192 
PALAEONTOLOGY OF NEW YORK. 
Trenton, and 0. Davidsoni, de Verneuil (0. calligramma, var., according to 
Davidson*), of the Niagara. 
Mr. Davidson was disposed to regard the Swedish specimens of 0. callactis as 
showing but varietal differences from 0. calligramma , and his use of these two 
terms, the former subordinate to the latter, should strictly be reversed. Orthis 
callactis may, therefore, properly be taken as the typical form of the genus in 
its restricted construction, and upon the diagnosis above given it will be neces¬ 
sary to exclude the remainder of Dalman’s species, with the exception of 0. 
demissa, as it will be shown that 0. testudinaria, 0. basalis and 0. elegantula be¬ 
long to a distinct type of structure.! 
ORTHIS, Dalman, as restricted. 
I. Group of Orthis callactis, Dalman. 1828. 
PLATE V, FIGS. 1-17, 37-41. 
1828. Orthis, Dalman. Kongl. Vet. Acad. Handl., pp. 93, 96. 
1830. Orthambonites, Pandek. Beit.r. zur geognos. des russiseh. Reiches, p. 80, pi. iii, fig. 7; pi. xxviii, 
fig. 18. 
1839. Orthis, Sowerby. Murchison’s Silurian Syst., p. 639, pi. xxi, fig. 8. 
1843. Orthis, Hall. Geology N. Y.; Rept. Second Dist., p. 105, fig. 5. 
1843. Orthis, Conrad. Proc. Acad. Nat. Sci., Philadelphia, vol. i, p. 333. 
1844. Orthis, Owen. Geol. Expl. Iowa,Wisconsin and Illinois, pi. xv, fig. 11. 
1847. Orthis, Hall. Palaeontology N. Y., vol. i, p. 20, pi. iv bis, fig. 4; pp. 119, 121, pi. 32. 
1852. Orthis, Hall. Palaeontology of N. Y., vol. ii, pp. 254, 255, pi. Iii, figs. 6, 7. 
1856. Orthis, Billings. Canadian Nat. and Geol., vol. i, p. 136, pi. ii, fig. 6. 
1859. Orthis, Billings. Canadian Nat. and Geol., vol. iv, p. 440, fig. 20. 
1859. Orthis, Salter. Canadian Organic Remains, Decade i, p. 39, pi. ix, figs. 1-4. 
1862. Orthis, Billings. Palaeozoic Fossils, vol. i, p. 77, fig. 70; p. 78, fig. 71; p. 81, fig. 73. 
1862. Orthis, Hall. Geology of Wisconsin, vol. i, p. 42, figs. 8-11; p. 435. 
1863. Orthis, Billings. Geology of Canada, p. 130, fig. 60; p. 167, fig. 151; p. 231, fig. 245; p. 312, 
fig. 318. 
1865. Orthis, Shaler. Bulletin No. 4, Mus. Comparative Zool., p. 66. 
1875. Orthis, Nicholson. Palaeontology Province Ontario, p. 47, fig. 21. 
1875. Orthis, White. Geogr. and Geol. Expl. west 100th Merid., p. 72, pi. iv., fig. 10. 
1883. Orthis, Hall. Rept. N. Y. State Geologist for 1S82, pi. xxxiv, figs. 35-38, 41, 42 and pi. xxxv, 
figs. 1-8. 
* British Silurian Brachiopoda, p. 244. 
t Dalman’s paper of 1828 has become so rare as to be beyond the reach of most American students. 
We have, therefore, reproduced by photo-engraving the first two plates of this work with the precise form 
and arrangement of the original, and they will be found inserted at the end of these discussions, and pre¬ 
ceding the lithographic plates. These plates are Tab. I and II of the Kong. Vetenskaps-Academiens 
Handlingar for ar 1827, and bear all of the author’s figures of the species of Orthis as well as those of his 
genus Lept^na. 
