BRACHIOPODA. 201 



184S. Orthis, Davidson. Bull. Soc. Geol. France, 2d ser., vol. v, p. 323. 



1848. S'pirifem, Phillips and Saltek. Mem. Geol. Survey Uniled King-dom, vol. il, p. 293. 



1850. Platystroplda, King. Monogr. Permian Fossils England, p. 106. 



1S51. Orthis, Quenstedt. Handb. der Petrefactenkunde, p. 486. 



1852. Spirifer, Hall. Palfeontology of N. Y., vol. ii, p. 65. 



1852. Spirifer, McCoy. British Palsoz. Fossils, p. 192. 



1853. Orthis, Davidson. Introd. British Foss. Brachiopoda, plate viii, figs. 146-148. 

 1856; Orthis, Billings. Canadian Natui-alist and Geologist, vol. i, p. 206. 



1858. Delthyris, Roguks Geology of Pennsylvania, vol. ii, p. 820. 



1859. Orthis, Salter. Murchison's Siluria, 2d ed., p. 210. 



1859. Orthis, Hall. Twelfth Rept. N. Y. State Cab. Nat. Hist., p. 66. 



1860. Orthis, Lindstrom. Gotland's Brachiopoder, p. 371. 



1863. Orthis, Billings. Geology of Canada, Report of Progress, p. 167. 



1865. Platystrophia, Shaler. Bull. Museum Comparative Zool., No. 4, p. 67. 



1866. Orthis, Salter. Mem. Geol. Survey United Kingdom, vol. iii, pp. 259, 267, 276. 

 1871. Orthis, Davidson. Bi-itish Silurian Brachiopoda, p. 268. 



1873. Orthis {Platystrophia], Meek. Geol. Survey Ohio; Palaeontology, vol. i, p. 114. 



1874. Orthis (Platystrophia), James. Cincinnati Quart. Journ. Sci., vol. i, p. 20. 



1874. Orthis, Nicholson and Hinde. Canadian Joui-nal, p. 158. 



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

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

 1875. Orthis, Nicholson. Rept. Palaeontology Pi-ov. Ontario, p. 16. 

 1878. Orthis (Platystrophia), James. The PaL-eontologist, No. 1, p. 7. 



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



1881. Orthis, White. Tenth Report State Geologist Indiana, p. 119. 



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



1SS3. [Platystrophia]. Hall. Rept. N. Y. State Geologist for 1SS2, pi. 34. 



1885. Orthis, Foerste. Bull. Denison University, vol. i, ii. 80. 



1887. Platystrophia, Shaler. Mem. Kentucky Geol. Surv., vol. i, pt. 3, pp. 43, 44. 



1889. Orthis, Nettelroth. Kentucky Fossil Shells, p. 35. 



1889. Platystrophia, Hall. Bull. Geol Society Amei-ica, vol. 1, p. 19. 



The name Platystrophia proposed by Dr. King, has 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 nearly 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 the 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 Buck, 1840, Ueber Delthyris; von Eichwald, 1840, Silur. Schichten-system in Esthland ; Emmons, 

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

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

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



