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CHARLES B. WARRING, M.A., PH.D., ON 



new or changing influences, but only within certain limits, when 

 these are reached they endure the strain no farther. The bow 

 bent too far breaks. Probably it was so in those early periods. 

 The weaker went first, at last all went, and then geologists 

 Teport a general extermination. 



The lower forms of life now are less sensitive to such influences 

 than those of higher rank. It is reasonable to believe that the 

 same was the case in geological times ; and if so, may we not 

 find in this fact an explanation of the greater length of the 

 earlier periods as indicated by their fossil remains ? 



The progress of improvement would seem to have reached its 

 limit, so far as soil and atmosphere are concerned, by the close 

 of the Miocene, for, according to De la Saporta, Le Monde cles 

 Plantes, page 380, the flora of the Pliocene is still with us. He 

 says : — " The principal groups, and even the genera of the plants 

 which constitute the immense majority of our actual floras, were 

 established from their beginning, probably even before the end 

 of the Tertiary age, in the limits which they now occupy," and 

 again, he says, page 342, " Let us not forget to remark that the 

 European species still living occupy their actual country since 

 the close of the Pliocene. They affect with secondary variations 

 and shadings more or less pronounced the same characteristics 

 as in our own day." If in this Saporta be right, and one may 

 judge by the sameness of plant life from that time onward, 

 neither atmosphere nor soil underwent any further essential 

 improvement.* 



There were, however, great changes in the animal world. 

 Dana probably puts it too broadly when he says on page 518 

 of his revised Manual of G-eology, "All the fishes, reptiles, 

 birds and mammals of the Tertiary are extinct." But I think 

 it is beyond question that an enormous proportion of the Tertiary 

 vertebrates have ceased to exist. In the Quaternary the fishes, 

 reptiles, birds and mammals were mainly of new species. At 

 its close the mammals disappeared, the others are with us yet. 

 In the next or present period, we find in place of the mammals 

 of the Quaternary, the cattle and beasts of to-day. 



The extermination of the Pliocene fauna seems probably to 

 have been due to the great climatic changes which followed. 

 It is difficult to see why the large, well armed, and well 

 armoured mammals of the Quaternary became extinct. Had 



* This is not quite correct. The wonderful change in the prevalent 

 flora from monocotyledonous to dicotyledonous plants took place at the 

 close of the Lower Cretaceous period. — Ed. 



