452 CONIDiE. 



The animal is white with a sHghtly yellowish tinge. 

 Its head is rather small with short teutacula, nearly two- 

 thirds of whose length is occupied by the thickened and 

 eye pedicles ; the terminal portion is subulate, and very 

 short. The foot is large, and capable of considerable 

 expansion, its anterior angles are obsoletely auriculated ; 

 its posterior extremity is broad, truncate, and often 

 emarginate. The caudal portion of the foot extends con- 

 siderably beyond the small ovato-pyriform operculum. The 

 siphon is very long, and is often extended considerably 

 beyond the head. 



This species is generally diffused all round the British 

 Islands ; so much so, that to enumerate localities would be 

 superfluous. It has a vast range in depth, extending from 

 the laminarian zone, where it occurs in three or four 

 fathoms water, to as deep as one hundred fathoms. This, 

 capacity for living under many bathymetrical conditions 

 corresponds with its tendency to variation. It is essentially 

 a northern shell, extending throughout tiie Arctic and 

 IJoreal seas, at both sides of the Atlantic, and a])parently 

 not ranging southwards beyond the Celtic region. It dates 

 its history in our seas from the red crag epoch. 



M. (Bela) Trevelliana, Turton. 



White; whorls bhuitly scalar; longitudinal riblets very small 

 and crowded ; body swollen ; a distinct labial sinus. 



Plate CXII. fig. 1,2. 



I'kurotoma sinuosa (not of Montagu), Fleming, Brit. Animals, p. ;j54 (from 

 type). 

 „ Trcvelliunum, Ti'rtun, Mag. Nat. Hist. vol. vii. p. .'{,j1. — Brit. 



Marine Conch, p. 197, f. ',2. 

 „ reiiculula, Drown, Illust. Conch. G. B. p. ii, pi. .5, f. "2.0, 30. 



,, decussaUc, Reeve, Conch. Iconica, vol. i. pi. 19, f. 159, as from type 



