RISSOA GUERTNT. 020 



7i*. lineolata is said to be a fairly common MediterraiieaTi species, liaving a shoi-t 

 conical spire, with an enlarged, obtusely angnlated base and strong- longitudinal 

 costa?. These features are well shown in our own specimen from St. Erth and in 

 the one figured by Philippi {([.v.). 



Eissoa Guerini, Recluz. Plate LI, figs. 9, 10. 



1843. Bissoa Guerini, Recluz, Rev. zool. Soc. Cuv., p. 7. 



1844. Bissoa cosfulafa, Alder (not Wood), Aun. Mag. Nat. Hist., vol. xiii, p. 324, pi. viii, figs. 8, 9. 

 1853. Bissoa costulata, Forbes and Hanley, Brit. Moll., vol. iii, p. 103, pi. l.vxvii, figs. 4, 5. 



1859. Bissoa costulata, G. B. Sowerby, 111. lud. Brit. Shells, pi. xiii, fig. 19. 



1867—84. Bissoa costulata, Jeffreys, Brit. Concli., vol. iv, p. 35, 1867; vol. v, p. 208, pi. ixviii, fig. 1, 



1869 ; B. similis var., Proc. Zool. Soc. London, p. 117, 1884. 

 1878 — 84. Bissoa costulata, Monterosato, Enum. e Sinoii. Conch. Medit. (Grioru. Soe. Sci. Nat. Palermo, 



vol. xiii), Y>. 84, 1878; Apicularia Guerini, Nonieu. Gen. e Spec. Conch. Medit., p. 56, 1884. 

 1879. Bissoa costulata, S. V. WooJ, Mou. Crag Moll., 2ud Suppl., p. 29, pi. iv, fig. 23. 

 1884—98. Bissoa Guerini. Bucquoy, Dautzenberg et Dollfus, Moll. mar. Rouss., vol. i, p. 267, pi. 



xxxii, figs. 4, 5, 1884; vol. ii, p. 771, 1898. 

 1890. Bissoa costulata, Cams, Prod. Faun. Medit., vol. ii, p. 320. 

 1892. Bissoa costulata, A. Bell, Rep. Yorks. Phil. Soc, p. 63. 

 1892. Bissoa Guerini, Locard, Coq. mar. Cotes de France, p. 171, fig. 147. 

 1901. Bissoa Guerini var. costulata. Conch. Soc. List, Journ. of Conch., vol. x, p. 18, no. 336. 

 1913. Bissoa Guerini, Dautzenberg et Durouchoux, Feuille des Jeuues Natur., vol. xliv, p. 28, pi. ii, 



fig. 2. 



Specific Cliaracter^. — Shell fusiform, oblong, conical, somewhat spindle-shaped, 

 rather solid ; whorls 8, convex ; ornamented by strong and prominent longitudinal 

 ribs, 10 on the last whorl, and usually by fine spiral ridges in the interspaces, 

 disappearing on the last, but they are variable in strength and sometimes quite 

 obliterated; spire elongate, tapering to a fine point; suture well marked; mouth 

 oval, contracted and incurved above, strengthened by a rib or callus near the 

 mouth ; inner lip reflected on the pillar and towards the base. 



Dimensions. — L, 5 — 6 mm. B. 2 — 2*5 mm. 



Distribution.. — Becent : Channel islands, southern and western coasts of England 

 and Ireland, Scarborough. Atlantic coasts of France and S[)ain. Mediterranean. 

 Fossil: St. Erth. Coralline Crag : Sutton. Selsey. Estuarine 

 clays of Belfast, Portrush. 



B.emarks. — The specimens from St. Erth and Selsey here represented seem to 

 agree very closely with Alder's original figure of R. costulata, but not with the 

 R. costulata of Risso, which Jeffreys says is the B. costata of Desmarest. The 

 authors of the Memoir on the Marine Mollusca of Rousillon in their first volume 

 identify Alder's shell with R. Guerini oi Recluz, of which the Conchological Society 

 considers it a variety. Jeffreys, however, regards it as a varietal form of R. similis, 



82 



