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Show 1890.] MARINE MOLLUSCA OF ST. HELENA. 271 lines also form two or three spiral bands. The thickened border of the umbilicus is not stained with brown so distinctly as in N. alderi. The operculum is at present unknown. NATICA (POLINICES) PORCELLANA, d'Orbigny. Hab. Teneriffe, Madeira, Cape Verde Islands. This species and N. uberina of the same author from the West Indies are very closely related, but the majority of specimens of the latter have a differently formed callus. The figure in Sagra's ' Hist. Cuba' (pi. xvii. fig. 19) represents an umbilical callus very like that of N. porcellana, but in most West-Indian specimens it has not got such a central prominence at the termination of tbe umbilical ridge, and consequently a less marked sinus above it. All the specimens from St. Helena are much smaller than the type figured by d'Orbigny (Webb & Berthelot's Hist. Nat. Canaries, Mollusques, pi. vi. figs. 27, 28). The umbilicus also in these specimens is unusually large, the groove within it deep, and the curved ridge is rather sharp. In the specimen of N. porcellana figured by Reeve (Conch. Icon. figs. 102 a, b) the umbilicus is much narrower and the callosity more developed. In the Museum Collection there are two specimens from Goree, named N. loveni, Dunker, which undoubtedly belong to this species, but at present I have not met with any description of that species. The operculum is thin, horny, and reddish. In bis list of St. Helena shells Jeffreys quotes N. nitida, Donovan. We did not receive this shell from Mr. Melliss; but it is possible it may have been the present species, which is not unlike Donovan's figure. IANTHINA COMMUNIS, Lamarck. Hab. East and West Atlantic. This species appears in Jeffreys's list of Mr. Melliss's St. Helena shells under the name of I. fragilis. The form and colour varies considerably in the seven specimens from the shores of St. Helena. Some are as depressed as /. cceruleata, Reeve (Conch. Icon. figs. 7a, 7b), and similarly coloured, whilst others are much more elevated, nearly as high in the spire as I. africana, Reeve, fig. 8 a, b, and white above as in that species, which is also considered but a variety of the present species by Sowerby (Thesaurus, v. p. 56). I. bicolor, Lesson l, also described and figured from St. Helena specimens, belongs to this species. IANTHINA GLOBOSA, Swainson. Hab. St. Helena (Lesson). This species is described and figured by Lesson, from examples taken at St. Helena, under the name of /. prolong ata, Blainville (vide Voy. Coquille, Zool. vol. ii. p. 366). 1 Zool. Voy. Coquille, vol. ii. p. 365. 19* |