1882.] 'lightning' AND 'porcupine' EXPEDITIONS. 663 



D. lohatum, 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) ? Post-tertiarv : Nor- 

 way, 82° 30' N, lat. (Feilden), Canada; 4-240 ft. 



Not Dentalium vitreum of O. G. Costa. 



'' Dischides bifissits, S. V. Wood. 



Dentalium bifissum, S. V. Wood, (Publ. Pal. Soc.) Crag Moll. i. 

 p. 190, t. 5x. f. 3, a-b. 



' Porcupine' Exp. 1870 : Atl. St. Vigo B., Setubal B. ; Med. 50, 

 SOff, 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. 



Body 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 and suddenly withdrawn, and so swiftly that the point of the foot 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 b\' 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- 

 risie?isis of Deshayes, Eocene fossils, are not unlike D. bifssus 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 iu Ichthyology. 



l^ 1. Cadulus olivi, Scacchi. 



Dentalium olivi, Sc. Not. foss. Gravina (Ann. Civ. 1835), p. 56, 

 t. 2. f. 6, ab. 



' Porcupine' Exp. 1869 : St. 17. 1870 : Atl. 9. 



Distribution. Floro, Norway, a fragment {Norman), Bay of Bisca)', 

 Palermo (Monterosato), ' Valorous ' Exp., New England (Verrill) ; 

 80-1450 fms. 



