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Show 1873.] MR. R B. WATSON ON MADEIRAN MOLLUSKS. 385 Hab. Gorgulho, shore ; Santa Cruz, 10-15-fathoms; Machico, 10-15 fathoms; Piedade (Canigal), 15-35 fathoms; Ponta de S. Lourengo, 25-45 fathoms ; Porto Santo, up to 50 fathoms. This species extremely resembles R. pulcherrima, with which I at first associated it, till Mr. Gwyn Jeffreys's practised eye discerned the difference in some specimens I had sent him. The two are unquestionably different. They are most easily distinguished by the former being spotted, while this is banded ; but as I have two specimens of this species in which the bands have broken somewhat into spots, the rich chestnut stain at the centre of the base and on the belly-lip must be noted. Its difference from the little-known species R. cossurae, Calcara, specimens of which I owe to the kindness of the Marquis de Monterosato, requires particular notice. Put together, they cannot be confounded ; of nearly the same size, they differ very much in form. R. cossurae is comparatively small in the base and last whorl, minute in mouth, stumpy in spire and apex, second and third whorls broad, all the whorls closely rolled together; its colour is crimson, not chestnut. The central spot on base and belly-lip is much larger in R. cossurae; the spiral scratches on the whorls are more distinct; there are no sharp frettings below the suture. On the embryonic whorls I failed to distinguish any microscopic lines, which in R. perminima are easily seen. R. cossurae (if the mouth be excepted) suggests a minute R. cingillus, while R. perminima approaches R. pulcherrima. Compared with R. fulgida, which in colour it somewhat resembles, this is much longer and narrower. The whorls are not nearly so rounded; suture not at all deep ; spire attenuated ; apex more pointed ; mouth not round, but oval and pointed above ; and there is an umbilical chink. Mr. Gwyn Jeffreys regards this species as the R. perminima of Manzoni. RISSOA ABJECTA, Watson. (Plate XXXVI. fig. 23.) Shell conic-oblong, small, white, opaque, rather strong, with complete peristome. Sculpture. Longitudinal lines of growth a little bent, microscopic, with here and there a line somewhat stronger than the rest. Spiral frettings minutely microscopic, very faint and superficial. The first two whorls, which are embryonic, seem to have a few spiral lines or scratches. Colour opaque yellowish or creamyish white, quite uniform except that the embryonic whorls are rather yellower. Whorls 5-6, flattened, but slightly rounded, with a very faint tendency to angularity below. The two embryonic whorls are very markedly smaller than the third, out of the middle of which they rise as a little cone, which seems to be truncated in consequence of the excessive minuteness of the extreme tip. Suture rather straight, thread-like, slightly channelled. Mouth oval, smallish, scarcely contracted on the belly, slightly pointed above. Outer lip gently rounded, not patulous, sharp but not thin. PROC. ZOOL. Soc-1873, No. XXV. 25 |