CONCHIPERA. 



323 



attached to dead bivalve shells and coral, at the depth of 

 eleven fathoms in the Gulf of Dulce, in Costa Rica, Cen 

 tral America. It is intermediate, as its name denotes, 

 between Placuna and Anomia: the hinge is like the 

 former, and the opening in the lower valve for the passage 

 of the tendon causes its resemblance to the latter. 



Anomia. Lin. — Shell inequivalve, more or less irre- 

 gular, attached to rocks &c. by a calcareous mass affixed 

 to the adductor muscle, which passes 

 through a hole in the lower valve, the 

 latter being small, and nearly flat ; 

 bosses very small, no teeth, ligament 

 short and thick. Animal shaped like 

 the shell, mantle freely open, with pen- Anomia epMppium. 

 dent margins, bearing a double fringe 

 of short cirrhi ; no conspicuous ocelli ; no siphonal tubes ; 

 body massive ; foot very small, often nearly obsolete ; 

 adductor muscle divided into three portions, the longest 

 passing through the notch in the lower valve, and attached 

 to the opercular piece, partly attached to the inner surfaces 

 of the shell ; branchial leaflets doubled on themselves ; .. 

 mouth surrounded by membranous borders, and two pair 

 of long labial tentacles striated on both sides.*— 17 spe- 

 cies f ; also fossil. 



From the Mediterranean and other European seas ; also 

 the seas of America, the Moluccas, Philippines, &c. It 

 is found adhering to shells, rocks, and other substances, 

 and takes the irregular form of the surface to which it is 

 attached ; so that if fixed to a Pecten, it will be striated. 

 It cannot be detached without destroying the animal, and 

 the calcareous mass by which the shell is attached is so 



* Forbes's British Moll. f Gray's Sinopsis of Brit. Museum. 



y 2 



