192 PALEONTOLOGY OF NEW YORK. 



Trenton, and 0. Davidsoni, de Verneuil (0. calli gramma, 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. caUigramma, 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, O. basalts and 0. elegantula be- 

 long to a distinct type of structure.! 



ORTHIS, Dalman, as restricted. 

 I. Group of Orthis callactis, Dalman. 1828. 



TLATE V, FIGS. 1-17, 37-41. 



1828. OrtUs, Dalman. Kongl. Vet. Acad. Hiindl., pp. 93, 90. 



1830. Orthamboii.lt.es. Pander. iSeitr. zur geogncis. des i-ussisch. Reiches, p. 80, pi. iii, fig. 7 ; pi. xxviii, 



fig. 18. 



1839. Orthis, SowKRBY. Murchison's Silurian Syst., p. 639, pi. xxi, tig-. 8. 



1843. Orthis, Hall. Geology N. Y. ; Rept. Second Dist., p. 105, fig. 3. 



1843. Orthis, Conrad. Pi'oc. Acad. Nat. Sci., Philadelphia, vol. i, p. 333. 



1844. Orthis, Owen. Geol. Expl, Iowa, Wisconsin and Illinois, pi. xv, fig. 11. 



1847. Orthis, Hall. Pala;ontology N. Y., vol. I, p. 20, pi. iv his, fig. 4 ; pp. 119, 121, pi. 32. 



18r)2. Orlhin. Hall. Palseontology 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. PaU-eozoic Fossils, vol. 1, 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. 11)7. fig. 151 ; p. 231. fig. 245; p. 312, 



fig. 318. 

 1865. OrtMs, Siialer. Bnllclin No. 4, Mns. Comparative Zool., p. 66. 

 1875. OrthU, Nichol.son. Palaeontology Province Ontai-io, p. 47, fig. 21. 

 1875. OrttiU, White. Geogr. and Geol. Expl. west 100th Merid., p. 72, pi. iv., tig. 10. 

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

 figs. 1-8. 



* Bi-iti.sh 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, rei)rodii<:ed by jihoto-engraving the fii-st 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- 

 ceiling the lithographic plates. These plates are Tab. I and II of the Kong. Vetenskaps-Academiens 

 Handlingar for ar 1827, and bear all of the authoi-'s figures of the species of Oktiiis as well a.s those of his 



genus LEPTiBNA. 



