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Show 698 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [June 7, Distribution. Falmouth, and St. Magnus Bay in Shetland ; single valves (J. G. J.); Algiers (Joly), a perfect and living specimen I Fossil. Pliocene: Coralline Crag, and variety as M. cyhndnca {Wood)!; Fiume Oreto, Sicily (Brugnone) ! Allied to 31. suBstriata ; perhaps viviparous and quasi-parasitic or commensal, like that species. Mr. Wood proposed the generic name Sphenalia for these and similar species. 5. MONTACUTA SUBSTRIATA, Montagu. Ligula suBstriata, Mont. Test. Brit. Suppl. p. 25. M. suBstriata, B. C. ii. p. 205 ; v. p. 177, pi. xxxi. f. 6. ' Lightning ' Exp. St. 2. 'Porcupine' Exp. 1869: St. 3, 10, 13, 14, 23c, North Channel. 1870: Mediterranean, off Rinaldo's Chair. Distribution. Finmark to the Mediterranean and Adriatic; 2- 250 fms. Fossil. Pliocene and Post-tertiary : Norway, Coralline Crag, and Italy. Inhabits the ventral spines of many kinds of Echimdae. The fry is almost globular, like that of Kellia suborbicidaris ; and the beak is placed in the middle of the dorsal area. There are several obsolete synonyms. 6. MONTACUTA BIDENTATA, Montagu. Mya Bidentata, Mont. Test. Brit. p. 44, t. 26. f. 5. Montacuta Bidentata, B. C. ii. p. 208, pi. v. f. 1 ; v. p. 177, pi. xxxi. f. 8. 'Porcupine' Exp. 1869: St. 2, 9, 16, 17, 18, 185, 19, Lough Swilly. 1870: Atlantic, 2, 13, 16, 17ff, off Cape Sagres, 26, 30; Mediterranean, Algesiras Bay, 50, 55, G. Bona, Adventure Bank. HistriBution. Finmark and Faroe Isles to the Mediterranean, Adriatic and Archipelago, and Madeira; shore-100 fms. Fossil. Pliocene and Post-tertiary : Norway, Sweden, Great Britain and Ireland, Belgium, and Italy; 0-130 ft. Not M Bidentata of Gould, which is 31. elevata of Stimpson. Nor is M truncata of S. V. Wood (as I once supposed) a variety of the present species, although they are closely allied. 31. elliplica, of the last-named author, appears to be a variety. Among the synonyms are Arcinella la?vis of Philippi and 3Iesodesma exiguum of Loven. In some specimens the layers of growth are so strongly marked as to form ridges. 7. MONTACUTA OVATA1, Jeffreys. (Plate LXI. fig. 4.) S H E L L triangularly round, with a somewhat oblique outline, rather convex, moderately solid, lustreless : sculpture none, except irregular lines of growth : colour whitish : epidermis inconspicuous: margins abruptly truncate at the smaller or posterior side, distinctly curved in front, elevated and rounded on the anterior side : Beaks small, inflected, with a deep indentation below; they are placed close to the 1 Oval. |