DESCRIPTION OF SPECIES 197 



even after due allowance is made for natural variation in shape, the 

 differences noted between Meek's and Herrick's specimens appear too 

 great for individuals of the same species. Typical S. anodontoides has 

 the cardinal and basal margins strongly converging anteriorly, with the 

 anterior extremity acutely and prominently projecting. In Herrick's 

 form, on the other hand, the cardinal and basal margins are subparallel, 

 and the anterior extremity is broadly rounded and less prominent. No 

 specimens comparable to typical S. anodontoides have been found even 

 in Meek's type locality on Flint Ridge, so that in the absence of ma- 

 terial for comparison Herrick's identification is provisionally retained, 

 although it is the opinion of the writer that the form here referred to 

 S. anodontoides really constitutes a distinct species. 



Horizon and locality. Lower Mercer limestone: Perry County, 

 Locality 35, r; Muskingum County, Locality 43, r. 



Edmondia aspinwallensis Meek 

 PI. X, fig. 7 



1871 Edmondia aspinwallensis. Meek, Prelim. Kept. IT. S. Geol. Surv. Wyoming 

 p. 299. 

 Upper Coal Measures: Aspin wall, Nebraska. 



Description. Edmondia aspinwallensis is present in the middle 

 and upper Potts ville formation. It resembles most closely the form 

 here referred to E. ovata } but differs in being shorter in comparison to 

 the height with a shorter dorsal margin, and in having a narrower 

 posterior extremity, and slightly more elevated beaks. The concentric 

 surface markings are likewise finer and more regular and faint traces of 

 radial sculpture are sometimes retained. 



Horizon and locality. Lower Mercer limestone : Muskingum 

 County, Localities 43 (r), 45 (c); Licking County, Localities 46 (c), 

 Flint Ridge, 47 (c). McArthur limestone: Vinton County, Locality 84, c. 



Edmondia gibbosa (McCoy) 

 PI. X, figs. 4, 5 



1844 Astarte gibbosa. McCoy, Syn. Garb. Foss. Ireland, p. 55, PI. VIII, Fig. 11. 



Carboniferous: Ireland. 

 1866 Astarte gibbosa. Geinitz, Die Garb, und Dyas in Nebr., p. 16, Tab. 1, Figs. 23, 24. 



Carboniferous: Plattsmouth, Nebraska. 



Description. A form of Edmondia which is in very close agreement 

 with the species from Nebraska figured and described by Geinitz as 

 Astarte gibbosa, is rather common in the Lower Mercer and McArthur 

 limestones. It is small, subcircular or slightly transversely ovate in 



