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Show 1873.] MR. R. B.WATSON ON MADEIRAN MOLLUSKS. 389 RISSOA CORIACEA, Manzoni. (Plate XXXVI. fig. 27.) Hab. Santa Cruz, 10-15 fathoms; Machico, 10-15 fathoms; Piedade (Canigal), 25-35 fathoms; Ponta de S. Lourengo, 25-45 fathoms ; Funchal Bay, up to 50 fathoms. There are two pretty-well-marked varieties of this species, of which the one is larger in all its proportions, but distinctly longer relatively to breadth, with half a whorl more, thinner, more delicate, more contracted in lower part of each whorl. The other variety, from which Signor Manzoni's description and figure have been taken, is more frequent; it is a stumpier shell, with sometimes a tendency to a very slight thickening and rounding-over of the outer lip. Mr. Gwyn Jeffreys suggests that this should perhaps be classed under Fossarus. Signor Manzoni confesses the difficulty he felt as to its true place. It is certain that R. tenuisculpta and this species must go together, probably in the end to fall under a new genus, for the satisfactory establishment of which data are still wanting. RISSOA TENUISCULPTA, Watson. (Plate XXXVI. fig. 28.) Shell cylindrically oblong, thin, glossy, transparent, colourless. Sculpture. Longitudinal lines of growth few, faint, hair-like. Spiral scratchings about ^Vcr -*ncn apart, a little irregular and unequal, slightly fretted but not at all cancellated, very superficial, quite as distinct on the upper whorls as on the base. On embryonic whorl they are replaced by another set of spirals, about yinrij m c n apart and slightly deeper-seated (i. e. less on surface) and stronger. The point of junction of these two series is very faintly marked early in second whorl. Colour uniform yellowish white. Spire elongated, cylindrically conical, ending in a blunt jound tip, which is a little inverted. Whorls 5, probably 6 in fully adult shell, of very gradual and regular increase, very well rounded. Suture little oblique, deep, but open. Mouth a very perfect oval, only a little intrenched upon and flattened across the belly, and very slightly and bluntly pointed above ; open. Outer lip thin but not sharp, a very little separated from the body, with a slight tendency to form a sinus above, advancing and slightly expanded towards its outer lower corner, but not really channelled on the base. Inner lip sharp, a little advancing, so as to leave a very small umbilical chink, continued thinly across the belly, and projected a very little out from the body, so as to join the outer lip. Sh. M. 5. 4. 3. 2. 1. L *074 *029 *029 *018 012 *007 *006 B *034 *023 *023 *03 *022 *016 *011 Hab. Ponta de S. Lourengo, 25-45 fathoms ; Funchal Bay, up to 50 fathoms. Mr. Gwyn Jeffreys says that this is the same as one of the deep- |
