192 PALEONTOLOGY OF NEW YORK. 



Trenton, and O. Davidsoni, de Vernenil (O. calligrammn, 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 he reversed. Orthis 

 callactis may, therefore, properly be taken as the typical form of the genus in 

 its restricted construction, ami upon the diagnosis above given it will be neces- 

 sary to exclude the remainder of Dalman's species, with the exception of O. 

 demissa, as it will be shown that 0. lestudinaria, 0. basalts and 0. elegantula be- 

 long to a distinct type of structure.! 



ORTHIS, Dalman, as restricted. 

 T. Group of Orthis callactis, Dalman. 1828. 



I'LATE V, FIGS. 1-17, 37-41. 



1S28. Ortliis, Dalman. Kongl. Vet. Acad. Handl., pp. 93, 96. 



1830. Orthambonltes. Pandek. Beitr. zur geogiios. des russisch. Rciche.s, p. 80, pi. iii, tig-. 7 ; pi. xxviii, 



fiff. 18. 



1839. Orflds, Sowerby. Mui-chison's Silurian Syst., p. 639, pi. xxi, lig-. 8. 



1843. Orthis, Hall. Geology N. Y. ; Rept. Second Dist., p. 105, tig. n. 



1843. Ortlds, CoxNhad. Proc. Acad. Nat. Sci., Philadelphia, vol. i, p. 333. 



1844. OrlhU, Owen. Geol. Expl. Iowa, Wisconsin and Illinois, pi. xv, tig. 11. 



1847. Orthis, Hall. Palaeontology N. Y., vol. i, p. 20, pi. iv bl% fig. 4 ; pp. 119, 121, pi. 32. 



18'>2. Orthli. Hall. Palaeontology of N. Y., vol. ii, pp. 254, 255, pi. Hi, tigs. 6, 7. 



1856. Orthis, Billing.s. Cana<lian Nat. and Geol., vol. i, p. 136, pi. ii, fig. 6. 



1859. Orth'is, Billings. Canadian Nat. and Geol., vol. iv, p. 440, tig. 20. 



1859. Orthis, Salter. Canadian Organic Remains, Decade i, p. 39, pi. ix, tigs. 1-4. 



1862. Orthis, Billings. PaljEozoic Fo.ssils, vol. i, p. 77, tig. 70 ; p. 78, fig. 71; p. 81, tig. 73. 



1862. Orthis, Hall. Geology of Wisconsin, vol. i, p. 42, tigs. 8-11 ; p. 435. 



1863. Orthis, Billings. Geology of Canada, p. 130, fig. 60; p. 167, tig. 151 ; p. 231, tig. 245; p. 312, 



fig. 318. 

 1865. Orthis, Shaler. Bnlletin No. 4, Mus. Comparative Zool., p. 66. 

 1875. Orthis, Nicholson. Palaeontology Province Ontario, p. 47, fig. 21. 

 1875. Orthis, White. Geogr. and Geol. Expl. westlOOlh Merid., p. 72, pi. iv., fig. 10. 

 1883. Orthis, Hall Rept. N. Y. State Geologist for 1882, pi. xxxiv, figs. 35-38, 41, 42 .ind pi. xxxv, 

 figs. 1-8. 



* Bi-itish Sihirian BraRhio|ioda, p. 244. 



t Dalman's paper of 1828 lias become so rare as to be beyond the leach of most American stuilents. 

 We have, thei-efore, reprodm-ed by [ihoto-engraving the first two plates of this work with the pi-ecise 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 

 genua LEPT.aENA. 



