266 PYRAMIDELLIDiE. 



divide it from the latter : its volutional increase is more 

 rapid than in either. 



" Animal spiral, bluish hyaline white, inhabiting a white 

 shell of seven or eight flattish volutions, mantle simple, and 

 even with the shell. Head a subcylindrical muzzle occa- 

 sionally extended beyond the foot, bearing short broad 

 awl-shaped setose blunt tentacula, whose bases coalesce 

 and form a membranous veil, between which and the 

 foot the head issues; they have a fine transparent line 

 through their centres ; the eyes are within the internal 

 bases, close together, sunken in the surface-skin of the con- 

 necting tentacular membrane. The foot is short, truncate, 

 slightly auricled, but not in the least emarginate in front 

 as in 0. acuta, or even hollowed out as in 0. Eulimoides, 

 rounding gradually posteriorly, and sloping to a broad 

 obtuse lance-shaped termination, and has on the posterior 

 part of the upper lobe, which is simple, a light coloured 

 corneous suboval striated operculum ; the anterior under 

 part of the foot is flake white, the posterior is hyaline, 

 with a fine longitudinal line in the centre of that portion 

 of it. This species would scarcely be distinguished from 

 0. acuta, if it were not that the anterior part is not 

 in the least emarginate, and the tentacula are rather 

 stronger and broader than in that species. Branchial 

 plume I The habitat is amongst the masses of An- 

 nelida, and other animals, congregated in old oyster 

 shells, in the coralline zone. The animal is lively, and 

 permits without difficulty a free examination of its organs." 

 — Clark MSS. 



Its range of depth appears to be considerable, it is taken 

 occasionally from the rocks in Torbay and elsewhere 

 (S. H.). We believe it to be an abundantly diffused 

 species ; at Tenby and Oban it is particularly plentiful 



