360 PLEUROTQMATID.E. 



G. J., M 'Andrew and Forbes, and Barlee) ; Orkneys 

 (Thomas, fide F. & H.). Finmark (Loven); Christian- 

 sund, 30-40 f. (Lilljeborg); Upper Norway (M f Andrew 

 and Barrett). 



It is variable in size. We do not know the exact 

 position, in a generic point of view, of this delicate little 

 shell. In 1841 I named it Fusus albus. The Pleurotoma 

 nanum of Scacchi is a very different species. Our shell 

 is allied to C. Holbollii ; but that has a small shield-like 

 operculum, and is longitudinally ribbed at the top. 



The last-named species is one of our glacial fossils ; 

 it has been dredged by Mr. Waller, Mr. Hyndman, and 

 myself on the Turbot bank, co. Antrim, in 20-25 f., by 

 Mr. Norman and myself in the Hebrides, at a depth of 

 60 f., and by Mr. Dawson off the Aberdeenshire coast. 

 I found it also in the Fort William deposit. It inhabits 

 every part of the Arctic seas, from Bergen, northwards, 

 and the United States. The late Professor Gould de- 

 scribed it as Buccinum rosaceum. This species was 

 erroneously placed by Morch in the genus Mitrella (as 

 " Mitsella ") of Bisso. 



Family XXX. PLEUROTOMATID^E, (Pleu- 



rotomacea) Loven. 



Body spiral, more or less elongated : mantle forming a short 

 fold above the head for excretal purposes, the fold occupying 

 a fissure or notch in the outer lip of the shell : pallial tube not 

 protruded much beyond the canal of the shell : head small : 

 proboscis retractile : tentacles placed far apart, with slender 

 points : eyes on the extremity of stalks, which are conj oined 

 with the lower portion of the tentacles, and placed outside 

 them : foot lanceolate, double-edged in front, with a pointed 

 tail : gills arranged in two unequal- sized plumes : odontophore 

 having no central tooth [" rhachis edentula," Loven] ; pleurae 



