No. 109.] 



99 



Megan TERis ^quiradiata. 



Pal. N.Y. Vol. iii, pi. 45, f. 4. 



Jttrypa cequiradiata, Conrad : Jour. Acad. Nat. Sc. Phil., Yol. 8. p.266; 



pi. 16, f. 17. 



Shell elliptical or subovoid ; valves nearly equal ; surface marked 

 by simple regular radiating strise ; beak of the ventral valve 

 moderately incurved, scarcely gibbous ; margins of valves not 

 sinuous. 

 Geological position and locality. Upper Pentamerus limestone of the 



Lower Helderberg group, Schoharie. 



MSGANTEEIS .SIQTJIEADIATUS. 



Meganteris L^VIS. 



Pal. N.Y. Yol. iii, pi. 40, f. 2. 



Shell broad oval or subquadrate. not sinuate : ventral valve the 

 more convex, most prominent along the middle and towards the 

 beak, which is pointed and arched so as to rise above the hinge- 

 line, but not closely incurved j foramen narrow, extending quite 



