- 127' - 



Subgen'us Scapharca Gray. 

 Seotioii Scapharca s. s. 



ARGA (3GAPIIARGA) KAIIDOITATA Dall . 



Area oonsobrina Gupp;, 1866, Quart, Jour. Oeol. Soc . London, vol. 



22, p. 293 (non Sowerby, 1850). 

 Area oonsobrlna Guripy, 187^, Geol. Iv'as:. , Decade 2, vol. 1, p. 44.';, 



(check list) ex oarte, non Sower'by, 1850. 

 IJot A. consobrlna d'Orbifmy, 1844. 

 Scapharca f 3ca-oharca ) halidonata Dall, 1898, Trans. Wa^-ner Free 



Inst. 3ci., Philadelphia, vol. ?, pt. 4, pp. 646-647, 



pi. 55, fip". 24. 



Description .- "Shell sub equi valve, ovate, oblique, inflated; 

 bealrs rather high, strongly bent forward, almost reaching the int- 

 erior fourth of the length; left valve larger, with about thirty- 

 four clear-cut, elegci.tly sculptured radial ribs; the anterior 

 dozen ribs are usually dichotomous or deeply sulcate ; the ribs on 

 the middle of the shell are grooved nrith one or t\vo shallow, sharp, 

 incised lines; the more -oosterior ribs ere wider and flatter v/ith 

 three or more grooves; those on the posterior dorsal slope are 

 angiilar, narrower, and usually have not more than one groove, which 

 is nearly obsolete; the concentric sculpture is of evenly spaced, 

 fine, elevateri lines arched in the interspaces and finely nodulat- 



