708 



NORTH AMERICAN INDEX FOSSILS. 



342. E. arata Conrad. (Fig. 10 19.) Eocenic. 

 Oblong-ovate, slit large but not deep, on [narrower end ; apex 



central, strongly incurved ; surface with angular ridges, largest on 

 posterior (broad) end and increasing by intercalation or division. 

 Claibornian of Alabama, rare. 



343. E. marylandica Martin. (Fig. 1020.) Miocenic. 



Fig. 1 01 9. Emarginula arata. 

 (After Conrad.) 



Fig. 1020. Emarginula mary- 

 landica. (Md. Survey.) 



Smaller than preceding and more nearly oval, beak nearer the 

 posterior end, radiating ridges round, uniform on all parts of shell, 

 distant with smaller ones between. 



Choptank formation of Maryland. 



XCIX. Fissuridea Swains. (Fissurella in part of authors.) 



Subconical or subcapuliform shells of oval base and the apex 

 anterior to the middle and replaced by a perforation with a callus 

 on the interior. Carbonic (?)-Recent. 

 344. F. griscombi (Conrad). (Fig. 1021, a-d.) Miocenic. 



Fig. 1021. a-d, Fissuridea griscombi, a, b, X %» c t d, young, X 5 > e if-> F> marylna- 

 dica, X %• (Md. Survey.) 



Young with enrolled protoconch, later resorbed by advancing 

 fissure ; moderately high, subconical laterally compressed surface, 

 plicae strong, alternating, generally two or three finer ones be- 

 tween two coarser. 



Chesapeakean of Maryland and New Jersey. 



