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, 0. striata, O. undulata, 0. amulata, 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 1834 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. (Lethcea Geognostica.) 
In 1837, Mr. Stokes described Actinoceras Lyonii, A. Bigsbii, and A. Richardsoni, 
28 
