88 ORGANIC EVOLUTION CONSIDERED 



When it is remembered that the Potsdam, or 

 Primordial, is the first period in which undoubted 

 fossil remains are found, it will be seen that the time 

 which elapsed from the appearance of Eozoon to that 

 of the fossils in the Potsdam is nearly equal to the 

 time from the Potsdam to the present. 



Dana gives the time ratios for the Paleozoic, 

 Mesozoic andCenozoic as 12: 3: 1. 



According to Logan's estimate, which Lyell seems 

 to accept, the length of time between Eozoon and 

 Potsdam was equal to the Paleozoic and Mesozoic 

 combined, which, according to Dana, include fifteen 

 of the sixteen parts of time between the beginning of 

 the Potsdam and the present. 



Here, then, we find an enormous stretch of time 

 which may perhaps amount to 50,000,000 years be- 

 tween the dawn of the Eozoon and the Potsdam, in 

 which no fossil has been found. 



If Eozoon was a protozoan, as is claimed by some, 

 and if the various fossils that are found in the 

 Potsdam were evolved, from Eozoon and other 

 Archaean forms, then it seems strange beyond belief 

 that not one of the vast number of intermediate 

 forms that must have existed has been found. 



We are told that the Eozoon had a calcareous skel- 

 eton, which is the kind of material most common in 

 the hard parts of marine forms. 



It may, of course, be claimed that the fossils of the 

 Archaean have all been obliterated except Eozoon. 

 Le Conte says: " It is impossible to say that animals 

 of low form did not exist; yet the absence of any 

 reliable trace in rocks not more metamorphic than 

 some of the next era, which are crowded with fossils 

 of many kinds, seems to indicate a paucity, if not an 

 entire absence, at this time, of such animals."* 



* Elements of Geology, p 287. 



