190 PLlOCEiXE MOLLUSCA. 



most apparent at the base of the shell ; suture deep ; uiouth oval, augulatecl above ; 

 canal short, open, notched. 



Dimensions. — L. 14 mm. B. 6 mm. 



Distribution. — Coralline Crag: Boyton (probably elsewhere hi the Crag-). 



Remarks. — The charming little shell here figured from the Sedgwick Museum 

 at Cambridge was found at Boyton. It may have been taken at other Crag loca- 

 lities for a young specimen of some larger species. It appears a distinct form, 

 belonging to the same group as /S\ httenceus, though possibly it may be a variety 

 of the latter. 



Sipho tortuosus (Reeve). Plate XXIII, figs. 10—13. 



1855. Fusus tortuosus, Reeve, Belcher's Last Arct. Voy., vol. ii, p. 394, pi. xxxii, fig. 5. 

 1876. Sipho tortuosus, Kobelt, Jahrb. Deutscb. Malak. Gresellsch., vol. iii, p. 72, pi. ii, fig. 2. 



1881. Neplunea tortuosa, Kobelt, Martini mul Chemnitz, Couch. Cab., ed. 2, vol. iii (Pvu-puraeese), 

 p. 84, pi. XX vi, fig. 4. 



1878. Sipho tortuosus, G. O. Sars, Moll. Reg. Arct. Norv., p. 272, pi. xv, fig. 4. 



1882. Neptunea (Siphonorhls) turrifa, Friele, Norske Nordh. Exped. (Mollusea), pt. i, p. 20, pi. ii, 

 figs. 24—27. 



1887. Neptunea tortuosa, Kobelt, Icon, schalentrag. europ. Meerescouch., vol i, p. 76, pi. xii, figs. 



7,8. 

 1912. Sipho (Turrisipho) tortt(.osus, DAutzenherg et Fischer, Camp. Scient. Pr. Monaco, vol. xxxvii 



(Mollusques), p. 98, pi. iv, figs. 1, 2. 



Specific Characters. — Shell rather thin, .slender, elongate, fusiform ; whorls 

 more or less convex, the last rather abruptly contracted towards the base ; 

 ornamented with exceedingly fine and regular thread-like spiral lines ; apex obtuse, 

 planorboid;^ suture distinct; mouth ovate, acutely angulate above, ending abruptly 

 in a rather long, narrow, semitubular, and irregularly tortuous or twisted canal ; 

 outer lip thin ; columella flexuous. 



Dhuensions. — L. 45 mm. B. 15 mm. ... 



Distnl)ution. — Recent: circumpolar: Iceland, Finmark, Lofoten Lslands; dredged 

 off the Norwegian coasts from (32° lat. as far north as the Varanger fiord, and near 

 Spitzbergen, from 127 to 649 fathoms (Friele); Russian Lapland, Siberia, Green- 

 land, Alaska. 



PussiJ : Coralline Crag : Gedgrave. Waltonian : Little Oakley. 



Remarlcs. — A certain amount of confusion exists, among Crag geologists at least, 

 as to the identification of the Crag shells which have been referred to S. tortuosus. 

 Dr. Sparre Schneider, however, has kindly sent me a Recent specimen which he 

 considers the type-form of this species. After examining it and those in Prof. 



1 Morch proposed the term Siphonorhis as a sub-genus for Sipho-Yike shells having a depressed or 

 planorboid nucleus ; as stated below some authorities doubt whether this distinction can be always 

 relied on. 



