22 



arched plate below it. Length, including the umbo, fourteen lines ; exclud- 

 ing the umbo, twelve lines ; width, thirteen lines. 



Loeality and Formation. — Indian Cove, Gaspe Bay. Gasp^ lime» 

 stone. No. 8. 



Collector.— R. Bell. 



Strophomena magniventka. (Hall.) 



PI. 2, figs. 2, 2a. 



Strophodonta Magniventra. (Hall.) Tenth N. Y. Reg. Rep., p. 54, 1857. Pal., N. Y., vol 



IIL. p. 411, pi. 92 and 95. 



Description. — Shell rather above the medium size, semi-elliptical; car- 

 dinal angles about 90^ ; sides, in the posterior half, nearly straight or 

 slightly concave ; all of the anterior half uniformly rounded. Width on 

 the hinge line from one to two inches and a half, usually about two inches. 

 Length from three-fourths to five-eighths of the width. 



Ventral valve usually strongly and uniformly convex, with the excep- 

 tion of the cardinal angles, which are more or less compressed. Some 

 specimens are only slightly convex. Beak small, scarcely distinct from 

 the edge of the area. On a side view the outline is strongly curved, most 

 abruptly so from the beak over the umbo. (Fig. 2a.) The area is large, 

 not flat, but more or less concave ; when perfect, nearly smooth or with a 

 few longitudinal strise, (parallel to the hinge line). When the surface of 

 the area is exfohated or slightly worn, the vertical or dental strise come 

 into view. The edge of the area is denticulated throughout its whole 

 length. Deltidium flat, smooth, triangular, its base about equal in length 



Fig. 10. Fig. 11. 



Fig. 10. Cast of the interior of the ventral valve of ^S". magniventra from the Oriskany 

 sandstone, c. cast of the small umbonial cavity ; d^d, casts of the divaricator 

 muscular scars; o, o, casts of the occlusors; t, small tubercles which are the 

 casts of the two small pits occupied by the extremities of the divaricator pro- 

 cesses. 



Fig. 11. Cast of the interior of the ventral valve from the Gaspe limestone. Letters, 

 same as fig. 10. 



