MACTRA. 365 



teen of moderate tliough irregular lengths, the anal with 

 about sixteen or twenty finer, shorter, and more even ; 

 the colour of the tubes is pale brown, with a reddish 

 tinge. The foot is white, large, and thick, long and taper- 

 ing to a fine edge, and extensible into every form, from 

 a blunt mass to a very sharp lanceolate termination : it has 

 no byssal groove ; there are on each side two branchias 

 of a brown colour, the outer the smaller and overlapping the 

 under one very obliquely ; the latter is hung more trans- 

 versely from the dorsal portion of the body ; a pair of 

 labial palps are united on each side of the buccal orifice, 

 and hang from it in long, subtriangular, pointed leaflets 

 of a paler brown and marked with stronger striae, espe- 

 cially on their inner sides, than the branchiae." 



This is a most abundant shell everywhere on our sandy 

 beaches, littoral in its habits, and rarely taken by the 

 dredge except near shore and on a continuous tract of 

 sand, when, as off Ormeshead, it may be taken as deep 

 as twelve fathoms. As it ranges from one end to the 

 other of the British Isles with no restriction save unsuita- 

 bility of ground, to enumerate localities would be super- 

 fluous. 



It is distributed generally through the European seas 

 as far north as the south of Norway, where the long 

 range of rocky coasts and deep water of the west inter- 

 rupt its progress. Phillppi mentions it as a species col- 

 lected by Ehrenberg and Van Hemprich in the Red Sea. 

 As a fossil it occurs in the red and mammaliferous crags. 



