DINOSAURS. 107 



shield or carapace of certain extinct armadillos known as Glypto- 

 donts (see Chapter XII.). A specimen of such a shield is .to be 

 seen in the collection at South Kensington (Wall-case 4). It is to 

 be hoped that, some day, further remains of the Polacanthus will 

 be brought to light, so that a restoration may become possible. 

 Dr. Man tell had already pointed out certain analogies between 

 Iguanodon and the huge extinct sloths of the South American 

 continent, that flourished in the much more recent Pleistocene 

 period ; and this idea is now considerably strengthened by the 

 later discoveries of armoured Dinosaurs. These are his words : 

 " In fine, we have in the Iguanodon the type of the terrestrial 

 herbivora which, in the remote epoch of the earth's physical 

 history termed by geologists the age of Reptiles, occupied the 

 same relative position in the scale of being, and fulfilled the same 

 general purposes in the economy of nature, as the Mastodons, 

 Mammoths, and Mylodons (extinct sloths) of the Tertiary period, 

 and the existing pachyderms." 



It is, perhaps, one of the most interesting discoveries of modern 

 geology, that certain races of animals now extinct have in various 

 ways assumed some of the characteristics presented by animals 

 much higher in the scale of being, that flourish in the present day. 

 It seems as if there had been some strange law of anticipation at 

 work, if we may venture so to formulate the idea. It has already 

 been shown how the great saurians Ichthyosaurus and Plesiosaurus 

 presumed to put on some of the characters of whales, and to play 

 their role in nature, thougli they were only reptiles ; how the 

 carnivorous Dinosaurs acquired teeth like those now possessed by 

 lions and tigers, which also are mammals ; and now we find 

 herbivorous Dinosaurs imitating the Glyptodon, an armadillo 

 that lived in South America almost down to the human period. We 

 shall not lose sight of this very interesting and curious discovery, 

 for other cases will present themselves to our view in future 

 chapters. The reader might ask, " If reptiles were able in these 

 and other ways to imitate the mammals of to-day, or of yesterday. 



