BUBCINUM. 175 



in a comb-like manner ; shaft of the side tooth having three 

 notches, the lowest being the largest."* 



Arctic Ocean ; Siberia ; Sea of Ochotsk ; North Cape ; 

 Norway ; Baltic Sea ; England ; France, (Atlantic Coast) ; 

 Iceland; Labrador ; Newfoundland, southwards to New 

 Jersey ; Mediterranean Coast of France (exceptional). 



B. undatum being the t} r pical species of the genus, I have 

 deemed it advisable to copy the somewhat extended diagnosis of 

 the British specimens given by Jeffreys. I add his further re- 

 marks in order to complete the portraiture of the species : the 

 diverse conditions under which the varieties are found perhaps 

 sufficiently account for their existence. 



" Habitat : Every kind of ground, in all parts of the British 

 seas, from the shore to the greatest known depths. The first 

 variety is peculiar to hard ground in the coralline zone, through- 

 out the Hebrides, Orkneys and Shetland ; it is not common. 

 Second, among stones and on mud, in the higher part of the 

 laminarian zone, north of England, as well as Ireland, Scotland, 

 and Shetland. Third, brackish water at Southampton and Ips- 

 wich. Fourth, coralline zone of England, Wales and Ireland ; 

 not common. Fifth, Dogger bank ; Mr. Leckenby has a speci- 

 men six and one-half inches long. Sixth, soft ground in the deep- 

 water zone, west of Ireland, outer Hebrides, Orkneys and 

 Shetland ; I have a specimen of a pure white color. Besides 

 these, which I regard as the principal varieties, others have been 

 described by Professor King and Mr. A. Hancock. 



"In horticultural language, the species is very much given to 

 sporting. Every abnormal growth of the shell can be disting- 

 uished from those of a specific or varietal sort by examining the 

 apex or nucleus ; this will be seen to be regular, the malformation 

 having subsequently taken place, a,nd being in most instances 

 caused by some injury to the outer edge of the mantle. 



"The typical forin and variety striatum have been recorded 

 from every recent geological formation in the northern latitudes 

 of both hemispheres, and as far back as the Coralline Crag ; Pal- 

 ermo (Philippi). Mr. James Smith found the monstrosity 

 carinatum fossil at Bute, and Mr. Grainger at Belfast. 



* Jeffreys, Brit. Conch. IV, 285. 



