252 LUCINID/E. 



soalpture, irregular lines of growth and intermediate micro- 

 scopical striae: colour reddish-brown outside, and milk-white 

 inside the crust: epidermis thin and obscured by the outer 

 covering : margins rounded on the anterior side and in front, 

 obliquely truncate or sloping on the posterior side, which is 

 slightly nexuous and marked by a broad but shallow furrow 

 radiating from the beak, as in the last species : beaks small 

 and tubercular, rather prominent, much recurved, not so close 

 together as in A. flexuosus, and nearer to the anterior side: 

 lunule imperfectly defined : corselet indistinct : ligament short, 

 reddish-brown, sunk within the lips of the corselet and hardly 

 visible outside ; ligamental groove very slight and narrow : 

 hinge-line obtusely angular, deeply excavated in the centre 

 on the posterior side of the beak, and occupying about one- 

 third of the circumference : hinge-plate narrow and sharp, 

 reflected and projecting below the beak on the anterior side, so 

 that the edge appears like a blunt cardinal tooth ; by far the 

 greater part of the hinge-plate lies on the posterior side : inside 

 rather glossy ; margin plain : pallial scar slight, entire : mus- 

 cular scars conspicuous and round. L. 0'125. B. 0*125. 



Habitat : Muddy ground and sand in 30-50 fathoms, 

 Sound of Skye; 20-100 fathoms, Loch Fyne ; and 70- 

 80 fathoms, off the west coast of Shetland. Close to 

 Crouiin Island, in the first of these localities, it is 

 remarkably plentiful. Captain Hoskyn has lately taken 

 specimens off the west coast of Ireland at a depth of 

 210 fathoms. Glacial beds, Aberdeenshire (Jamieson); 

 Coralline Crag, Sutton (S.Wood). Torell has dredged it 

 in 250 fathoms off the coast of Greenland ; Loven and 

 other writers have mentioned it in their lists as Scan- 

 dinavian, from Finmark to Bohuslan ; and Forbes first 

 described it, as inhabiting the ^Egean at a depth of 119 

 fathoms. 



The young are oval and transparent. Some speci- 

 mens of a larger size than usual have a snout-like 

 process which projects from the angle of the posterior 

 side, and is caused by an excessive accumulation of the 

 ferruginous crust in that part. This induces me to 



