9 8 PERIOD IV. 



as exact as astronomy. The hope may have been 

 chimerical, but emphasis on this side was not altogether 

 out of place in the generation of Geoffrey St. Hilaire 

 and Oken. 



If the great master who laid the foundations of palae- 

 ontology could revisit the scene of his former labours, 

 he would find that many strange things had happened 

 since the appearance of his Ossemens Fossiles. He would 

 perhaps be stupefied at first to discover how little is 

 now made of the Revolutions of the Earth, the proofs 

 of which had seemed to him unimpeachable, while the 

 conjectures about the development of new races, which 

 in his own day had been almost negligible, have proved 

 to be anticipatory of fundamental biological truths. 

 The first shock over, one can imagine the zest with 

 which he would strive to combine the familiar facts 

 into a body of new doctrine. The ungulates, recent 

 and fossil, would of course interest him particularly. 

 He would recognise the gradations of structure which 

 run through the whole order, branching and crossing 

 in all directions; gradation in the number of the 

 toes, in the rearing of the body more and more upon 

 the toe-tips, in the progressive complication of the teeth. 

 One chain of examples would lead from the shallow, 

 tuberculate molar of the pig to the molar of the horse 

 or ruminant, deep and massive, with crescentic enamel- 

 folds ; another would illustrate the gradual development 

 of tusks from ordinary incisors or canines ; a third 

 series would show the steps by which the primitive 

 ungulate dentition became reduced to the dentition of 

 the elephant, with only a single pair of incisors, enlarged 

 into tusks several feet long, with no canines but molars 

 of great weight, complicated by extreme folding. It 

 would surprise and delight him to compare the almost 



