FAMILY ANATlNIDiE — ANATINA. 235 



GENUS ANATINA. Lamarck. 



Animal having the mantle closed by a wide membranous plate, with a small rounded 

 aperture on the antero-inferior portion, for the passage of a tongue-shaped foot. Two 

 elongated tubes separated for some considerable distance from their extremities ; the infe- 

 rior slightly longest. Branchiae narrow, free, and pointed behind. Shell usually thin, 

 sometimes translucent, fragile, ovate, rounded, nearly equivalve, inequilateral, gaping 

 slightly at one or both extremities'. Hinge with a prostrate spoon-shaped tooth in each 

 valve, to receive the cartilage ; and a small ossiculum resting in front of the teeth, usually 

 removed with the animal. 



Anatina papyracea. 



m PLATE XXXI. FIG. 300. 



(STATE COLLECTION.) 



Anatina papyracea. Say, Jour. Acad. Nat. Sc. Vol.2, p. 314. 

 A. id.fragilist Totten, Amer. Jour. Sc. Vol.28, p. 347, pi. I. 

 A, papyracea. Gould, Inrertebrata of Mass. p. 47, fig. 28. 



Description. Shell thin and fragile, ovate-rounded ; one valve more convex, and at the basal 

 margin projecting a little beyond the other. Beaks not prominent, in the posterior third of 

 the length of the shell : from the beaks to the posterior portion runs an elevated angular 

 ridge ; shorter end narrowed and subtruncated, slightly gaping. Surface of the valves mi- 

 nutely wrinkled. Tooth long, narrow and oblique, with an accessory process at the base. 

 Ossiculum like two crescents fitting in front of the teeth. Color, white and pearly. 



Vertical axis, 0*5; transverse ditto, 0*6. 



This delicate shell, which is rare, occurs along our whole coast. It has been obtained by 

 dredging at Newport, Rhode-Island, and from the stomachs of fishes on the coast of Massa- 

 chusetts. 



80* 



