Mussel and Cockle. 101 



(J. cor), wliicli is also a member of the Clam family, 

 and one of the most elegantly-shaped shells in the 

 whole range of Conchology. It is a native of the 

 Mediterranean and other seas of Europe, and has 

 been taken in deep water on the west coast of 

 Ireland. We complete this group with a represen- 

 tation of the curious Arcadce family, or Ark shells, 



as they are commonly called, because one of the 

 species was thought to resemble the ark built by 

 Noah. Mr* Swain son tells us that the animals of 

 these shells affix themselves to other bodies by a 

 particular muscle, which is protruded through the 

 gaping part of the valves ; they also adhere, when 

 young, by means of the bissiform epidermis, or 

 bissus-like outer skin: this species is a native of 

 the Atlantic Ocean and the seas of Europe. The 

 Antique Ark (A. antiqua) is very like the Common 

 Cockle, being of a white colour, and heart-shaped. 



