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Show 1882.] 'LIGHTNING' AND 'PORCUPINE'EXPEDITIONS. 663 D. lobatum, G. B. Sowerby, jun., Thes. Conch. 1866, vol. iii. p. 100, fig. 44. ' Lightning' Exp., St. 1. ' Porcupine' Exp. 1869 : St. 19, 42, 89. 1870 : Atl. 17. Distribution. Arctic ocean from Spitzbergen and Novaia Zemblia to Finmark, 'Valorous' Exp., G. St. Lawrence to southern coast of New England ; 15-1750 fms. Fossil. Miocene: Vienna Basin (Homes) 1 Post-tertiarv : Norway, 82° 30' N. lat. (Feilden), Canada; 4-240 ft. Not Dentalium vitreum of O. G. Costa. DISCHIDES BIFISSUS, S. V. Wood. Dentalium bifissum, S. V. Wood, (Publ. Pal. Soc.) Crag Moll. i. p. 190, t. xx. f. 3, ab. ' Porcupine' Exp. 1870 : Atl. St. Vigo B., Setubal B.; Med. 50, 50a, Benzert Road, Adventure Bank. Distribution. G. Gascony, Mediterranean from Gibraltar to Sicily, Morocco, Canaries; 5-180 fms. Fossil. Pliocene : Coralline Crag, Italy. Post-tertiary : Selsea. B O D Y whitish, gelatinous: mantle rather thick, forming a collar round the front opening of the shell: captacula issuing from within the mantle, numerous, capable of so great an extension as to exceed the shell in length ; stalks very slender ; terminal bulbs oval: foot cylindrical and narrow, protruded from the middle of the mouth as from a sheath ; it is occasionally thrust out in a darting manner and suddenly withdrawn, and so swiftly that the point of the foot could not be observed ; the foot is usually curved towards the point: anal tube protruded beyond the narrower end or extremity of the shell; it consists of an outer and inner part, the latter being folded to suit the slit on each side : gills rather short, of a brownish colour. There are several useless synonyms. This species appears to be Dentalium coarctatum of Deshayes, but not of Lamarck. It was erroneously considered by me Dentalium olivi of Scacchi, for which see Cadulus. A species of Dischides, dredged by the late Admiral Sir E. Belcher in the North Pacific, somewhat resembles the present species, but is proportionally wider and the terminal slits are shorter and more open. The generic character of Dischides is the bilateral position of the terminal slits. Gadus bilabiatus and G. pa-risiensis of Deshayes, Eocene fossils, are not unlike D. bifissus in shape ; but the terminal point or base is jagged as in Siphodentalium vitreum, and the slit is much shorter. Besides, Gadus has been very long and notoriously used in Ichthyology. 1. CADULUS OLIVI, Scacchi. Dentalium olivi, Sc. Not. foss. Gravina (Ann. Civ. 1835), p. 56, t. 2. f. 6, a b. ' Porcupine' Exp. 1869 : St. 17. 1870 : Atl. 9. Distribution. Florb, Norway, a fragment (Norman), Bay of Biscay, Palermo (Monterosato), ' Valorous' Exp., New England (Verrill) 80-1450 fms. |