Qapers^ Piddocks, and Ship-worms 147 



The Faroe Sun.set-shell (P. ferroensis) is larger, 

 more opaque, and duller, marked with close low- 

 concentric ridges, which become higher just before 

 reaching the clearly marked 

 posterior slope, across which 

 they are very distinct. In that 

 particular region they are crossed 

 by half a dozen (on each valve) 



•^ . ., „ ^ Faroe Sunset-shell 



fine radiatnig ribs irom the beaks. 

 The shell is more or less covered by a dull greenish 

 epidermis, but where this is worn away the colour 

 is seen to be pink w^ith indefinite rays of a deeper 

 tint and small oval spots of white. The inside is 

 coloured with some shade of purple, and wery highly 

 polished. This is a common species on all our coasts, 

 in sand, at depths between 4 and 90 fathoms of 

 water. 



The large Sunset-shell (P. vespertinci), which is 

 the largest of the native species, is of a more oval 

 form. It is somewhat solid, compressed, and glossy 

 where the thick olive epidermis has worn off. 

 Where it is thus bared the shell is seen to be of 

 a yellowish-white hue with rays of purple-brown 

 or lilac. The sculpturing of the surface is very 

 slight, and has the appearance of having been worn 

 down; it consists of concentric ridges, and more 

 evident lines of growth, crossed by obscure radiating 

 lines. Interior coloured yellow or purple. The 

 animal is yellowish white in colour, with a fringed 

 mantle, and a broad thick foot. It is a local species, 

 but found widely distributed, chiefly on the south 

 and west coasts of both England and Ireland, and 

 on the west coast of Scotland. Like the others 



