BRACHIOPODA. 201 



184S. OrtUs, Davidsox. Bull. Soc. Geol. Krance, 2il ser., vol. v, p. 323. 



1848. Spirifem, Phili.ii'S .\xd S.ii.ter. Mam. Geol. Survey Unilert Kiiiffdom, vul. ii, \,. 293. 



1850. Platystroplna, Kixa. Moiiogr. Permian Fossils Eng'land, p. lOt). 



1851. Orthis, Qdensteut. IIuiull). der Petiefactenkuinle, p. 4St!. 



1852. Spirifei; H.\i,i,. PiiUx'ontolog^y of N. Y., vol. ii, p. 65. 



1853. Spinfei; McCoy. British Palivoz. Fossil.s, p. 192. 



1853. Ort?iis. DAvinso.v. Intioii. Brilisli Fo.ss. Bnichiopoda, plate viii, tir^s. 14fi-148. 



1856. OHIiis, Billings. Canadian Naturalist and Geologist, vol. i, p. 206. 



1858. DeWiyris, Roohhs Geology of Pennsylvania, vol. ii, p. 820. 



1859. Orthis, S.\LTER. Miirclii.<(ni's Silui-ia, 2d ed., p. 210. 



1850. Orthis, Hall. Twelfth Rei)t. N. Y. State Cab. Nat. Hist., p. 66. 



18GI). OrthU, Li.ND.STRo.M. Gotland's Bracliiopoder, p. 371. 



1863. 0)-i*2S, Billings. Geology of Canada, Report of Progress, p. 167. 



1865. Plati/strophia, Shaleh. Bull. Museum Comparative Zool., No. 4, ]>. 67. 



1866. Orllilt, Salter. Mem. Geol. Survey United Kingiloin, vol. iii, pp. 259, 267, 276. 

 1871. Orthis. David.son. Britisli Silurian Brachiopoila, p. 268. 



1873. Orthis (Platystrnphla), Meek. Geol. Survey Ohio; Palaeontology, vol. i. p. 114. 



1874. Ortliis {Platystrophia), James. Cincinnati Quart. Journ. Sci., vol. i. p. 20. 



1874. (.H-tliis. Nicholson and Hinde. Canadian' Journal, p. 158. 



1875. Orthis. White. Geogr. and Geol. Expl. west 100th Meriil., p. 74. 

 1875. Orthis, Miller. (Cincinnati Quar. Journ. Sci., vol. ii, p. 25. 

 1875. Orthis, Nicholson. R(>pt. Pala'Ontology Prov. Ontario, p. 16. 

 1878. Orthis (Platystrophia), James. The PaUeontologist, No. 1, p. 7. 



1880. Orthis. Whlte. Second Ann. Rept. State Bureau Stat, and Geol., Indiana, p. 487. 



ISSl. Orthis. White. Tenth Report Slate Geologist Indiana, p. 119. 



1883. Platystropliia, Hall. Thirty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 34. 



1SS3. IPlatystrojihial. Hall. Rept. N. Y. State Geologist for 18S2, y.l. 34. 



1885. 0)ihis, Foerste. Bull. Denison University, vol. i, p. 80. 



1S87. Platystrophia, Siialer. Mem. Kentucky Geol. Surv., vol. i, pt. 8, pp. 43. 44. 



1889. Orthis, Nettelrotii. Kentucky Fossil Shells, ii. 35. 



1889. Platystrophia, Hall. Bull. Geol Society America, vol. 1, p. 19. 



The name Platystrophia proposed by Dr. King, ha.s come into very general 

 use for a group of orthids having a strikingly spiriferoid exterior. The hinge- 

 line and area are long and straight and near!}' equally developed on the two 

 valves. Both valves are very convex, the brachial being the more so and 

 bearing a very strong median fold corresponding to a deep sinus on tlie oppo- 

 site valve. The valves are marked by strong, sharp plications, which 

 extend over the fold and sinus, and the external surface is finely granulose, 

 the latter feature being rarely well retained. This peculiar exterior, so unlike 

 anything met with elsewhere in the genus Orthis, readily deceived earlier 

 writers into referring the species to Delthyris or Spirifer,* and Mr. Davidson 



*VoN Bucu, 1840, Ueber Delthyris; voN Eicuwald, 1840, Silur. Schichten-systera in Esthland ; Emmons, 

 1842,Geol. of N. Y. : Rept. Second Dist. ; Conr.ad, 1842, Jour. Acad. Nat. Sci. Phila. ; Hall, 1843, Geol. of N. 

 Y.; Rept. Fourth District; de Vernedil, Geol. de la Russie; McCoy, Synopsis Silur. Foss. Ireland; Phillips 

 and Salter. Mem. Geol. Surv. United Kingdom ; Hall. 1847, 1852, Pala;ontology of N. Y., vols, i and ii. 



