1-2 PROGRESS <>l I'M. KONTOLOGY n 



out a long space of time. Within the last i \\ 

 .years this lias been done fully in the case of the 

 horse, less completely in the case of the other 

 principal types of the ungulata and of the e;ir- 

 nivMi.i; and all these investigations tend to one 

 general result, namely, that, in any given series, 

 tin- successive members of that series present a 

 gradually increasing specialisation of structure. 

 That is to say, if any such mammal at present 

 inn has specially modified and reduced limbs 

 or dentition and complicated brain, its predecessors 

 in time show less and less modification and reduc- 

 tion in limbs and teeth and a less highly developed 

 brain. The labours of Gaudry, Marsh, and Cope 

 furnish abundant illustrations of this law from the 

 marvellous fossil wealth of Pikermi and the vast 

 uninterrupted series of tertiary rocks in the terri- 

 tories of North America. 



I will now sum up the results of this sketch oi 

 the rise and progress of paleontology. The whole 

 fabric of palaeontology is based upon two proposi- 

 tions : the first is, that fossils are the remains t 

 animals and plants; and the second is, that the 

 stratified rocks in which they are found are sedi- 

 m.'iitary deposits; and each of these propositions 

 undrd upon the same axiom, that like effects 

 imply hi 3. If there is any cause competent 



to produce a fossil stem, or shell, or bone, except 

 a li\inir heinir. then pala-ontnlo ; _ry 1, ;IS no fouiida- 



