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Show 1873.] MR. R.B.WATSON ON MADEIRAN MOLLUSKS. 367 Sh. M. 6. 5. 4. 3. 2. 1. L. ..*117 *045 -05 *026 *018 -Oil *007 *006 B. ..*063 -034 -051 *056 *045 -03 *019 *011 Hab. Gorgulho, shore ; Santa Cruz, shore ; Selvagens, shore ; Pontade Sao Lourenc;o, shore to 45 fathoms ; Piedade (Canical), 15 to 35 fathoms ; Funchal Bay, up to 50 fathoms ; Porto Santo, up to 50 fathoms. M y specimens from the Selvagens, given me by the Baron de Paiva, are very large and strongly tubercled from the strength of the longitudinal and spiral threads. I strongly suspect that this is the same species as Signor Manzoni's R. calathus from the Canaries and Madeira. That certainly has teeth within the lip and is somewhat stumpier in form ; but these are both variable characters; and in spite of the somewhat rubbed and bleached condition of the specimens (from Tenerife) of Manzoni's species, which I owe to the kindness of Mr. M'Andrew, I have recognized the characteristic markings on the embryonic shell as identical with those of m y species. That this species, at least, is distinct from R. calathus is a view in which I am supported by the opinion both of Mr. Gwyn Jeffreys and of the Baron Schwartz v. Mohrenstern. The two species have certainly some points of superficial resemblance, but differ in form, in texture, in colour, in threading both longitudinal and spiral, in the shape, make, and colour of the pillar, whole shape of mouth, constitution of outer-lip margin, and in markings of embryonic tip (?). I have named the species after m y friend Mr. Thomas Leacock, who has done much for the study of the Madeiran land-mollusks. RISSOA CANCELLATA, da Costa. (Plate XXXIV. fig. 2.) In M'Andrew's list. Hab. Gorgulho, shore; Ribeiro secco, 10 fathoms; Santa Cruz, 10 to 15 fathoms ; Machico, 10 to 15 fathoms ; Piedade (Canical), 15 to 35 fathoms ; Ponta de Sao Lourenco, 25 to 45 fathoms ; Porto da Cruz, 50 fathoms; Porto Santo, 50 fathoms; Funchal Bay, 50 fathoms. A European, Mediterranean, and Canary species. The Madeiran form of this shell is smaller than the British, and the whorls are more angulated. The teeth within the mouth are fewer by a half than the number given for them by Mr. Gwyn Jeffreys (vol. iv. p. 9, Brit. Conchology) ; but this is a feature of very little specific value. RISSOA AURANTIACA, Watson. (Plate XXXIV. fig. 3.) Shell oblong, thick, not transparent, a little glossy, tubercled, rising in steps. Sculpture, longitudinal ribs, on body-whorl 18 to 20, gently rounded, disappearing on base ; diminishing in number upwards on the whorls, and absent on the embryonic whorl; each is about twice as broad as the interval between them. |