244 QUARTERLY JOURNAL. 



in the coal beds, existed in a free state in the atmosphere during 

 the whole period antecedent to their formation; and hence, the at- 

 mosphere was rendered irrespirable by land animals. The main 

 fact, and probably the only one, which favors this doctrine is, the 

 the supposed non-discovery of the remains of these animals ih 

 rocks of the coal series, or those which are nearly cotemporaneous 

 with them. It will be admitted, no doubt, on all hands, that it is 

 dangerous, in all cases, to found a position on a negative ; espe- 

 cially, in the observational sciences, for we know not how soon 

 some fortunate discovery, or it may, perhaps, be called unfortunate 

 in one sense, will entirely upset the best constructed theory ; cer- 

 tainly such is the case in regard to this part of the author's as- 

 sumption. If the supposed absence of land animals in the rocks i 

 just referred to, is sufficient in itself to give weight to the view, that ' 

 the atmosphere was irrespirable previous to the period of the coalli 

 deposits, certainly the discovery of facts proving their existence, 

 ought at least, to nullify the assertion, or take away all weight 

 and value to an argument formed upon such a premise. But, be 

 that as it may, the existence of land animals is as clearly proved 

 in the coal era as in that of the new red sandstone. "We allude 

 now to the discovery of foot-marks of birds and quadrupeds deep 

 in the rocks of the carboniferous series, in Pennsylvania, by Dr. 

 King. The observations seem to have been made with proper 

 care, and to be as much entitled to our belief as those which have 

 been made in the system of rocks above them, viz : the new red 

 sandstone of the valley of Connecticut river. From this repre- 

 sentation, then, we do not perceive that there is sufficient ground 

 for what the author asserts in regard to the condition of the at- 

 mosphere, in the period referred toj and hence, so far as such a 

 view may be considered as bearing favorably on the hypothesis of 

 organic progress, as developed in the vestiges of creation, we can- 

 not for oursehes, see that it has much if any Weight. We dwell 

 no longer upon the points specified above, inasmuch as it is suf- 

 ficient for our purpose, to show that in this country carbon appear- 

 ed as a constituent of the rocks, long anterior to organic beings ; 

 and that so far as the condition of the atmosphere is concerned, 

 we have no occasion for basing an hypothesis on a negative posi- 

 tion, in as much as we have that proof which warrants almost the 

 assertion that the atmosphere was as respirable in the period of 



