BRACHIOPODA. 163 



imbricating concentric lines. The structure of the cardinal process differs in 

 some respects from that of Atrypa reticularis, being much more like that of 

 Zygospira modesta ; while, in regard to the brachial apparatus, the coiling of 

 the spirals is lax, the cones themselves introverted more as in Zygospira 

 than in Atrypa, and the loop, though posterior in position, is apparently con- 

 tinuous and acutely angled as in Catazy'ga. 



To this group may be applied the foregoing term, Atrypina, a name suggest- 

 ing the affinities of the fossils. 



Genus ATRYPA, Dalman. 1828. 



PLATE LIV. 



1767. Anmnia, Linne. Systema Naturae, ed. xii, p. 1152. 



1820 TerebratuUtes, Sohlotheim. Petrefactenkuntle, p. 2G2, Naohti-., pi. xvii, tig. 2 ; pi. xviii, fig-. 2 ; 

 pi. XX, fig. 4. 



1821. Anomites, Wahlenberg. Nov. Act. Reg-. Soc. Scientif. Upsal., vol. viii, p. 65. 



1822. Terebrattda, Sowkrby. Mineral Coiicholog-y, vol. iv, p. 324, fig-. 2. 



1828. Atrypa, Terebratiila, Dalman. Kongl. Vetenskaps. Akad. Handliugar, pp. 127, 128, 143, pi. iv, 



figs. 2, 3 ; pi. vi, fig. 6. 

 1837. Atrypa, Terebratula, Hisingeb. Lethsa Suecica, pp. 75, 81, pi. xxi, figs. lla-e;pl. xxiii, 



figs. 8 a~c. 

 1842. Atrypa, Conrad. Jour. Acad. Nat. Sci. Philadelphia, vol. viii, p. 265. 



1842. Atrypa, Hipparionyx, Vanuxem. Geology of N. Y.; Rept. Third Dist., p. 88, fig. 12; p. 132, 



fig. 2 ; p. 139, fig. 5; p. 163, fig. 3; pp. 164, 182, fig. 4. 



1843. Teribratula, Castelnau. Essai sur le Systeme Silurien, p. 40, pi. xiii, fig. 8. 



1S43. Atrypa, Hall. Geology of N. Y'.; Rept. Foui-th Dist., p. 73, fig. 8 ; p. 108, fig. 37 ; p. 175, fig. 5; 

 p. 198, tig. 4; p. 200, figs. 1, 2; p. 215, fig. 3; p. 271, figs. 1-3; Tab. of Org. 

 Rem., No. 13, fig. 1. 



1844. Atrypa, Q-wen. Geol. Expl. of Iowa, 'Wisconsin and Illinois, pi. xii, figs. 2, 10. 

 1847. Spirigerina, d'Orbigny. Comptes rendus, vol. xxv, p. 268. 



1847. Terebratula, Y'andell and Shdmard. Contribution to the Geol. of Kentucky, p. 10. 



1849. Terebratula, Hall. American Journ.al of Science, vol. xx, p. 227. 



1852. Atrypa, Hall. Palaeontology of N. Y., vol. ii, pp. 72, 79, 270-272, pi. xx, fig. 10 ; pi. xxiii, fig. 8; 



pi. Iv, fig. 5 ; pi. Ivi, figs. 1, 2. 

 1852. Rhynckonena, Salter. Sutherland's Jour, of a Voyage in BaSin's Bay, etc., vol. ii, p. 221, pi. v, 



figs. 1-3, 5. 

 1S54. Atrypa, Davidson. Introd. British Fossil Brachiopoda, p. 90, pi. vii, figs. 87-94. 



1856. Atrypa, Billings. Canadian Nat. Geol., vol. i, pp. 134, 137, 474, pi. ii, fig. 10 ; pi. vii, fig. 11. 



1857. Atrypa, Hall. Tenth Rept. N. Y. State Cab. Nat. Hist., p. 122, figs. 1-7 ; p. 168. 



1S58. AtryjM, Rogers. Geology of Pennsylvania, vol. ii, part ii, p. 828, fig. 671 ; p. 829, fig. 681. 



1858. Atrypa, Hall. Geol. of Iowa, vol. i, part ii, p. 515, pi. vi, fig. 3. 



1859. Atrypa, Hall. Paleontology of N. Y., vol. iii, p. 253. pi. xlii, fig. 1. 



1860. Atrypa, Hall. Thirteenth Rept. N. Y. State Cab. Nat. Hist., p. 84. 



1860. Atrypa, Roemer. Die Silurische Fauna der westlichen Tennessee, p. 69, pi. v, figs. 9, 10. 



1860. Trematospira, McChesney. New Pal.-eozoic Fossils, p. 71. 



1861. Atrypa, Billings. Canadian Journal, vol. vi, p. 264, figs. 84-87. 



