some neiv and peculiar Mollusca. 329 



coasts of United States, from low-water mark to 50 fms. 

 (Mighels and others) ! Spitzbergen (Torell) ! Iceland (Morcli, 

 Verlcriizen) ! Norway, 5-250 fms. (G. O. Sars and others) ! 

 ' Lightning' Expedition, 170 fms. ' Porcupine ' Expedition, 

 1869, oiFthe west of Ireland, 420 fms. ; north of the Hebri- 

 des, 203-345 fms. 



There are at least four varieties, viz. violacea of Mighels and 

 Adams (not of Hinds), and cylindracea^ Bechii^ and livida of 

 Moller (ex typ.), all published in 1842. P. Beckii of Reeve, 

 in Cuming's collection, is a very different and tropical species. 

 Specimens from 57 fathoms are of a pale colour, and those from 

 deeper water are white. Allied to the variety Livida is P. 

 gigas of Beck, which is Bela Icevigata of Dall, and probably 

 P. sdiantaricum of Middenclorff. Reeve renamed the present 

 species P. grcenlandica and P. rugidatus : he supposed that it 

 was the Defrancia suturalis and D. rugidata of Moller ; but 

 the latter gave no such names to any of his species. Appa- 

 rently not P. hicarinata of S. V. Wood. 



Pleurotoma rubescens, Jeffr. 



Holsteinborg, 10 fms. (a single but living specimen). 

 Described in Proc. Roy. Soc. vol. xxv. p. 183. 



Pleurotoma decussata, Couthouy. 



Pleurotoma decussata, Couth, in Boston Journ. Nat. Hist. ii. p. 183, 

 pi. iv. f. 8 (1839). 



Godhavn, 5-20 fms. ; Waigat Strait, 15-25 fms. ; Station 3, 

 100 fms. ; 5, 57 fms. Greenland (Moller, Morch) ! N.E. 

 America, from the Gulf of St. Lawrence to Ccipe Cod, 10- 

 64 fms. ' Porcupine ' Expedition, between the north of Scot- 

 land and the Faroes, 560 fms. 



I have now been able to ascertain that this species is the 

 same as Defrancia viridida of Moller (1842) ; and I was 

 therefore wrong in supposing that the latter was not American 

 (see Proc. Roy. Soc. vol. xxv. p. 189). It is the P. scalaris 

 and P. leucostoma of Reeve, who imagined tliat Vahl had de- 

 scribed them under the names of Defrancia scalaris and D. 

 reticulata ; but Vahl did nothing of the kind. I would not 

 have noticed Reeve's numerous mistakes if Morch had not 

 recognized his so-called species. 



Pleurotoma tenuicostata, M. Sars. 



Pleurotoma tenmcostata, Sars in Vid. Selsk. Forhandlinjrer for 18(38, 

 p. 259. 



Station 12, 1450 fms. Mjightning ' Expedition, 500 and 



