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Art. III .— On Petrifactions, or Fossil Organic Remains. By 
Baron Alexander Humboldt. 
Of the various proofs of the identity of formations in the most 
distant regions of the globe, one of the most striking, and for 
which we are indebted to the assistance of zoology, is the iden- 
tity of the organic bodies contained in strata having a similar 
geological position. The researches which lead to this kind of 
proofs, have exercised the skill of the learned, since Messrs 
De Lamarck and Defrance began to determine the fossil 
shells of the neighbourhood of Paris, and since Messrs Cuvier 
and Brongniart published their memorable works on the fossil 
bones and tertiary formations. As the greater portion of the 
formations which compose the crust of our planet contain no 
organic remains, and as these remains are of very rare occur- 
rence in the transition formations, and are often broken and 
difficult to detach from the rock in the older secondary forma- 
tions, the study of fossil organic bodies comprehends but a small 
part of geognosy, — a part, however, very worthy of the attention 
of the philosopher. The problems which present themselves in 
this department, are numerous: They bear relation to the geogra- 
phy of animals, whose races are extinct, and which, for this rea- 
son, already belong to the history of our planet : They render 
necessary the discussion of the zoological characters, by which we 
would distinguish the different formations. To remain faithful 
to the plan which I have proposed to myself, of only consider- 
ing the various objects in the most general way, I shall now 
mention those questions of Geognostical Zoology, which appear 
the most important in the present state of science, and whose 
solution has been tried with more or less success. What are the 
Genera, and (if the state of preservation and degree of attach- 
ment to the rock permit a more complete determination) what 
are the Species, to which the fossil remains may be referred ? 
Does an exact determination of the species discover any which 
are identical with the plants and animals of the present world ? 
What are the classes, the orders, and families of organized be- 
ings, which present the greatest number of these analogies ? In 
what proportion does the number of identical genera and species 
increase, with the newness of rocks or of earthy deposits P Is the 
