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Show 1885.] 'LIGHTNING' A N D 'PORCUPINE' EXPEDITIONS. 55 Distribution. Off Sahara, C. Verd I., and Azores (' Talisman' Exp.); 681-1261 fms. This elegant shell is closely allied to Cerithiella whiteavesii of Verrill, from the coast of New England, and may be the same species. 5. CERITHIUM OBELISCOIDES1, Jeffreys. (Plate VI. figs. 4, 4 a.) S H E L L pyramidal, rather thin, semitransparent, and glossy: sculpture, more or less numerous fine and rounded longitudinal striae, which are crossed by a few spiral striae : of the latter there are 5 or 6 on the last whorl, 4 or 5 on the penultimate, and 3 or 4 on the following three or four whorls ; the second whorl is marked by close-set and more curved longitudinal striae ; the top whorl is quite smooth, as well as the base of the shell; the intersection of the two sets of striae gives a reticulated but not a decidedly nodulous appearance ; a considerable space below the suture in each whorl has the longitudinal striae only : colour milk-white: spire gradually tapering to a very blunt point: whorls 7-9, convex; the last is equal to two fifths of the spire in length ; the first whorl is bulbous, and in some specimens is larger and broader than the succeeding whorl: suture rather deep, defined by the lowest and thread-like of the spiral striae : mouth as in the other species of this section, but smaller and with a shorter groove : outer lip thin, scalloped : inner lip inconspicuous : pillar flexuous. L. 0*175, B. 0*05. Some imperfect specimens show that this species attains a comparatively much greater size. 'Porcupine' Exp. 1870: Atl. St. 16, 17, 17a. 6. CERITHIUM CYLINDRATUM2, Jeffreys. (Plate VI. figs. 5, 5a.) S H E L L rather cylindrical, thick, opaque, lustreless : sculpture, numerous straight longitudinal striae, which are crossed by fewer and finer spiral thread-like striae, so as to present a reticulated appearance and to make the points of intersection tuberous or scabrous ; the spiral stria? are 4 on the last whorl, besides a basal line below the periphery, and 3 on each of the preceding whorls; the second, and sometimes also the third, whorl is marked with close-set and curved longitudinal striae ; the first whorl is quite smooth and glossv : colour pale yellowish-brown : spire gradually tapering to a blunt point: whorls 10-12, rounded but compressed ; the last equals about one third of the length of the shell ; the first is bulbous and like that of the last species: suture narrow but distinct : mouth as in all the foregoing species : outer lip thickish and prickly : inner lip filmy : pillar flexuous. L 02, B. 0-075. 'Porcupine' Exp. 1870: Atl. St. 27-30, 36; Med. Benzert Road, Basel Amoush, Adventure Bank. This has somewhat the aspect of Cerithiopsis tubercularis, but the apex and mouth are those of a typical Cerithium. 1 Like an obelisk. 2 Cylindrical. |
