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Show 712 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [June 7, A. crebricostata, B. C. ii. p. 319 : v. p. 183 : G.O. Sars, Moll. reg. arct. Norv. t. 5. f. 7, a, b. 'Porcupine' Exp. 1869 : St. The Minch (semifossil). Distribution. Arctic seas from Tromsd northwards, Siberian coast, N.E. America from Maine northwards, 'Fox' Exp., 'Valorous' Exp., Norwegian arctic Exp., Dutch arctic Exp. ; 5-500 fms. Fossil. Post-tertiary: Great Britain, Scandinavia, Siberia; 10- 1360 ft. Syn. Crassina depressa, Brown, A. crebricostata, Forbes, A. cre- Brilirata, S. Wood (young), A. richardsoni, Reeve, A. lens, Stimpson MS. May be known by its depressed and triangular shape and its numerous ribs ; but I have specimens which seem to unite it with A. sulcata. The typical form is smaller, inclined to oblong, and more convex. Variable to some extent. Of two fossil valves from Bridlington of the same size one is plain edged, and the other has the inner margin notched. 4. ASTARTE COMPRESSA, Montagu. Venus compressa, Mont. Test. Brit. Suppl. p. 43, t. 26. f. 1. A. compressa, B. C. ii. p. 315 ; v. p. 183, pi. xxxvii. f. 3, 4. 'Porcupine' Exp. 1869 : St. LochToiridon (var. warhami, semi-fossil). 1870: C. Sagres (var. semistriata, valves). DistriBution. N. Atlantic from Spitzbergen and Novaya Zemblia to the Dogger Bank and N e w England, Vancouver I. {P. Carpenter, as A. compacta) 1 The typical form is arctic, Scandinavian, Hebri-deau, and N. American ; the variety globosa is also arctic; var. striata is arctic and northern, but reaches the Yorkshire coast. 3-2000 fms. Fossil. Upper Tertiaries, and more especially Post-tertiary: Siberia, Scandinavia, G. Britain and Ireland, N.E. America (mostly var. striata), Nice (Bisso, as Gyprina montagui) 1 ; 0-1360 ft. Not less variable than A. sulcata, and consequently having many synonyms. The typical or smooth form is Nicania Banksii of Leach. M y variety gloBosa is not Mbller's species of that name, but agrees with a specimen from the collection of the late Mr. Albany Hancock, which was named by him A. warhami. The A. sulcata of Gould (fig. 45) represents this last variety. 5. ASTARTE TRIANGULARIS, Montagu. Mactra triangularis, Mont. Test. Brit. p. 90, t. 3. f. 5. A. triangularis, B. C. ii. p. 318; v. p. 183, pi. xxxvii. f. 5. 'Porcupine' Exp. 1870: Atl. St. Vigo B., C. Sagres, 26, 36; Med. Algesiras B„ Cartagena B., 50, Benzert Road, Adventure Bank (var. subtrigona.) Distribution. Shetland to G. Egina, Adriatic, Canaries (var. par-vula) ; 0-205 fms. Fossil. Upper Tertiaries: British Isles, Belgium, Vienna Basin, S.W. France, Italy. Post-tertiary : Norway. Calabria. Synonyms several. " Gregarious in fine shelly sand at low water |