A STUDY OF THE BRACHIOPOD GENUS PLATYSTROPHIA 



By EuLA Davis McEwan, 



Of Northwestern University, Evanslon, Illinois. 



INTRODUCTION. 



The brachiopod genus PlatystropMa ^ is of interest because of the 

 abundance of its species and the gi-eat variation exhibited in their 

 development. Eariy investigators differed considerably as to the 

 relationships of this gi-oup of brachipods and referred its species to 

 Terehratulites,^ Terehratula,^ Poramhonites,'^ AtryjM,^ Spirifer,'^ and 

 Delthyns.'' The peculiar granular surface and general outline of the 

 shell led most early writers to refer its species to Spirifer and 

 Delthyns, but the intimate structure is clearly distinct from all of 

 these genera. 



In 1848 Davidson demonstrated ^ that the internal characters of 

 this group of shells were those of Ortlds and several contemporary 

 investigators follov/ed his interpretation. In 1850 King ^ proposed 

 the name PlatystropMa for tliis group of Orthids with TerehratuUtea 

 hifomtus Schlotheim as the type. In America early investigators 

 referred these shells to Delthyris and Spirifer,^° and later to OrtMs}^ 



1 nXarur, Wide; trrpo0eti', to turn (as a hinge). 



' Schlotheim, Petrefaktenkunde auf ihr jetz. Standpunkt, 1820, p. 265. 



» Von Eichwald, Nt. Schizze von Polodien, 1S30, p. 202. 



< Pander, Beitr. zur Geognosie Russlands, 1830, p. 96. 



* Hisinger, Lethaea Suecica, 1837, p. 76. 



« Von Eichwald, SUurische Schichten-System von Estland, 1840, p. 144.— Castelnau, Essai sur le Syst. 

 Silur. de I'Am^rique septentrionale, 1843, p. 42— Phillips and Salter, Mem. Geol. Surv. United Kingdom, 

 vol. 2, 1848, p. 293.— McCoy, British Palaeoz. Fossils, 1852, p. 192. 



» De Verneuil, Gf^ol. de la Russie, vol. 2, 1845, p. 135.— McCoy, Syn. Silur. FossUs Ireland, 1846, p. 37. 



8 Davidson, Bull. Soc. G6ol. France, ser. 2., vol. 5, 1848, p. 323.— Quenstedt, Handb. der Petrefactenkunde, 

 1851, p. 486.— Davidson, Introduction British Foss. Brachiopods, pi. 8, 1853, figs. 146-148.— Salter, Murchi- 

 son's Siluria, ed. 2, 1859, p. 210.— Lindstrom, Gotland's Brachiopoder, 1860, p. 371.— Salter, Mem. Surv. 

 United lOngdom, vol. 3, 1866, pp. 259, 267, 276.— Davidson, British Silurian Brachiopoda, 1871, p. 268. 



» Mon. Permian Fossils England, p. 106. 



10 Emmons, Geol. New York, Rep. Second Dist., 1842, p. 396.— Conrad, Journ. Acad. Nat. Sci. Philadel- 

 phia, vol. 8, 1842, p. 260.— Hall, Geol. New York, Rep. Fourth Dist., 1843, p. 70.— Owen, Geol. Expl. Iowa, 

 Wisconsin, Illinois, 1844, pi. 15.— Hall, Nat. Hist. New York, Pal., vol. 1, 1847, p. 131; vol. 2, 1852, p. 192.— 

 Rogers, Geol. Petmsylvania, vol. 2, 1853, p. 820. 



u BilUngs, Canadian Nat. Geol., vol. 1, 1856, p. 206.— Hall, Twelfth Rep. New York State Cab. Nat 

 Hist., 1859, p. 66.— BilUngs, Geol. Canada, Rep. Prog., 1863, p. 167.— Nicholson and Hinde, Canadian 

 Journ., 1874, p. 158.- Meek, Geol. Surv. Ohio, Paleont., vol. 1, 1873, p. 114.— James, Cincinnati Quart. 

 Journ. Sci., vol. 1, 1874, p. 20.— White, Geogr. and Geol. Expl. west 100th Merid., 1875, p. 74.— Nicholson, 

 Rep. Pal. Prov. Ontario, 1875, p. 16.— Miller, Cincinnati Quart. Journ. Sci., vol. 2, 1875, p. 25.— James, 

 The Paleontologist, No. 1, 1878, p. 7.— White, Second .\nn. Rep. Indiana Bur. Stat, and Geol., 1880, p. 

 487; Tenth Rep. State Geol. Indiana, 1881, p. 119.— Foerste, BuU. Sci. Lab. Denison Univ., vol. 1, 1885, 

 p. 80.— Nettekoth, Kentucky Fossil Shells, 1889, p. 35. 



Proceedings U. S. National Museum. Vol. 56— No. 2297. 



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