THE EUROPEAN SEAS. 



247 



this is the zone of the "free-swimmers" — Pteropods, 

 Nucleobranchs, Pelagic Cephalopods, and Crusta- 

 ceans. The depositions of all past times present 

 every gradation of bathymetrical distribution, down 

 to the " Azoic zones " of depth, and the mere 

 geologist must beware not to misinterpret the evi- 

 dence presented to him, and suppose that some old 

 world of waters was without life, merely because he 

 finds no traces of it. Still less, on such negative 

 evidence, must he speculate as to the " dawn of 

 life," " Protozoic forms," and " Primordial zones." 

 The history of our own seas, and of all seas, teaches 

 us that there is a law of proportion in the classes 

 and orders of the living things that dwell there, 

 and that the presence of one form is safe ground of 

 inference as to the co-existence of countless others. 

 There may be no marine fauna older than that 

 which the palaeontologist has termed " Palaeozoic," 

 but it is most unphilosophical to suppose that or- 

 ganic life commenced with, and was limited to, 

 Lingulce in the latitude and longitude of Festiniog. 



