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Show 1885.] 'LIGHTNING' A N D 'PORCUPINE' EXPEDITIONS. 45 but Fischer de Waldheim's name of Xenophora has the priority three years over that of Montfort. The apex of the shell forms a short but compact cone of several smooth whorls. Family XXIV. VELUTINID^E. 1. LAMELLARIA PERSPICUA, Linne. Helix perspicua, L. S. N. p. 1250. L. perspicua, B. C. iv. p. 235, pi. Hi. f. 6 ; v. p. 235, pi. lxxix. f. 2. 'Porcupine' Exp. 1870: Atl. St. 26; Med. Rasel Amoush, G. Tunis. Distribution. Norway, Faroe I., Great Britain and Ireland, Brest (Daniel), Atlantic coasts of France and Spain (Hidalgo), throughout the Mediterranean and Adriatic, Canaries (McAndrew), Labrador, Canada, United States ; 0-108 fms. Fossil. Pliocene: Coralline Crag, Monte Mario, Calabria, and Sicily. Bulla haliotoidea and Lamellaria tentaculata, Montagu, Marsenia producta and complanata, Leach, Sigaretus vitreus, O. G. Costa, and S. audouinii, Cantraine ex typo. 2. LAMELLARIA TENUIS l, Jeffreys. (Plate V. figs. 5-5 b.) S H E L L nearly circular in outline with a concave base, thin and fragile, semitransparent and glossy: sculpture, extremely delicate, close-set, and microscopic spiral striae ; these are sometimes wanting on parts of the surface: colour clear white : spire small, laterally placed and depressed : whorls 2|, rather convex; the last occupies five sixths of the shell; the first or apical whorl is sunken, incomplete, and twisted inwards : suture narrow, but deep : mouth nearly round and expanding: outer lip projecting above the periphery, and forming at the base a short and slightly reflected pillar: inner lip none: umbilicus small, but distinct and deep. L. 0-1, B. 0-15. 'Porcupine' Exp. 1870: Atl. St. 16. Four specimens. It differs from Sigaretus excavatus of Searles Wood in shape, the spire, and the umbilicus, as described and figured in his Monograph on the Crag Mollusca. This delicate little shell appears to be internal and completely enclosed within the mantle of the animal, because of its fragility, the incompleteness of the nucleus, and its not having any trace of an epidermis, which is conspicuous in Sigaretus striatus or haliotoideus. But the distinction between Lamellaria and Sigaretus is not so well defined as could be wished. The chief difference consists in the presence or absence of an operculum. The sculpture of the present shell resembles that of certain species of Philine. 1 Thin. |
