68 ANATINIDiE. 



Oenus COCHLODESMA, Couthouy. 1839. 



Shell inequivalve, inequilateral, slightly gaping at both ends ; 

 beaks small, cloven ; hinge a spoon-shaped process in each valve, 

 supported by an oblique rib, and receiving the cartilage. 



Cochlodesma Leanum. 



Figs. 29, 30. 



Shell thin, white, sub-oval, the shorter side of the right or more convex valve 

 truncated ; rib-like support directed backwards. 



Anatina Leana, Conrad, Journ. Acad. Nat. So. vi. 263, pi. 11, fig. 11. 



Cochlodesma Leana, Couthouy, Best. Joura. Nat. Hist. ii. 170. — De Kay, Nat. Hist. 

 New York, 236, pi. 31, figs. 299, 301. — Ciiexu, Man. de Conch, ii. 38, figs. 170, 

 171. — MiGHELS, Shells of Maine, Best. Journ. Nat. Hist. iv. 315. 



Cochlodesma Leanum, Stimpson, Shells of New England, 22. 



Shell sub-oval, thin and brittle, white, with a thin, yellowish epi- 

 dermis ; the right valve convex, and truncated at the shorter end ; 

 the left valve nearly flat, and rounded at both ends ; posterior end 



gaping, a little the shorter, and usually a 

 '"■  little the narrower ; beaks very small, 



scarcely prominent, cleft at one side ; a 

 faint, wave-like ridge passes from them to 

 the lower posterior angle ; surface sliglitly 

 wrinkled by the lines of growth, some- 

 what pearly beneath ; interior chalky- 

 white, the muscular and palleal impres- 

 a~L>^^m. sions superficial, pearly. The spoon-shaped 



hinge process nearly horizontal, directed 

 across the shell, and resting on a rib-like support, directed to the 

 posterior muscular impression, immediately in front of which is 

 another thread-like branch in the direction of the cleft in the Ijeak. 

 Ossiculum none. Length, one and two fifths inches ; height, one 

 inch nearly ; breadth, nine twentieths of an inch. 



Found aljout Cape Cod in almost every direction, inhabiting 

 sandy beaches ; also aliout Nantucket, I have never heard of it 

 on the north shore of Massachusetts Bay, but it is more abundant 

 to the south of us. From Casco Bay southward (^Stimpson) ; near 

 Portland (Mi<rheh') ; Nahant Beach, after a storm (^Haskell) ; 

 Chelsea Beach (^Monds) ; Fishing Banks (^WilUs^. 



The animal has the mantle closed in front, except an opening 



