1883.] 'lightning' AND '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. Speci- 

 mens very numerous. 



Bistributio7i. Josephine Bank, Bay of Biscay (' Travailleur ' Exp. 

 1881), Palermo (Monterosato); 103-913 fms. 



Ditters from C. simile in shape, as well as in the raised spire and 

 narrow umbilicus. 



1/ 12. Cyclostrema BiTHYNOiDEs', Jeffreys. (Plate XIX. fig. C.) 

 Shell oval, thin, having a somewhat frosty appearance, opaque 

 and lustreless : sculpture, numerous, close-set, and delicate spiral 

 strife, which are only perceptible under a microscope : colour 

 whitish : spire raised ; lohorls 3g ; 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. 0065, B. 005. 



'Porcupine' Exp. 18/0 : Atl. St. IG. A single specimen. 



\/ 13. Cyclostrema SPHEROIDES, {sphceroideo) 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. 



Distribution. Bay of Biscay ('Travailleur' Exp. 1881). 



Fossil. Pliocene : Coralline 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. 

 The operculum has not yet been observed. 



Genus Tharsis", Jeffreys. 



Shell globular, solid, and glossy : peristome circular and con- 

 tinuous, 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 cliitinous or horny, and multispiral. 



This genus differs from Cyclostrema in the peristome being, 

 although continuous, not free or detached from the 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. 



1^ 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, 17ff, 24 ; Med. 45. 



' Shaped like a species of Bifhynia. 



" One of the many synonyms of Cyprus. 



