MACTRA. 361 



drew and E. F.) ; in three to four fathoms, Clew-bay, and 

 elsewhere in the west of Ireland (W. Thompson, R. Ball, 

 and E. F.) ; in fifteen fathoms, Moray Firth (M'Andrevv), 

 and twenty-seven fathoms, eight miles from land, off 

 Dartmouth (M' Andrew and E. F.) ; in twenty-four fa- 

 thoms, off Norfolk (Stanley) ; and very common generally 

 in deej} water, North Sea (Thomas). " A large, and much 

 produced variety is very common in the Ardrossan sands 

 in Ayrshire; a similar, but smaller one, is also common in 

 Lamlash-bay, Isle of Arran, where it is gathered alive at 

 low water, to feed pigs " (Alder). 



It ranges from the Mediterranean to the south of Nor- 

 way, and appeared in the Celtic seas during the epoch of 

 the red crag, living there through the glacial period. 



* We transcribe from the " Illustrations of the Recent Conchology of G. Bri- 

 tain and Ireland" (p. 108) the following description, which we have reason to 

 believe is merely that of an aberrant variety of M, suhlruncata ; the original shell, 

 now in the collection of Sir W. Jardine, was not accessible up to the time of the 

 printing of this sheet. 



" M. striata, (pi. 41, f. 10,) Brown. 



" Shell transversely elongated, rather strong ; umbones small, subcentral ; 

 anterior side subdepressed, and rounded ; posterior side elongated, and subovate : 

 its superior line gently arcuated, as well as the basal margin ; surface brownish 

 yellow, covered with strong tranverse equidistant stria; ; inside smooth, white. 



This species bears a strong similitude to M. subtruncata, but differs in the pos- 

 terior side being less acute, the nmbones being much smaller in proportion to the 

 size of the shell, in the striae assuming nearly the character of ribs, and in the 

 shell being considerably larger. I procured this species in Lough Strangford, 

 county of Down, Ireland." 



3 A 



