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PRO CE EE DINGS OF THE GEOLOGICAL SOCIETY. 



tion of the land or sea was scanty at that era, but because in general 

 the preservation of any relics of the animals or plants of former times 

 is the exception to a general rule. Time so enormous as that con- 

 templated by the geologist may multiply exceptional cases till they 

 seem to constitute the rule, and so impose on the imagination as to 

 lead us to infer the non-existence of creatures of which no monu- 

 ments happen to remain. Professor Edward Forbes in his Lectures 

 on Paleontology has remarked, that few geologists are aware how 

 large a proportion of all known species of fossils are founded on single 

 specimens, while a still greater number are founded on a few indivi- 

 duals discovered in one spot. This holds true not only in regard to 

 animals and plants inhabiting the land, the lake, and the river, but 

 even to a surprising number of the marine mollusca, articulata, and 

 radiata. Our knowledge, therefore, of the living creation of any 

 given period of the past may be said to depend in a great degree on 

 what we commonly call chance, and the casual discovery of some 

 new localities rich in peculiar fossils may modify or entirely over- 

 throw all our previous generalizations, so long as they are based on 

 the supposed non-existence at former epochs of the fossil representa- 

 tives of large families or classes of plants and animals. 



When we contrast the botany and zoology of primary and se- 

 condary strata with those of tertiary formations, it is more especially 

 incumbent on us to make due allowance for a comparatively deficient 

 acquaintance with the ancient deposits, which are more and more ex- 

 clusively marine in proportion as we depart farther from those periods 

 during which our existing continents were built up. They are more 

 marine, not because the ocean was more universal in times past, 

 but because, when we carry back our retrospect to epochs so distant 

 that entire continents have been since submerged, we are less favour- 

 ably placed for exploring strata thrown down in lakes and estuaries 

 or near the shore. In studying the tertiary strata, as I before 

 remarked, we have opportunities of becoming more thoroughly ac- 

 quainted with the remains of the flora and fauna which flourished 

 in a great variety of stations, and besides in these more modern rocks 

 the imbedded fossils are less obliterated by the destroying hand of 

 time. If we conceal or extenuate such circumstances when we argue 

 with an opponent who believes that the primary or secondary fauna 

 was as highly developed as the tertiary, we take an unfair advantage 



