INTRODUCTION. 



and newer pliocene periods ; and to speak of the sum of the 

 present observations under the term " law," may, perhaps, 

 be deemed premature. But the generalizations first enun- 

 ciated in my Report to the British Association in 1844, 

 seemed to be sufficiently extensive and unexceptionable to 

 render them of importance in a scientific consideration of 

 the present distribution of the highest organized and last- 

 created class of animals ; and to show that, with extinct as 

 with existing Mammalia, particular forms were assigned to 

 particular provinces, and, what is still more interesting and 

 suggestive, that the same forms were restricted to the same 

 provinces at the pliocene periods, as they are at the present 

 day* 



In carrying back the retrospective comparison of recent 

 and extinct Mammals to those of the eocene and oolitic 

 strata, in relation to their local distribution, we obtain indi- 

 cations of extensive changes in the relative position of sea 

 and land during those epochs, in the degree of incongruity 

 between the generic forms of the Mammalia which then 

 existed in Europe, and any that actually exist on the great 

 natural continent of which Europe now forms part. It 

 would appear, indeed, from our present knowledge, that 

 the further we penetrate into time for the recovery of 

 extinct Mammalia, the further we must go into space to 

 find their existing analogues. To match the eocene Pa- 

 laeotheres and Lophiodons, we must bring Tapirs from 

 Sumatra or South America, and we must travel to the an- 

 tipodes for Myrmecobians and Dasyures, the nearest living 



* Humboldt, in citing the Mylodon, Dinornis, and Diprotodon, briefly repeats 

 my generalizations from those discoveries, and says : " Es herrscht in Siidame- 

 rika und in den Australandern eine grosse Aehnlichkeit zwischen den dort 

 lebenden und den untcrgegangenen Thieren." " In South America and the 

 Australian lands there prevails a great resemblance between the existing and 

 the extinct animals." Kosmos, 8vo. 1845, p. 303. 



