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Show 930 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [NOV. 29, ralline and Red Crag, S. France and Italy. Post-tertiary: Hopton in Suffolk and Calabria. 1. LYONSIA NORVEGICA, Chemnitz. Mya norvegica, Chemn. Conch.-Cab. x. p. 345, t. 170. f. 1647, 1648. L. norvegica, B. C. iii. p. 29, pi. ii. f. 1 ; v. p. 190, pi. xlviii. f. 2. 'Porcupine' Exp. 1869: St. 1,10, 14, 18, 23a, 35, 68. 1870: Med. G. Bona, Benzert Road, Rasel Amoush. DistriBution. Loffoden I. to theiEgean and Adriatic, and (according to Dr. Philip Carpenter), Seniavine Straits in the North Pacific; 2-162 fms. Fossil. Pliocene: Sicily. Not L. norvegica of Middendorff, which is L. arenosa, but probably Mya memBranacea of Gmelin from Miiller's ' Prodromus,' and Osteodesma infiatum of Danilo and Sandri. For other synonyms see 'British Conchology,' iii. pp. 31, 32. 2. LYONSIA FORMOSA1, Jeffreys. (Plate LXX. fig. 1.) S H E L L oval, equivalve, pearly, thin, and semitransparent: sculpture, numerous and close-set rows of minute tubercles, arranged lengthwise ; the posterior side is also marked with from six to eight diagonal flexuous ribs or folds, of which the innermost is the strongest and forms a keel; there are, besides, traces of other flexuous ribs in the middle and on the anterior side ; the posterior side has likewise a few rows of short but irregular prickles as well as the tubercles : colour silvery-white: epidermis filmy and only perceptible on the edges of the shell: margins rounded on the anterior side, gently curved in front, with a slight sinuosity and contraction towards the posterior side, which is somewhat truncated ; dorsal margin incurved on each side of the umbo: Beaks triangular, inclined to the anterior side: ossicle pearly, heart-shaped or notched at the posterior end : cartilage brownish-yellow, enclosing the ossicle; pit oval, with thickened edges : hinge-plate long and thick : inside highly polished and iridescent: muscular scars broad and distinct. L. 0*4, B.0*65. 'Porcupine' Exp. 1869 : St. 23. 1870: Atl. 3a; Med. 55. Distribution. 'Challenger' Exp. off Gomera, Canaries, 620 fms.; off Carysfort in the Gulf of Mexico {Pourtales), 349 fms. ; Bay of Biscay ('Travailleur' Exp.), 552-600 fms. A most lovely shell, and one of the prizes of the deep-sea dredger, who might be classed in the former part of Wordsworth's category as " They who rather dive than soar." 3. LYONSIA ARGENTEA2, Jeffreys. (Plate LXX. fig. 2.) S H E L L triangularly oval, rather solid, opaque, and of a dull hue: sculpture, a few slight ribs longitudinally radiating from the beak in the right valve, none in the other valve, which, however, is strength- 1 Beautiful. * Silverv. |