ODOSTOMIA. 133 



colate, or creamcolour stained with madder : spire pyramidally 

 tapering ; nucleus exposed and lying in nearly a horizontal 

 position across the apex : ivhorls 8 (besides 2, which are em- 

 bryonic and reversed), flattened- the last occupies about one- 

 half of the shell : suture narrow, but excavated, sloping down- 

 wards in consequence of the peripheral keel : mouth rhomboidal, 

 contracted above, considerably expanded and angulated below; 

 its length somewhat exceeds a third of the whole spire : outer 

 Up obtuse-angled in the middle, and incurved just below the 

 periphery ; the inside or throat is finely but obscurely grooved 

 in the direction of the spire : mner lip slight on the upper part, 

 where it adheres to the pillar and joins the outer lip, reflected 

 and nearly straight on the lower part, the angle at the base 

 being very remarkable : umhilicus extremely small, and almost 

 covered by the lower part of the inner lip ; tooth strong, pro- 

 minent and conspicuous, placed opposite and behind the um- 

 bilicus ; it forms a sharp fold or ridge, which winds along the 

 pillar throughout the spire. L. 0-35. B. 0-15. 



Habitat : Coralline zone, off Whitburn, and Douglas 

 in the Isle of Man (Alder) ; Herm, on the shell-beach 

 (Metcalfe), and Guernsey, in 18-20 f. (J. Gr. J.) ; Larne, 

 CO. Antrim (Hyndman, fide Alder) ; Locli Fyne (A. 

 M'Nab) ; Aberdeenshii-e (Dawson) ; Shetland (Barlee). 

 Bohuslan (Loven in mus. Stockh., and Malm in mus. 

 Gottenb.) ; La Hougue Bay, Brittany (Mace) ; Lisbon 

 (M ^Andrew) ; Gulf of Lyons (Martin) ; Spezzia, in 

 10-12 f. (J. G. J.) j Adriatic (Nardo) ; Sardinia and 

 Naples (Tiberi). 



By far the largest and rarest species in this section ; 

 it deserves its specific name. Independently of size, the 

 whorls are less compact than in 0. acuta, the keel is 

 stronger, the mouth squarish, and the umbilicus reduced 

 almost to nothing. 



It is the 0. unidentata of Hanley, in Thorpe^s ' British 

 Marine Conchology.'' Malm mistook for this species an 

 old and imperfect specimen of the next. 



