PALJIOZOIC FOSSILS. 



Orthis oblata (B,ew species). 



Palaeontology of New-York, Vol. iii, pi. 10, f . 1 - 14. 



Shell ( in the young state) longitudinally subovate, and yarying 

 from circular to transversely oval in its stages of growth, re- 

 supinate : ventral valve convex at the beak, flattened in the 

 middle, and convex towards the front ; dorsal valve very convex 

 in the middle and towards the beak j beaks of the two valves, 

 nearly equally elevated,, that of the ventral valve pointed ; area 

 very small ; foramen large. Surface finely striated ; strise fre- 

 quently bifurcating and curving towards the lateral and cardinal 

 margins, concentrically marked by finer strige and stronger lines 

 of growth, which are numerous in the older shell. 



Locality. Helderberg mountains. 



Okthis oelata. 



