268 BRITISH SILURIAN BRACHIOPODA. 



Length 20, width 25, depth 6 lines. 



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Obs. This is one of the largest of our British Silurian species of Orthis, and is easily 

 distini;uishable from its congeners by the remarkable flatness of its dorsal valve, as well 

 as by the shape of its brachial appendages. It received the manuscript name of patera 

 from the late Mr. Salter, which designation is here retained. 



Position and Locality. It occurs under the conditions of external and internal casts and 

 impressions in the Tipper Caradoc at Corston Farm, Hopesay, from which locality a 

 fine series of specimens may be seen in the Museum of Practical Geology. 



Orthis BiFOUATA, ScMofh, (sp.). PL XXXVIII, figs. 11—25. 



Terebratulites Bifo^k-tv?,, Schlofheim. Petrefact.* p. 265, 1820. 

 Terebratula Lynx, iJ'Eichwald. Nat. Skizze von Podol., p. 202, 1830. 

 PoRAMBONiTES DENTATUS and P. BREVis, Pander. Beitr. Geogn. Rnssl., p, 96, 



pi. ii, figs. 4, 5, 1830. 

 Atrypa dorsata? Hisinger. L'eth. Suec, p. 76, pi. xxi, fig. 14, 1837. 

 Spirifer Lynx, Von Buck. Ueber Delth., p. 44, 1837; and Mem. Soc. Geol. France, 

 vol. iv, p. 190, 1840. 



— BTFORATUS, UEichw. Sil. Syst. in Estlil., p. 144, 1840. 



Delthyets brachynota, J. Hall. Rep. 4th Geol. District N. York, p. 71, fig. 6, 1843. 

 Spirifer Sheppardi, Be Castelnau. Ter. Sil. de I'Amerique du Nord, p. 42, pi. xiv, 

 fig. 15, 1843. 



— BIFORATUS, and varieties Lynx et dentatus. Be Verneiiil e\. BeKeyserl. Geol. 



Russia, vol. ii, p. 135, pl. iii, figs. 3 — 5, 1845. 



— tridens, Sp. Lynx, and Sp. terebratuliformis, M'Coy. Syn. Sil. Foss. 



IreL, pp. 37, 38, pL iii, figs. 25—27, 1846. 

 Delthyris BIFORATUS, var. Lynx, J. Hall. Pal. N. York, vol. i, p. 133, pl. xxxii d, fig. 



i, 1847 ; and vcl. ii, p. 65, pl. xxii, fig. 1, 1851. 

 Okthis biforata, Bav. Bull. Soc. Geol. France, 2nd ser., vol. v, p. 323, pl. iii, fig. 25, 

 1848. 



— — (= Spirifer subsulcatus. His.), Be Fern. Bull. Soc. Geol. France, 



2nd ser., vol. v, p. 347, 1848. 

 Spirifera — Phillips and Salter. Mem. Geol. Survey, vol. ii, p. 293, 1848. 



Platystrophia bifokata, King. Monogr. Permian Fossils, p. 106, 1849. 

 Orthis Lynx, Quenstedt. Handb. der Petref., p. 486, pl. xxxix, figs. 8 — II, 1851. 

 Spirifera biforata, var. Lynx and var. fissicostata, M'^Coy. Brit. Pal. Foss., pp. 



192 & 193, 1852. 

 Orthis — Bav. General Introduction, pl. viii, figs. 146, 148, 1853. 



— — Salter. Siluria, 2nd ed., p. 210, pl. xxxiii, fig. 4, 1859. 



— Lynx, Schmidt. Sil. Form. Liv.- Ehst, &c., Archiv, vol. ii, p. 215, 1858. 



— biforata, Lindstrdm. Gotland's Brachiopoder, p. 371, 1860. 



— — Salter. Mem. Geol. Survey, vol. iii, pp. 259, 267, 276, 1866. 



