180 TUKRITELLlDiE. 



left side of whieli at the dorsal point, may bo seen a 

 minute jiale red branchial leaflet. The neck did not 

 exhibit the slightest traces of external reproductive organs. 

 Foot short, narrow, and truncate anteriorly. Operculum 

 circular, corneous, black-brown, smooth and conical on the 

 surface, attached to the foot, concave without, and from 

 its centre seven or eight fine close-set spiral lines fill up 

 the area. The animal is not at all shy, it shows itself in 

 all directions, marches with great vivacity, carrying its 

 shell sometimes with the convexity upwards, resting on the 

 posterior point or on one of the sides, frequently changing 

 one for the other, by suddenly withdrawing the head and 

 body by which action it is thrown on the operculum at 

 an elevation of fifty or sixty degrees ; it then turns on 

 the side it wishes. (Clark.) Specimens forwarded alive 

 by their discoverer to London lived for several days in a 

 vial of sea-water, and exhibited all their features ; from 

 them we have taken our figures. 



Widely distributed, yet rare. Exmouth, in the coral- 

 line zone (Clark) ; Torbay (S. H.) ; Falmouth, Whitesand 

 Bay, Weymouth, Swansea Bay, Tenby, Loch Carron, in 

 Scotland, Bantry Bay, and Cork Harbour (Jeffreys). It 

 ranges to the Mediterranean. 



We have not cited the Orthocera trachea of Fleming, 

 (Brit. Anim. p. 237) which is described as a white shell, 

 having the rings regular and sharp in the young,* but 



* This agrees with two individuals thus named in Mr. Alder's collection 

 which, with his usual candour, he acknowledges to have received from a doubtful 

 quarter. They are transparent and snowy white, with moderately distant, keel- 

 like rings, some of which are sharp at the edge and others rounded. They do 

 not appear to be traversed by any regular longitudinal striulse either on the 

 annuli or their intervals. We have received tliis species, likewise, from Aden in 

 Arabia. 



