196 GEOLOGICAL DISTEIBUTIOK. 



grounds for relegating that giiasi-OTgauisTn to the class of mineral 

 deposits.* 



Darwin has sought to explain the anomaly on the supposition 

 that possibly the most ancient fossiliferous deposits lie buried deep 

 beneath the floor of our existing oceans, and that they may have 

 lain there ever since the Cambrian (Silurian) period. They would 

 then have been kept out of sight, and would, at the same time, 

 have offered no opportunities for their remains to become inter- 

 mingled with those of any subsequent formations. That there is 

 no insuperable objection to this explanation every one must admit, 

 and that it, at least, partially meets the case, is more than prob- 

 able. But it is still far from being in the nature of a demonstra- 

 tion. The doctrine of the permanency of land areas and oceanic 

 basins has much in its favour, and if true, would go far towards 

 supporting Darwin's proposition; but, unfortunately, the absolute 

 proofs of such a condition are still wanting, and may forever re- 

 main wanting. The land surfaces from which the Paleozoic rocks 

 derived their sediments, either in part or in whole, may or may not 

 have occupied the position of the present seas. If the former be the 

 case, the problem remains in its original form; if the latter, it must 

 be assumed that a broad hiatus exists between the Laurentian and 

 Cambrian series, and that the gap is filled by vast submarine de- 

 posits, upon which massive accumulal ions of continental and organic 

 debris have been superimposed. Fossils of a pre-Cambrian type may 

 be abundant in these deposits. Manifestly, however, the assump- 

 tion of large land areas depressed beneath the sea carries with it the 

 implication of an alternation of oceanic and continental surfaces, 



* The question of the animal nature of Eozoon has been practically settled 

 in the negative through the researches of Kinr];, Rowney, Julien, and Mobius ; 

 the elaborate memoir on this subject by tl:e last-mentioned scientist will proba- 

 bly be considered conclusive by most impartial zoologists. The present author 

 has himself examined masses of Eozoon rock in which the network of green 

 mineral, supposed to fill the chamber-cav;ties of the giant foraminii'er, coalesce 

 and merge into a broad band of serpentine. Now, either we have liere a true 

 Eozoon structure or not. If yes, then on what zoological basis, it may be 

 asked, can the gradual convergence of the mflltrating mineral and its final 

 coalescence with a broad band of serpentine be explained ? If the contrary, 

 what necessity is there for invoking the aid of oi'ganic forces m the explanation 

 of a structm-e, Avhen one fully as intricate, and piactically undistinguishable 

 from it, can be shown to be of purely mineral formation 3 



