BBA.CHIOPODS. 47 



usually referred to Sowerby's form. Bat inasmuch as the 

 synonymy of the epecies is still unsettled it does not appear ad- 

 visable to propose a new term for the American P. muricatus. 



Productus cora D'ORBIGXY. 

 Plate xxx vii, figs. 2a-c. 



Productus cora d'Orbigny. 1843 : Voyage dans P Amerique Meridionale. 

 Productus cora Owen, 1852: Geol. Sur. Iowa, Wisconsin and Minnesota, 



tab. v, fig. 1. 

 Productus semireticulatus Ball, 1852: Stanbury's Exp. Gt Salt Lake, p. 



411, pi. hi, figs. 4, 5. (Not Martin, 1809.) 

 Productus prattenianus Norwood <fc Pratten, 1854: Jour. Acad. Nat Sci., 



Phila. (2), vol. ll, p. 17, pi. i, figs. lOa-d. 

 Productus hildrethianus Norwood & Pratten, 1854: Jour. Acad. Nat. Sci., 



Phila. (2), vol.111, p. 18, pi. i, figs, lla-c. 

 Productus cequicostatus Shumard, 1855: Geol. Sur. Missouri, Ann. Kept., 



p. 201, pi. E, fig. 10. 



Productus cora Marcou, 1858: Geol. N. A., pi. vi, figs. 4-4a. 

 Produccus fiemingi Geinitz, 1866: Garb, und Dyas in Nebraska, p. 52, tab. 



iv, tigs. 1, 2, 3, 4. 

 Productus calhounianus Geinitz, 1866 : Garb, und Dyas in Nebraska, p. 51. 



(Not Swallow, 1858.) 

 Productus koninckianus Geinitz, 1866 : Garb, und Dyas in Nebraska, p. 53, 



tab. iv, fig. 4. (Not de Verneuil, 1845.) 

 Productus prattenianus Meek, 1872: U. S. Geol. Sur. Nebraska, p. 163, 



pi. ii, figs. 5i-c; pi. v, figs. 1-3, pi. viii, figs. lOa-b. 

 Productus prattenianus White, 1875: U. S. Geol. Sur. w. 100 Merid., vol. 



[V,p. 113, pi. vii, fi<s. 10d-c. 

 Productus cora White, 18S4 : Geol. Sur. Indiana, Ann. Rep. 1883, p. 126, 



pi. xxvi, fige. 1, 2, 3. 

 Productus cora Keyes, 1888: Proc. Acad. Nat Sci., Phila. , p. 227. 



Shell of medium size, regularly rounded anteriorly, as long 

 as wide, length of hinge-line equal to greatest breadth. Yen- 

 tral valve regularly arched, with no medial sinus ; umbonal 

 region more or less gibbous ; beak incurved ; ears rather large, 

 somewhat compressed, with a few well-marked wrinkles. Dor- 

 sal valve decidedly concave, slightly flattened posteriorly. Sur- 

 face marked by numerous fine, radiating costre, and on the 

 ventral side by a few scattered spines. 



Horizon and localities. Upper Carboniferous, Coal Meas- 

 ures : Calhoun ( Henry county ), Kansas City. 



Productus cora was originally described from South Amer- 

 ica ; while in Xorth America the same form has been given, at 



