IMPERFECTION OF GEOLOGICAL RECORD 91 



tem in Canada, in the lowest of which the Eozoon is 

 found. Sir W. Logan states that their "united thickness 

 may possibly far surpass that of all the succeeding rocks, 

 from the base of the paleozoic 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 Bar- 

 rande) may by some be considered as a comparatively 

 modern event." The Eozoon belongs to the most lowly 

 organized of all classes of animals, but is highly organ- 

 ized 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 ab- 

 sence of vast piles of strata rich in fossils beneath the 

 Cambrian system is very great. It does not seem prob- 

 able 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 met- 

 amorphosed condition. But the descriptions which we 

 possess of the Silurian deposits over immense territories 

 in Russia and in Korth 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 



