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Show 1884.] 'LIGHTNING' A N D 'PORCUPINE' EXPEDITIONS. 121 Distribution. Arctic Norway southwards along the western of Europe to the iEgean archipelago, Madeira (Watson), and Teneriffe in the Canary Isles (McAndrew) ; 0-120 fms. Fossil. Pliocene: Norwich Crag, Italy. Post-tertiary : Norway and Sweden, Scotland and Ireland, Rhodes; 0-100 ft. This may he the Turbo albus of Adams (Trans. Linn. Soc.) and Turbo albidus of Maton and Rackett, and if so, the first of those names would take precedence of any other; but they may be considered antiquated. R. rudis, R. nana, B. radiata, and B. granulum of Philippi were erroneously given by me in my paper on the Piedmontese Testacea as varieties of the present species ; that, however, was nearly thirty years ago, and I have since seen all these species instead of the descriptions of them. Morch united, but wrongly as I believe, B. albella and B. sarsii with B. inconspicua as varieties. The sculpture is excessively variable, as regards not only the number and comparative strength of the longitudinal and spiral striae, but even their existence. Some specimens are marked with one or two varices or larger ribs. The variety variegata is peculiar, and has been made a distinct species by Schwartz v. Mohrenstern. 27. RISSOA DELICIOSA \ Jeffreys. (Plate IX. fig. 7.) S H E L L conic-oval, rather thick, semitransparent, and glossy: sculpture, short, sharp, and somewhat curved longitudinal ribs or striae, of which there are from 16 to 20 on each of the three last whorls, the first and second whorls being smooth; these ribs or striae do not extend below the periphery ; they are crossed by more numerous spiral striae or thread-like lines, the six lowermost being much stronger than the rest; this intercrossing, however, does not impart to the surface a reticulated appearance, because the longitudinal ribs are much thicker and less numerous than the spiral striae: colour milk-white: spire short, bluntly pointed: whorls 5, convex, gradually enlarging; apex bulbous : suture deep : mouth more round than oval, angular above: outer lip simple and rather thin, but strengthened outside by a thickened rib: inner lip folded over the pillar and forming with the outer rib a continuous or complete peristome: base compressed or slightly concave, and having a narrow chink behind the pillar-lip. L. 0*075. B. 0*05. Var. multicostata Longitudinal ribs much more numerous, finer and straight; spiral striae also more numerous, but slighter and less distinct except at tbe base. Some specimens have much more delicate and close-set sculpture than is shown in the figures; and in other specimens the sculpture almost disappears. The variety, if it can be properly considered distinct, is connected with the typical form by intermediate gradations. Species-makers would revel in this kind of manufacture. 'Porcupine' Exp. 1870: Atl. St. 9, 13, 16, 17, 17a, 24, off C. Sagres, 26-34, 36 ; Med. 50, Adventure Bank, 58. 1 Delightful. |
