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Show 1879.] MR. E. A. SMITH ON MOLLUSCA FROM JAPAN. 187 from the Persian Gulf (fig. 6). The Japanese examples (fig. 6]a) differ in a slight measure : they are a trifle narrower, have a very slightly more elongated canal; and the apex is brown instead of pale violet as in the typical form. In sculpture and colouring they are identical. 12. PLEUROTOMA NIPONICA. (Plate XIX. fig. 7.) Shell shortly fusiform, light brown : whorls 6£ ; nucleus consisting of 11, rather large, globose, glassy shining ; the four whorls following strongly keeled around the middle, concave above, with two or three fine spiral lirae, and also concave below the carina, margined at the upper and lower boundaries by a fine thread-like lira, arcu-ately or flexuously elevately striated above the carina, and obliquely, but in an opposite direction, beneath it; the last whorl encircled beneath the principal keel by about ten lirae, whereof the uppermost is the stoutest, the rest gradually becoming finer towards the base; the interstices between them crossed by elevated striae or lines of increment. Aperture small, brownish, occupying about three sevenths of the entire length of the shell; slit situated in the concavity above the principal carination; columella a little convex or prominent in the middle, and oblique below it; canal short, scarcely recurved. Length 7 millims., width 2\. Hab. Station 21. This pretty shell is recognizable by the strong central keel to the whorls, which are excavated above and below, and the raised stria? on the upper portion are obliquely flexuous towards the right, whilst those below the carina are obliquely straight and inclined to the left. 13. PLEUROTOMA DIFFICILIS. (Plate XIX. fig. 8.) Shell shortly fusiform, brownish horn-colour. Whorls nearly flat, strongly keeled a little below the middle, and above at the suture, with one or two thread-like spiral lirae in the spaces between these two carina? and between the subcentral one and the suture below it; lines of growth moderately distinct, raised, flexuous, and more or less oblique ; nucleus (or the three apical whorls) smooth, glass}*, shining, convex; the fourth also convex and coarsely obliquely costate ; last whorl encircled by about ten coarsish lira?, whereof the three uppermost are equal in size to the submedian carina of the upper whorls, which falls just above them on this volution ; the interstices between them coarsely striated by the lines of growth. Aperture small, occupying three sevenths of the entire length ; columella brown, coated with a smooth enamel, oblique below the middle ; slit above the submedian liration ; canal short, very little recurved. Operculum ovate, pointed at the base ; nucleus apical. Length 7 millims., width 2\. Hab. Stations 21 and 27. Of this species there are two specimens in the collection. In both there are two fine thread-like lira? in the interstice between the upper and submedian keels on the last two whorls ; but the upper one gradually becomes obsolete on ascending the spire. The upper of the |