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Show 1873.] MR. R. B. WATSON ON MADEIRAN MOLLUSKS. 363 what oblique, descending towards the mouth-corner from the whole last quarter of the body-whorl. Mouth bluish white, with a narrow dirty yellowish edge. In form small, deep, very slightly patulous: in the depth of the throat perfectly oval, but towards the outside angulated; this angulation is at the upper corner slight, but at the shoulder of the whorl more distinct. The mouth thus resembles an irregular bowl of a spoon, of which the canal forms the shank. Exclusive of the canal, it is rather more than one third of tbe shell's length (i.e. as 8 to 22). Canal long, narrow, deep, and slightly excavated in under the left side; but its lips are not at all contracted. In its course it is scarcely curved; but in its general direction it bends a little to the left. It ends in a semicircular notch. It is not at all recurved. Outer lip angulated, sharp, narrow, but strong ; internally quite smooth ; not at all reflected, but a little patulous. It leaves the body in a very straight, but slightly retreating line ; where it meets the line of the first spiral ridge it turns angularly downwards with a very slight curving in towards the line of the shell's axis; just below the lowest ridge it again alters (slightly) its direction, so as to run more longitudinally and straight along the side of the canal : just at the extreme point it swells a very little outwards. Inner lip quite smooth, expanded as a thickish glaze on the belly ; it sweeps round there with a perfect oval curve. At exactly half its length it is deserted by the great fold of the base which encircles the umbilicus : from this point it still for 4_ inch pursues the same direction to the beginning of the canal; there it turns sharply, and throughout the rest of its course runs in slightly towards the axis of the shell, overhanging the canal. Its edge all along the umbilicus is very sharp. Pillar broad above, below cut off diagonally so as to expose to the fullest the enormous circular umbilicus, which is almost as large as the mouth, and which extends up into the heart of the shell; it is lined throughout with the epidermis ; within, it can be seen coiling spirally upwards, the thick margin slightly marked by the old ends of the canal. Operculum thick, horny, black, and claw-like; nucleus at the lower point; surface scored from side to side with numerous slight concentric lines. Its interior side is polished, with many slight concentric lines on its inner margin and on its central flat, and with a broad, thick, rounded border extending from its apex along its outer margin. It is perfectly represented in all respects by the picture in Adams's ' Genera,' pl. xvi. fig. 4, a, b, except that, as seems generally the case in that work, it is turned upside down. Canal Sh. M. (leftside) 7. 6. 5. 4. 3. 2. 1. L...2-2 1-2 '37 1*2 *45 *27 *17 *1 *05 *03 B.,.1-1 *55 *14 *61 1* *63 *38 *18 *1 *05 Of this mollusk I have found (besides an unmistakable and perfectly fresh fragment broken off by the dredge, in Funchal Bay) |