*** We have, foi' the present, confined our enumeration of Specimens 
to such as arise from differences of form. The constituent substances of the 
petrifaction, though necessary to be noticed in a geological point of view, 
are not essential to the discrimination of the species or its varieties. (Vide 
Introduction. Art. Specimen. Figure. Constituent Substance, &cc.) 
It will be evident to the reader, that the anglicised names of the 
petrifactions given in the following arrangement, are not those in general 
use — Indeed, from the little attention hitherto paid the subject by common 
observers, scarcely any appellations, appropriate to the species, at present 
exist in our language — Those w'e have ventured on, are, with deference, 
offered for adoption, as the most expressive that occur to us. 
