BBACHIOPODS. 95 



Retzia verneuiliana HALL. 



Retzia verneuiliana Hall, 1856: Trans. Albany Inst , vol IV, p. 19. 

 Retzia verneuiliana Hall, 1858: Geology Iowa, vol. E, p. 657, pi. xxiii, 

 figs. V 4 - / &. - 



Like R. mormoni f but with much finer and more numerous 

 cost*. 



Horizon and localities. Lower Carboniferous, Saint Louis 

 limestone : St. Louis. 



Retzia vera HALL. 



Retzia vera Hall, 1858: Geology Iowa, vol. 1, p. 704, pK xxvii, fig. 3a. 

 Retzia vera, var. costata, Hall, 1858: Geology Iowa, vol. I, p. 704, pi. 

 xxvii, figs. 3b c. 



Shell like R. mormoni, but very much larger, and with more 

 numerous and finer radiating ribs. 



Horizon and localities Lower Carboniferous, Kaskaskia 

 limestone : Ste. Mary ( Ste. Genevieve county ). 



Retzia mormoni (MARCOU). 

 Plate xli, figs. 2a-c. 



Terebratula mormoni Marcou, 1858: Geol. N. A., p. 51, pi. vi , fig. 11. 

 Retzia punctilifera Shumard, 1858: Trans. St. Louis Acad. Sci., vol. I, 



p. 220. 

 Retzia mormoni Meek & Hay den , 1859 : Proc. Acad. Nat. Sci., Phila., 



p. 27. 



Retzia subglobosa McChesney, 1860: Desc. Pal. Foss., p. 45. 

 Retzia mormoni Geinitz, 1866: Carb. und Dyas in Nebraska, p. 39, tab. / 



iii, fig. 6. 

 Retzia punctilifera McChesney, 1867 : Trans. Chicago Acad. Sci., vol. I t / 



p. 32, pi. i, fig. 1. /y 



Retzia punctilifera Meek, 1872: U. S, Geol. Sur. Nebraska, p. 181, pi. / 



i,fig. 13 ; and pi. v, fig. 7. 

 Retzia mormoni White, 1875: U. S. Geog. Sur. w. 100 Merid., vol. IV, 



p. 141, pi. x, figs. 7a-c. 

 Retzia mormoni White, 1884: Geol. Sur. Indiana, Ann. Rep. 1883, pt. ii, / 



p. 136, pi. xxxv, figs. 10-12. 

 Retzia mormoni Keyes, 1888 : Proc. Acad. Nat. Sci., Phila., p. 231. 



Shell small, subovoid, with 12 to 16 simple, radiating 

 costte; hinge-line short, often slightly extended into small ears. 



Ventral valve the more convex; beak rather prominent, 

 rounded, somewhat curved; foramen rather large, circular; 

 cardinal area well defined, triangular. Dorsal valve moderately 



