pressed line; hinge line one half the height of the valves. Left valve 

 of same form, but the ears less distinctly separated; hinge line less 

 than one half the height, anterior ear with concave front outline. 

 The beaks are acute and moderately prominent. Surface marked 

 by numerous close, minute, concentric lines, and numerous irregular, 

 concentric wrinkles which give a peculiar appearance to the shell, 

 not shared by other species. These wrinkles are less marked on 

 young shells. There are also, in most cases, indications of radiating 

 lines, which in the larger shells are strong striae or ribs, at a distance 

 from each other." 



Remarks. This species appears in the Boggs limestone where it 

 is rare, but in the Lower Mercer horizon it constitutes a very abun- 

 dant and characteristic fossil, especially in the Flint Ridge region. 

 Herrick states that next to Entolium aviculatum Swallow it is the 

 most common bivalve at Flint Ridge, which statement in the ex- 

 perience of the writer is true. A specimen a little above average 

 size measures: length 20 mm., height 20.5 mm., length of hinge line 

 of right valve 11 mm. 



Horizon and locality. Boggs limestone: Blunt Run, Muskingum 

 County (Locality 27), r. Abundant and wide-spread in the Lower 

 Mercer limestone. 



Genus Euchondria Meek 

 Euchondria neglecta (Geinitz) 



1866 Pecten neglectus. Geinitz, Carb and Dyas in Nebr., p. 33, tab. 2, Fig. 17. 



Nebraska City, Nebraska. 

 1872 Avicnlopeden neglectus. Meek, U. S. Geol. Surv. Nebr., p. 193, PL 9, Figs, la, b. 



Upper Coal Measures: Nebraska City, Nebraska. 



Coal Measures: Illinois. 



Meek's description: "Shell very small, broad subovate exclusive 

 of ears, even thin, rather compressed; sides and base more or less 

 regularly rounded; cardinal margin shorter than breadth of valves. 

 Left valve (according to Professor Geinitz figure) with ears nearly 

 equal, the anterior o^e separated from the margin below by a broad, 

 very shallow sinus, and forming less than a right angle at its extremity; 

 posterior ear extending farther down the margin than the other, very 

 faintly sinuous behind, and forming an angle of about 100 at the 

 extremity. Right .valve with anterior ear narrow and rather acutely 

 angular, defined by a deep, narrow sinus, extending back about half 

 its length; posterior of about the same length, but of greater vertical 

 breadth than the other, rather pointed at the extremity and defined 

 by a moderately deep, broadly rounded sinus, and a subangular 

 umbonal slope. Surface of the body part of both valves apparently 

 only marked by fine concentric striae; ears with a few radiating costae, 

 crossed by fine striae and a few coarser marks of growth. 



Height and breadth each, 0.26 inch; length of hinge, 0.21 inch." 



SO 



