62 PROCEEDINGS OF THE ACADEMY OF 



arranged radiating and concentric lines, wliicli are larger and 

 more strongly defined in the anterior ear of the right valve, par- 

 ticularly the radiating markings, which there sometimes assume 

 the character of small costaj, while the concentric markings some- 

 times project as little lamellae slightly above the hinge-margin, so 

 as to give it a dented appearance. 



Height of one of the largest specimens seen, 1.32 inches; antero- 

 posterior diameter, 1.20 inches; convexity, about 0.18 inch. 



I know of no other shell in our rocks that is liable to be con- 

 founded with this, its general form and neatly cancellated mark- 

 ings being sufficient to distinguish it. Although I refer it provi- 

 sionally to Amculopecten^ I really do not think it belongs properl}^ 

 to that genus, as restricted to the typical forms. At least it 

 differs from all the characteristic forms o^ Amculopecten^ in having 

 the anterior ear larger than the posterior, as well as in having 

 its beaks placed a little behind the middle of the valves, thus 

 giving the slight backward obliquity mentioned in the descrip- 

 tion. This latter character seems to approximate it to Sfrebloj)- 

 teria of McCoy, but as we know nothing of its hinge and inte- 

 rior, it is not possible to determine whether it belongs to that 

 group. 



The specific name is given in honor of the Rev. H. Hertzer of 

 the Ohio Geological Survey, to whom I am indebted for the use 

 of some fine specimens from his own private collection. 



Locality and position. Newark, Ohio. Lower Coal-measures. 



LUCINA (PAKACYCLAS) OHIOENSIS, Meek. 



Shell apparently not attaining a medium size, compressed, 

 nearly circular ; beaks small, central, depressed nearly to the 

 dorsal line, and contiguous ; anterior margin rather abruptly 

 compressed above, just in front of the beaks; hinge-margin short 

 and rounding into the posterior dorsal outline ; surface orna- 

 mented with small, more or less regular concentric undulations 

 (most strongly defined on the umbones), and A'er^' fine lines of 

 growth; posterior dorsal slope of each valve marked by a strong 

 oblique sulcus, extending from the back part of the beaks to the 

 upper part of the posterior margin. 



Length, 0.46 inch; height, 0.42 inch; convexity, 0.18 inch. 



This species seems to be related to L. lirata (=^Posidoma lirata, 

 Conrad, Ann. Geol. Rept., N. Y., 1838, p. 116; and Thirteenth 



[June 6, 



