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Show 1873.] MR. R. B. WATSON ON MADEIRAN MOLLUSKS. 369 Hab. Gorgulho, shore ; Selvagens, shore ; Santa Cruz, shore to 15 fathoms; Machico, shore to 15 fathoms; Piedade (CaiiicA), 15 to 35 fathoms ; Pontade Sao Lourencu, 25 to 45 fathoms; Funchal Bay, up to 50 fathoms ; Porto Santo, up to 50 fathoms ; Teneriffe (fide Jeffreys, Brit. Con. vol. iv. p. 38). A coralline-crag, Arctic, Siberian, European, Mediterranean, Canary, and East North-American (fide J. G. Jeffreys, Ann. & Mag. Nat. Hist. 1872) species. Is this Madeira species really the R. striata of Adams 1 There is much to justify its elevation into a distinct species. It can be unfailingly distinguished by the strong basal threads. The difference between them, however, I have sought to mark by calling this var. lirata. There is a further variety existing equally among Madeiran and British forms of this species, which might be indicated by the var. called Candida by Brown; only this var. is not " devoid of the longitudinal ribs " as Candida is. It is more cylindrical, narrower, with whorls more fully rounded, and with a broader second whorl, and with a more spherical tip ; compared with this the typical form is more conical, with an outline less interrupted by the sutures, somewhat shorter in proportion to breadth, and narrowing upwards more equally to a small rounded but depressed apex. As in almost all species, a larger and a smaller form are also found. I owe m y Selvagens specimens to the kindness of the Baron de Paiva. RISSOA COSTATA, Adams. (Plate XXXIV. fig. 5.) Not in M'Andrew's list. Gorgulho, shore; Selvagens, shore; Santa Cruz, shore to 15 fathoms; Machico, shore to 15 fathoms; Piedade (Canical), 15 to 35 fathoms ; Ponta de S. Lourenco, 25 to 45 fathoms ; Funchal Bay, up to 50 fathoms ; Porto Santo, up to 50 fathoms ; Teneriffe, fide M'Andrew. A European, Baltic, Mediterranean, and Canary species. The embryonic whorl of this shell is not " quite smooth," but carries distinctly the spiral striae. The Madeiran form, like that (fide Jeffreys, B. Con. iv. p. 23) found at Spezzia and Tenerife, is very small. I owe m y Selvagens specimens to the Baron de Paiva. RISSOA CRISPA, Watson. (Plate XXXIV. fig. 6.) Shell conic-oval, whorls rising above each other in steps, solid, translucent, somewhat glossy. Sculpture: longitudinal ribs about 12, distant, narrow, ridge-like, not flexuous, but strongly bent from left to right; these become rather fewer upwards, and disappear on the first and second whorls ; they lap up on the preceding whorls (without adhering to them), and nearly conceal the suture. On the body they hardly stretch below the periphery, being cut off in a broadish furrow, which runs PROC. ZOOL. Soc-1873, No. XXIV. 24 |