64 BRACHIOPODS. 



Orthis dubia HALL. 



Orthis dubia Hall, 1856: Trans. Albany Inst, vol IV, p. 12. 

 Orthis cooperensis Swallow, 1863: Trans. St. Louis Acad. Sci., vol. II, 



p. 82. 

 Orthis dubia Whitfield, 1882: Bui. American Mus. Nat. Hist., No. 3, p. 



45, pi. vi, figs. 1-5. 

 Orthis dubia Hall, 1883 : Geol. Sur. Icdiana, 12th Ann. Uept. , p. 324, pi. 



xix, figs. 1-5. 



Similar to 0. burlingtonensis but very much smaller. 

 Horizon and localities. Lower Carboniferous, Saint Louis 

 limestone : Barrett ( St. Louis county ). 



Orthis pecosii MARCOU. 



Orthis jo6coswMarcou, 1858: Geol. N. A., p. 48, pi. vi, figs. 14a-b. 

 Orthis carbonaria Swallow, 1858: Trans. St. Louis Acad. Sci., vol. I, p. 



218. 

 Orthis carbonaria Meek, 1872: U. S. Geol. Sur. Nebraka, p. 173, pi. i, 



figs. 8a-c. 

 Orthis pecosii White, 1875: U. S. Geog. Sur. w. 100 Merid., vol. IV, p. 



125, pi. ix, figs. 5a-c. 



Shell small, sub-circular in outline ; hinge-line short. Yen- 

 tral valve moderately convex, more or less distinctly flattened 

 anteriorly ; beak small, rather prominent, pointed, and arched 

 over the small well-marked area; foramen narrow. Dorsal 

 valve usually slightly more arched than the opposite valve, and 

 generally showing traces of a very shallow median sinus ; area 

 well defined, but smaller than in the other valve. Surface 

 marked by numerous fine radiating ribs, which increase by in- 

 tercalation ; these are crossed by lines of growth. 



Horizon and localities Upper Carboniferous, Coal Meas- 

 ures : Kansas City. 



Platystrophia lynx (EICHWALD). 



Plate xxxix, fig. 5. 



Terebratula lynx Eichwald, 1830 : Nat. Kizze. von Podol, p. 202. 

 Spirifer lynx Von Buch, 1837 : Ueber Delth. , p. 44, 

 Spirifer biforatus, var. lynx Hall, 1852: Pal. New York, vol. II, p. 65, pL 



xxii, figs. la-e. 

 Orthis lynx Meek, 1873 : Geol. Sur. Ohio, Pal., vol. I, p. 114, pi. x, figs. 



la-e. 



Shell attaining a large size, nearly equivale, wider than 

 long, with a transversely oval sub-quadrate outline, or, in old 



