68 ANATINID^. 



Oentis COCHLODESIWA, Couthouy. 1839. 



Shell incquivalve, 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. Sc. vi. 263, pi. 11, fig. 11. 



Cochlodesma Leana, Couthouy, Bust. Jonra. Nat. Hist. ii. 170. — De Kay, Nat. Hist. 

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

 171. — MiGiiELS, Shells of Maine, Bost. 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 slightly 

 wrinkled ])y the lines of growth, some- 

 what pearly beneath ; interior chalky- 

 white, the muscular and palleal impres- 

 c. Leanum. sioiis supcrficial, pearly. The spoon-shaped 



hinge process nearly horizontal, directed 

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

 posterior muscular imj)rcssion, immediately in front of which is 

 another thread-like In-anch in the direction of the cleft in the beak. 

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

 inch nearly ; breadth, nine twentieths of an inch. 



Found about Cape Cod in almost every direction, inhabiting 

 sandy beaches ; also about 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 (Mig^hels') ; Nahant Beach, after a storm (^Haskell} ; 

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



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



