Several specimens, more or less perfect.This differs from any other species known to me in being devoid of sculpture, and in having a conspicuous umbilicus. 3. SCISSURELLA COSTATA, d'orbigny. S. costata, d'Orb. M h . SOC. d'hist. nat. de Paris, i. p. 344, ' Porcupine ' Exp. 1870 : Atl. St. Tangier B. Distribution. Throughout the Mediterranean and Adriatic, Madeira (Fatson), Teneriffe (McAndrew) ; 0-1 1 fnis. Fossil. Pliocene : Italy, Rhodes. 8. plicata aud 8. striatula, Philippi, besides several obsolete S. lawigata of d'Orbigny is apparently a variety. t. xxiii. f. 2.synonyms.

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Pecten fragilis*, Jeffr. SHELL roundish, equilateral, much compressed o1" flattened, excessively thin and brittle, of a paper-like consistency, semitransparent, rather glossy, and somewhat iridescent : sculpture, in the upper valve 15-20 concentric ribs or undulating folds, which do not extend to the sides, besides numerous longitudinal fine and raised stri~e, which latter radiate from the beak and cover the whole surface; the sides are otherwise marked by close-set lines of growth only; the lower valve has a few slight concentric ribs, but no longitudinal stri~e: eolour silvery-white: margins semicircular in front, and sloping gradually towards the hinge-line, below which on each side there is a gentle curve or depression: beaks very small and rather prominent: ears small but broad, equal in size, right-angled : hinge-llne straight : cartilaqe-pit very small, triangular : hlnge-plate broad and smoot}l : inside pearly :