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Show 1890.] MARINE MOLLUSCA OF ST. HELENA. 293 In the Cumingian Collection there is a single specimen of this species and one of C. vicinum, which were received from Adams himself. On examination they seem to me to belong to one and the same species, the difference in thickness of the spiral and transverse ridges being very slight. Some of the St. Helena examples exceed the dimensions given by the author, having a length of 6 millimetres, and they consist of ten normal and three nuclear whorls. The slightly elevated spiral line mentioned by Adams is at the top of the whorls just below the suture, and the "fourth " spiral nodulous slender ridge on the body-whorl should have been termed the fifth. CERITHIOPSIS NEGLECTA (C. B. Adams). Cerithium neglectum, C. B. Adams, Panama Shells, p. 154. Hab. Panama (Adams) ; Algiers (Sowerby). This is a minute dark brown granulated shell, consisting of about twelve whorls, of which the three or four apical are transparent, glossv, smooth, and separated by a brown sutural line. Adams observes that there are two additional spiral ridges on the lower part of the body-whorl, whereas I distinctly count three, both in Panama and St. Helena specimens. With this exception, no fault can be found with his diagnosis. Sowerby's figures (Thesaurus Conch, pi. 184. figs. 235, 236) either represent another species, as each whorl has but two rows of granules, or else have been carelessly drawn. HIPPONYX ANTIQUATUS (Linne). Hab. West Indies, Fernando Noronha, island of Trinidad in the South Atlantic, and xlscension Island ; Loanda (Dunker). HIPPONYX GRAYANUS, Menke. Hab. West coast of Central America, Sandwich Islands, Fernando Noronha. I have given the distribution of this and the preceding species, also references and synonymy, in my account of the Mollusca of Fernando Noronha, which will be published in the Journal of the Linnean Society. TEINOSTOMA ? ABNORME. (Plate XXIV. fig. 5.) Testa minuta, alba, pellucida, subglobosa, imperforata; anfractus 3, rapide accrescentes, sutura canaliculata sejuncti anfract. ultimus magnus, minute spiraliter striatus, in regione umbilicali callo crasso instructus ; spira planet, hand elevata apertitra magna, ovata, inferne effusa; columella arcuata, callo crasso reflexo induta. Longit. 1 millim., diam. max. 1. Although so minute, the above measurements probably represent the adult size of this species. It does not agree with the typical forms of Teinostoma in the shape of the aperture; but in texture and colour it is very similar. |