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Show 1883.] 'LIGHTNING' A N D 'PORCUPINE' EXPEDITIONS. 93 joins the periphery; edges thin: umbilicus contracted and small. L. 0075, B. 0*075. 'Porcupine' Exp. 1870 : Atl. St. 16, 17, 17a, 27, 28. Specimens very numerous. Bistribution. Josephine Bank, Bay of Biscay (' Travailleur' Exp. 1881), Palermo (Monterosato); 103-913 fms. Differs from C. simile in shape, as well as in the raised spire and narrow umbilicus. 12. CYCLOSTREMA BITHYNOIDES1, Jeffreys. (Plate XIX. fig. 6.) S H E L L oval, thin, having a somewhat frosty appearance, opaque and lustreless: sculpture, numerous, close-set, and delicate spiral striae, which are only perceptible under a microscope: colour whitish : spire raised; whorls 3| ; the last is tumid and takes up three fourths of the shell; apex slightly twisted : suture deep: mouth roundish-oval; the peristome is not disjoined from the pillar, although complete and partly attached to it: umbilicus very small. L. 0*065, B. 0*05. 'Porcupiue' Exp. 1870 : Atl. St. 16. A single specimen. 13. CYCLOSTREMA SPHEROIDES, (spharoidea) S. V. Wood. Turbo spheroidea, S. V.Wood, Ann. & Mag. N. H . 1842, p. 533, pi. v. f. 3. 'Porcupine' Exp. 1870: Atl. St. 24, 26-28, 36, Tangier B. Several specimens. Bistribution. Bay of Biscay ('Travailleur' Exp. 1881). Fossil. Pliocene: Coralliue Crag, Sutton. Although minute, this is a very remarkable and beautiful species. It appears to be more scarce as a fossil than as recent or living. Tbe operculum has not yet been observed. Genus THARSIS2, Jeffreys. S H E L L globular, solid, and glossy: peristome circular and continuous, but attached to the pillar on that side : base closed by a pad or thick testaceous layer in the adult, perforated in the young : operculum chitinous or horny, and multispiral. This genus differs from Cyclostrema in the peristome being, although continuous, not free or detached from tbe rest of the shell, and in the umbilicus being closed instead of open in the adult. I do not consider it (as Seguenza supposed) Oxystele of Philippi, which is typified by Trochus merula ; in that genus the peristome is not continuous, and the pillar is sharply pointed or angulated at its base. THARSIS ROMETTENSIS, Seguenza. (Plate XIX. fig. 7.) Oxystele romettensis (Seg.), Granata-Grillo, Descr. de qu. esp. nouv. ou peu conn. 1877, p. 7. 'Porcupine' Exp. 1870: Atl. St. 16, 17, 17a, 24 ; Med. 45. 1 Shaped like a species of Bithynia. 2 One of tbe many synonyms of Cyprus. |