin operculum.”
(Watson, 1881: 264-265)