282 CARDIID^. 



Var. 1. globosa. Shell more globular, the posterior side 

 being less produced. 



Yar. 2. alba. Shell milk-white, of an intermediate shape 

 between that of the typical kind and the first variety. 



Habitat : Gravelly sand, in 5-90 fathoms, from Shet- 

 land to the Channel Isles, generally diffused and rather 

 common. Var. 1. Shetland and west coast of Scotland. 

 Var. 2. Off Unst in deep water, together with coloured 

 specimens. In a fossil state this species occurs in the 

 Clyde beds at Bute (Smith) ; Coralline Crag (J. G. J.). 

 Its foreign range extends from Iceland (S teens trup and 

 Torell), Faroe Isles (Morch), Norway and Sweden 

 (Loven, Sars, and others), Bay of Kiel (Meyer and 

 Mobius), Zealand (Hsellebsek), Cannes (Mace), Spezzia 

 in 18 fathoms (J. G. J.), Gulf of Tunis, Malaga, and 

 Canary Isles (M'Andrew), to the Azores (H. Drouet). 

 In Finmark it acquires a comparatively enormous size. 

 It is one of the Uddevalla fossils. 



This shell is never sharply angular like C. exiguum, 

 and it is of a much thinner substance. In the young 

 the prickles are vaulted, and cover the ribs in the same 

 way as brick tiles are set on the crest of a roof. The 

 fry are almost flat, and have a square contour. They 

 may be distinguished in this state from C. exiguwn by 

 having more ribs. Mr. Clark observed a specimen to 

 be full of ova on the 4th of August. 



Owing to the posterior side being more produced in 

 some specimens than in others, Montagu seems to have 

 made two species out of this one, viz. C. elongatum and 

 C. fasciatum. The former represents the more usual or 

 typical kind. I have a shell which was sent by Mr. 

 Dillwyn to Col. Montagu for his opinion, and' returned 

 with the name " Car. fasciatum " in the handwriting of 

 the latter on the cover of the small packet which still 



