Chap. X.] IN LOWEST POSSILIFBROUS STBATA. gg 



"zoic series to the 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 diffi- 

 culty 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 ob- 

 literated by metamorphic action, for if this had heen 

 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 metamorphosed 

 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 the 

 views here entertained. To show that it may hereafter 

 receive some explanation, I will give the following hy- 

 pothesis. From the nature of the organic remains 

 which do not appear to have inhabited profound depths, 



