SECTION III. 



LAMELLIBEANCHIATA FEOM THE LOWER MAEL BEDS. 



Order ASIPHONIDA. 



Suborder MUNOMYAEIA. 



Family OSTEEID^. 



Genus OSTEEA Linn. 



Ostrea denticulifera. 



Plate III, Figs. 8 and 9. 



Ostrea denticulifera Conrad. J. A. K Sci., Phil., 2d ser., Vol. Ill, p. 30, PL XXXIV, 

 Figs. 1 and 8. Gabb, Synop., p. 152. Meek, Check-list,p.6. Geol. Surv 

 X. J., 18CS, p. 724. 



The shells of this species are very small, flattened, thick, and extremely 

 irregular in form. Those originally described by the author seem to have 

 been moderately convex, but the New Jerse}^ specimens are extremely 

 shallow and generally elongated, with the surface obsoletely striate ; even 

 on the smoothest specimens the strife show beneath the surface. The liga- 

 mental area is small and the margin crenulate on some individuals to near 

 the front of the shell, the crenulations being strong and tooth-like, and leav- 

 ing ridges on the sides of the valves as the shells thicken with age. Muscu- 

 lar impression large, lateral, and usually below the middle of the length. 



All the specimens of this species observed are iipjier valves; no lower 

 valves appear to have been collected. Mr. Conrad, in his original descrip- 

 tion, mentions only "lower valve moderately capacious; upper margins 

 denticulated," features which might have been inferred. 



Formatiou and locality. — The specimens used are from the collection of 

 the Academy Natural Science, Philadelphia, and are marked Haddonfield, 

 New Jersey, and are probably Mr. Conrad's types. I have not observed it 

 in other collections. 



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