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Show 566 MR, E. A. SMITH ON SHELLS FROM WEST AFRICA. [Nov. 15, 2. Notes on three Species of Shells from the Rio del Rey, Cameroons. By EDGAR A. SMITH. [Received June 30, 1887.] The shells here remarked upon form part of zoological collections recently sent to this country by Mr. H. H. Johnston, H.B.M. Vice-Consul for the Cameroons. ENNEA (PTYCHOTREMA) CYATHOSTOMA, Pfr. This species has only been previously recorded from Old Calabar, somewhat to the north-west of the Rio del Rey. Specimens from the two localities offer no differences. MELANIA FRETHII, Gray. The series of specimens in the British Museum and those from the Rio del Rey show that this species varies considerably in form, colour, and sculpture. The typical form (Griffith's Anim. Kingd. vol. xii. pl. 14. fig. 2), from Fernando Po, appears to be identical with M. nigritina, Morelet, found at Gaboon and ^Calabar. M. guineensis of Reeve I also believe to be a smoother form of this species ; for although stated by Reeve to be " destitute of any striated or shagreened sculpture," the surface is in fact minutely granosely striated, but much more finely than in the type of M. frethii. The M. fcenaria of Reeve is, as suggested by Brot, merely a light-coloured variety, the paleness in a great measure being due to the fact that the outer earthy deposit has been removed from the figured shell (Reeve, Conch. Icon. f. 134). The " zone of reddish rust " described by the author encircles the upper part of the whorls and is frequently visible within the aperture. None of the specimens sent by Mr. Johnston are full-grown, and some are very slender, but they all ageee in having three dark bands, clearly seen within the mouth, which would probably become less conspicuous when the shells arrived at maturity. NERITINA OWENIANA, Wood. Nerita oweniana, Wood, Index Test. Suppl. p. 25, pl. 8. fig. 8. Neritina oweniana, Martens, Conch.-Cab. ed. 2, pp. 75, 276, 278, pl. 9. figs. 14-17. The only locality previously recorded for this species is the island of Fernando Po, which is situated practically in the same re°-ion as the Rio del Rey, being only some twenty'or thirty miles from the mouth of that river. This shell is usually described as reticulated with black; but among the specimens received from Mr. Johnston are a few which, although reticulated throughout, show distinct transverse dark and lighter zones. The colour of the enamel which overspreads the columellar region varies from an almost uniform reddish tint to |
