314 Prof. J. Van der Hoeven on the Succession and 



there can be no reason given why their remains, their bones &c., 

 were never found together with the remains of the extinct spe- 

 cies alluded to. Perhaps the first thesis seems not so clear — 

 that those species which we find in the strata of different aqueous 

 rocks and deposits are truly extinct. Some may be disposed to 

 ask whether our survey of the now living organic world is so 

 complete that we know all the species. This is certainly not the 

 case ; but the chances of discovering species similar to those we 

 know as yet only as fossils decrease daily, and the whole objec- 

 tion loses its strength because geological investigations teach us 

 that the animals and plants of older strata are specifically dif- 

 ferent from those of recent ones. Thus not only one series of 

 organisms is extinct, but there are several such series, the one 

 succeeding the other. Species of the difi"erent tertiary strata 

 are different from each other. All these are diff'erent from those 

 of the Chalk formation ; those of the Chalk formation are unlike 

 those of the Oolitic series ; others, again, are to be found in the 

 strata of the New Red Sandstone, others in the Coal formation 

 &c., all differing. 



That some species became extinct seems in general a fact that 

 is not so strange as that some species originated in succession — 

 that there were consecutive and distinct creations of organic 

 forms. Of the first fact we do not want examples, even in 

 recent periods, within the three last centuries of history. I 

 may refer to the well-ascertained fact of the extinction of the 

 Dodo — a bird recorded to have been seen by several travellers, 

 and represented in various pictures and prints. Greater still is 

 the number of instances of local exterminations, local extinctions 

 of species. In many civilized parts of Europe several species 

 have now totally disappeared, which formerly were not uncom- 

 mon in the same localities. At the time of Xerxes lions lived 

 in Greece, and attacked the camels of his army*. Even a cen- 

 tury and a half after that time, lions are mentioned by Aristotle 

 as living in Europe f. In many parts of Europe the beaver was 

 common in the middle ages, where it is now entirely unknown. 

 In Wales and Scotland the bear was found in the first ten cen- 

 turies of the Christian era ; and even the wolf was not entirely 

 extirpated till about the end of the 17th century J. The extinc- 

 tion of species in prsehistorical times, in the different geological 

 periods which elapsed before the appearance of man, differs only 

 in being more general — we should almost say, in being total, if 

 the investigations of Ehrenberg did not teach us that some 



* Herodot. vii. 125, 126. t Hist. Animal, viii. 



:|: In 1680, when the last wolf fell by the hand of the famous Sir Ewen 

 Cameron. (Thos. Pennant's 'British Zoologj-,' new ed., London, 1812, 

 p. 88.) . , 



