108 Xeiv Species of Fossils from 0/u'u. 



eye-tubercle, as well as in its slightly dilfereiit position ; but 

 most distinctly in the sub-angular ridge-like node, and greater 

 convexity of the lower border of the valves. This projecting 

 node being situated near the lower margin, and also being the 

 most prominent j)oint of the valve, causes the rock to adhere to 

 the more abrupt sides when fractured, and gives to the valves 

 as they appear upon the fractured surface a very decidedly trian- 

 gular aspect, entirely unknown in L. alta. 



Formation and Locality. — In the hydraulic limestone of the 

 Lower Helderberg group, at Grcentield, Ohio, where it occurs 

 in great numbers, forming distinct layers through the rock, as 

 does the L. alta in the Tentaculite limestone of New York. 



Species from the Limestones of the Upper Helderberg Group. 



PROTOZOA. 

 ReceptacuSites Dcvoniciis, u. sp. 



Pal. O., Vol. Ill, Plate 2, Fig. 10. 



A very decidedly marked and characteristic specimen of the 

 genus Receptaculites, De France, has been obtained from the 

 limestones of the Upper Helderberg group, by Mr. Ed. Hyatt, 

 of the Ohio State University, from a quarry at Fishinger's mills, 

 about eleven miles north of Columbus, Ohio. The specimen is 

 about two and a half inches in diameter, is broadly concave 

 across the disc, and sliglitly recurved at the outer margin. The 

 concentric lines of i)ores or cells are strongly marked, and in- 

 crease rapidly in size as they recede from the centre of the dijc, 

 but the surface has been so macli weathered that the grooves 

 left by the removal of the stolons at the foot of the cells are not 

 distinguishable, so that the entire specific characters are not 

 recognized; enough, however, remains to show the general form 

 and proportions. It has much the appearance of specimens of a 

 corresponding size of B. Otveni, Hall, from the lead-hearing 

 limestones of the West, both in its general foi'm and in the con- 

 cavity of the disc, as well as in the proportions and rate of in- 

 crease of the cell-openings as seen exposed on the surface of the 

 limestone. 



The occurrence of a species of this genus at this liorizon, is a 



