THE ORIGIN OF THE OLDEST FOSSILS, ETC. 281 



flora for an organism to gain superiority by seizing upon an advan- 

 tageous site or by acquiring peculiar habits, for one place was like 

 another, and peculiar habits could count for little in comparison 

 with accidental space relations. After the fauna of the surface 

 had been enriched by all the marine animals which have become 

 secondarily adapted to pelagic life^ competition with those improved 

 forms brought about improvements in those which were strictly 

 pelagic in origin, like the siphonophores, and those wanderers 

 from the bottom introduced another factor into the evolution of 

 pelagic life, for their bodies have been utilised for protection or 

 concealment and in other ways, and we now have fishes which 

 hide in the poison curtain of Physalia, Crustacea which live in the 

 pharynx of Salpa or in the mouth of the menhaden, barnacles and 

 sucking fish fastened to whales and turtles, besides a host of exter- 

 nal and internal parasites. The primitive ocean furnished no such 

 opportunity, and the conditions of pelagic life must at first have 

 been very simple, and while competition was not entirely absent 

 the possibilities of evolution must have been extremely limited, 

 and the progress of divergent modification very slow, so long as 

 all life was restricted to the waters of the ocean. 



There can be no doubt that floating life was abundant for a 

 long period when the bottom was uninhabited. The slow geological 

 changes by which the earth gradually assumed its present charac- 

 ter present a boundless field for speculation, but there can be no 

 doubt that the surface of the primeval ocean became fit for living 

 things long before the deeper waters or the sea floor, and during 

 this period the proper conditions for the production of large and 

 complicated organisms did not exist, and even after the total 

 amount of life had become very great it must have consisted of 

 organisms of small size and simple structure. 



Marine life is older than terrestrial life, and as all marine life 



has shaped itself in relation to the pelagic food supply, this itself 



is the only form of life which is independent, and it must therefore 



be the oldest. There must have been a long period in primeval 



times when there was a pelagic fauna and flora rich beyond limit 



in individuals, but made up of only a few simple types. During 



this time the pelagic ancestors of all the great groups of animals 



were slowly evolved, as well as other forms which have left no 



International Journal of Microscopy and Natural Science. 



Third Series. Vol. V. u 



