WAVERLY GROUP SPECIES. 305 



circle; hinge line very short, ranging nearly at right angles to the ver- 

 tical axis of the valves, and meeting the upper termination of the pos- 

 terior margin at, an obtuse angle; cardinal margins a little inflected, so 

 as to form a broad, shallow, corselet-like depression; beaks prominent, 

 gibbous, incurved nearly at right angles to the hinge, and located cen- 

 trally. Surface only showing obscure lines and a few somewhat stronger 

 marks of growth, excepting on the immediate umbones, where there are 

 small regularly disposed concentric wrinkles. Lunule moderately deep, 

 narrow subovate, and not distinctly defined. 



Length, 1.47 inches; height, 1.64 inches; convexity, about 1.33 inches. 



I know nothing of the hinge and interior of this shell, and merely 

 refer it to the genus Cardiomorpha from its similarity of form to some of 

 the short elevated and gibbous forms originally included in that genus 

 by its founder, DeKoninck. It agrees more nearly with the form he 

 refers to C. oblonga, Sowerby (sp.), than with any other with which I 

 have compared it, though its beaks are not near so strongly incurved or 

 spiral, and differ in being marked with small regular wrinkles. It is 

 also less gibbous, and does not have the margins of its valves meeting at 

 acute angles, as in that shell, nor does it show any traces of the large 

 concentric undulations seen on the same. 



Locality and position : Rushville, Ohio. Waverly group of Lower Ca,rboniferous. 

 Prof. Andrews's collection. 



Genus PROTHYRIS, Meek, 1869. 



(Proc. Acad., N. S., Philad., XXI, 172.) 



Prothyris Meeki, Winchell, ms. 



Plate 15, fig. 2. 



Prothyris Meeki, Winchell (1872) ; cited from his ms. in Hayden's Nebraska Report, 

 page 223. 



Shell transversely elongate-rhombic in outline, with height more than 

 one-third the length, rather convex ; basal margin long, nearly straight, 

 or sometimes faintly sinuous near or behind the middle; dorsal outline 

 short, straight, and sub-parallel to the base ; posterior extremity very 

 narrowly rounded and prominent below, and nearly straight, with a long, 

 very oblique slope above from the posterior end of the hinge; anterior 

 end quite short, moderately gaping, with its notch shallow and very 

 obtuse; beaks small, oblique, rising little above the hinge margin, rather 

 gibbous, and placed only about one-seventh the entire length from the 

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