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Show 1873.] MR. R. B.WATSON ON MADEIRAN MOLLUSKS. 373 (Journ. de Conch. 1868, pl. x. fig 1) has, on the whole, fairly caught the general character of this shell. The really bad features of the figure are:-the mouth, which fails to give the angulation at the junction of the pillar and the tip at the extreme base; the lip, which is represented as bevelled from the interior of the mouth outwards to the outside of the shell, whereas it is the inner margin of the lip which projects as a flange ; and the spire, which is made to form an almost perfect cone instead of rising strongly in steps in consequence of the depth of the suture and the angular droop of each whorl below the suture. I here subjoin Rissoa spreta as a mere variety of R. macandrewi. I have long held it to be a different species; and the two can be unfailingly distinguished, there being no connecting links. The general shape, the surface-sculpture, the form of the suture, of the apex, and of the pillar present slight differences; but the really strong points of distinction are the fosse on the base, the rounded swell of the whorls out of the suture, the more perfectly oval mouth without angulation on the base, and the absence of the distinctively white mouth and base. Beyond doubt it has a better claim to specific recognition than very many received species; and I am far from convinced that it will not ultimately be accepted as a distinct species. At the same time, after very careful study of a large number of these specimens, I do not feel quite certain that it really is a distinct species ; and where any doubt exists it ought to weigh on the side of suppression, any thing being better than a multiplication of false species. Mr. Gwyn Jeffreys, too, holds m y R. spreta for a mere variety of R. macandrewi; and what is, with me, stronger than all, I fail to find any difference in the embryonic whorls ; and identity m the earliest development must outweigh much later diversity. Var. SPRETA, Watson. (Plate XXXIV. fig. 9.) Hab. Santa Cruz, 10-15 fathoms; Machico, 10-15 fathoms; Piedade (Canigal), 10-15 fathoms; Ponta de S. Lourenco, 25-50 fathoms ; Porto Santo, up to 50 fathoms. This variety has some resemblance to R. crispa, but is not so hunchy, its spiral threads are not so close, the spiral striolations are not nearly so distinct, the spiral furrows and threads on the base are not nearly so strong, the longitudinal ribs are more numerous, not so sharp-topped, not so curved ; above all, these ribs do not cross the suture to lap up on the previous whorl. The mouth lies more straight in the line of the shell's length. RISSOA MONIZIANA, Watson. (Plate XXXIV. fig. 10.) Shell conic-oval, thinnish, not glossy, frosted, transparent; whorls rising in steps. Sculpture. Longitudinal ribs very rarely present on penultimate whorl, indistinct, rather irregular, narrow; somewhat oftener they appear on body-whorl very indistinctly below the suture, and even extend below the periphery, but generally, when seen at all, resemble faint irregular puckerings close below the suture. Labial rib is |