236 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



palaeontological observation to note, in a very 

 general way, that the giant forms which have at 

 the same time been highly specialized are never 

 met with at the inception, but only at the end of 

 branches. I have had occasion to quote above 

 numerous examples, and shall confine myself to 

 recalling the gigantic Mastodonsaurus in whom 

 the group of Stegocephala becomes extinguished : 

 the Brontosaurus, the Diplodocus, the Titanosaurus, 

 which terminate the branches of the Sauropod 

 Dinosaurs ; the Titanotherium, the Ancylotherium, 

 the Dinoceras, the Dinotherium, and the Mastodons, 

 whose colossal dimensions announce the end of so 

 many phyla of the Ungulates. Even in the 

 matter of the genera, the Lophiodon lautricense, 

 the Anthracotherium magnum, the Rhinoceros anti- 

 quitatis are the giant and the last representatives of 

 their branches. It would be easy, according to 

 this law, to predict the approaching natural ex- 

 tinction of the Elephant, of the Hippopotamus, of 

 the Whale, and of some other huge species of our 

 present time, even without the intervention of man 

 to hasten their disappearance. Lastly, this phe- 

 nomenon is equally noticeable among the Inverte- 

 brates. We know that the giant forms among the 

 Ammonites, the Pinacoceras, the Arietites, and the 

 P achy discus are found only at the end of their 

 branches ; the Megaladons, the Dicerata, the Cap- 

 rince reckon their hugest species in the most recent 

 levels of their geological duration. It would be 

 easy to recall many other similar cases. 



The curious remark was long since made that it 

 is at the very moment when the species of a group 



