CEPHALOPODA. 



ORTHOCERAS, Breynius. 

 HISTORICAL SKETCH. 



The earliest notice of fossils of this genus, or of generically related forms, 

 from America, so far as known to the writer, was published in England by 

 Charles Stokes, Esq. 



In 1823 Mr. Stokes published a description of the genus Huronia, and 

 described the species H. Bigsbyi, H. vertebralis, H. turbinata, H. obliqua, and 

 H. sphceroidalis, from the limestones of Drummond Island in Lake Huron 

 (Notes on the Geography and Geology of Lake Huron, by John J. Bigsby, M. D. — 

 Trans. Geol. Soc. London, 2d series, vol. 1). 



In 1832 Prof. Amos Eaton published descriptions and figures illustrating 

 " Orthocera circularis, O. striata, O. undulata, 0. annulata, 0. conica, and 0. para- 

 doxical The first four named species were obtained at Thessalon Island in 

 Lake Huron. All these, with the exception of 0. conica, appear to have been 

 identified, by Eaton, with species described under the same names in Sowerby's 

 Mineral Conchology. It is evident from the figure of O. paradoxica, given by 

 that author, that the fossil is a portion of a species of Gyroceras, from the 

 Upper Helderberg limestone. 



In 1831 Prof. H. G. Bronn established the genus Actinoceras, founded upon 

 the illustrations of the Orthoceratites of Thessalon Island, Lake Huron, pub- 

 lished in the Transactions of the Geological Society of London. {Lethtza Geognostica.) 



In 1837, Mr. Stokes described Actinoceras Lyonii, A. Bigsbii, and A. Richardsoni, 

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