188 Observation on Trilobites 



fore, probably correct in classing this formation as transition, 

 although he enumerates fossils that never occur in rocks of 

 that class, and among others, the Belemnite and Gryphite, 

 In all our specimens we do not find any of these species; we 

 must therefore conceive that he has. been under some error 

 in this statement, having probably mistaken a small kind of 

 Orihocera for the former, and the Nautilus for the latter of 

 these petrifactions. 



American Localities of Trilobites. 



It is an interesting subject of inquiry, how far the fossil 

 species of our continent agree with, or differ from those of 

 Europe. It is a fact well known, that the living animals 

 which inhabited America at the time of its discovery, were 

 entirely different from those of the old world. Analogy 

 would lead us to infer, that a similar law might hold good in 

 relation to extinct species and genera. This, however, 

 does not appear to be the case, for, in comparing the 

 American rocks that have hitherto been examined, and their 

 fossil contents, w'u;h those of Europe, it would seem to be 

 probable, that the remains they contain are identical, there 

 being no variation of any great importance in the contents of 

 similar rocks. A few instances do indeed occur of extinct 

 animals found in one continent, and not in the other, but 

 they are not sufficiently numerous to constitute more than an 

 exception to this general rule, and they are always accom- 

 panied by species that are common in both hemispheres. 



Trilobites have been found in many different localities of 

 North America, and the industry of several indefatigable 

 collectors is hourly adding to the number. 



The Calymene of Blumenbach occurs at Trenton Falls, at 

 Black Rock on the Niagara, and on the Miami river; the 

 Calymene macropthalma, on the Helderberg Mountain near 

 Albany, and at Coshung Creek near the Seneca Lake, in the 



