Chap. X.] IN LOWEST FOSSILIFEROUS STRATA. 85 



" present time. We are thus carried back to a period 

 " so remote, that the appearance of the so-called 

 " Primordial fauna (of Barrande) may by some be 

 "considered as a comparatively modern event." The 

 Eozoon belongs to the most lowly organised of all 

 classes of animals, but is highly organised for its class ; 

 it existed in countless numbers, and, as Dr. Dawson has 

 remarked, certainly preyed on other minute organic 

 beings, which must have lived in great numbers. Thus 

 the words, which I wrote in 1859, about the existence 

 of living beings long before the Cambrian period, and 

 which are almost the same with those since used by Sir 

 W. Logan, have proved true. Nevertheless, the difficulty 

 of assigning any good reason for the absence of vast 

 piles of strata rich in fossils beneath the Cambrian 

 system is very great. It does not seem probable that 

 the most ancient beds have been quite worn away by 

 denudation, or that their fossils have been wholly 

 obliterated by metamorphic action, for if this had been 

 the case we should have found only small remnants of 

 the formations next succeeding them in age, and these 

 would always have existed in a partially metamorpliosed 

 condition. But the descriptions which we possess of 

 the Silurian deposits over immense territories in Eussia 

 and in North America, do not support the view, that 

 the older a formation is, the more invariably it has 

 suffered extreme denudation and metamorphism. 



The case at present must remain inexplicable ; and 

 may be truly urged as a valid argument against tlie 

 views here entertained. To show that it may hereafter 

 receive some explanation, I will give the following 

 hypothesis. From the natiu-e of the organic remains 

 which do not appear to have inliabited profound depths, 



