Rev. Mr WhewelFs Address to the Geological Society. 157 



in which country he conceives that he has detected terraces 

 which exhibit the beaches of the lakes when the level of their 

 surface was more elevated than they are at present. I must 

 refer also to Mr. Bollaert's paper on alluvial accumulations con- 

 taining large masses of silver ore in Peru. And, finally, I 

 have to direct your attention to the very curious information 

 respecting the geology of South America, which we have re- 

 ceived from Mr Darwin. In a communication made to us, he 

 gave a very striking view of the structure of a large portion of 

 that continent ; and, as I have already had occasion to observe, 

 he has brought to this country the remains of various fossil ani- 

 mals of entirely new kinds, of exceeding interest to the zoologist 

 as well i^s the geologist. I need only remind you of the gigantic 

 mammifer which has been reconstructed in idea by Mr Owen, 

 upon the evidence of a fossil skull, and has been named by him 

 the Toxodon Platensis. This animal, although a Rodent^ ac- 

 cording to its dental characters, in other respects manifests an 

 affinity to the Pachyderms ; and also to the Dinotherium, and 

 to the cetaceous order. Many other fossil animals have been 

 discovered in South America ; and all, from their magnitude, 

 fitted to excife our wonder, when we compare the diminutive 

 size of the present races of animals which inhabit that country. 

 The animal remains found by Mr Darwin comprise, besides 

 the Toxodon, which extraordinary animal was as large as a 

 hippopotamus, — (2, 3, 4, 5, 6.) the Megatherium, and four or 

 five other large Edentata ; — (7.) an immense Mastodon ; — (8.) 

 the Horse ; — (9.) an animal larger than a horse, and of very 

 singular character, of which a fragment of the head has been 

 found; — (10, 11, 12.) parts of Rodents, one of considerable 

 size ; — (13.) a Llama, or Giianaco, fully as large as the Camel. 

 But I should very ill convey my impression of the great 

 value of the researches of Mr Darwin, by any enumeration of 

 special points of geology or palaeontology on which they have 

 thrown light. Looking at the general mass of his results, the 

 account of which he has been kind enough to place in my hands, 

 I cannot help considering his voyage round the world as one of 

 the most important events for geology which has occurred for 

 many years. We may think ourselves fortunate that Capt. 

 Fitz-Roy, who conducted the expedition, was led, by his en- 



