1833.] BAHIA BLAXCA. 81 



CHAPTEE V. 



fiahia Blanca Geology Numerous gigantic extinct Quadrupeds Recent 

 Extinction Longevity of Species Large Animals do not require a luxu- 

 riant vegetation Southern Africa Siberian Fossils Two Species of 

 Ostrich Habits of Oven-bird Armadilloes Venomous Snake, Toad, 

 Lizard Hybernation of Animals Habits of Sea-Pen Indians Wars and 

 Massacres Arrow-head, antiquarian Relic. 



BAHIA BLANCA. 



THE Beagle arrived here on the 24th of August, and a week after- 

 wards sailed for the Plata. With Captain Fitz Roy's consent I 

 was left behind, to travel by land to Buenos Ayres. I will here 

 add some observations, which were made during this visit and 

 on a previous occasion, when the Beagle was employed in sur- 

 veying the harbour. 



The plain, at the distance of a few miles from the coast, 

 belongs to the great Pampean formation, which consists in part 

 of a reddish clay, and in part of a highly calcareous marly rock. 

 Nearer the coast there are some plains formed from the wreck 

 of the upper plain, and from mud, gravel, and sand thrown up 

 by the sea during the slow elevation of the land, of which eleva- 

 tion we have evidence in upraised beds of recent shells, and in 

 rounded pebbles of pumice scattered over the country. At 

 Punta Alta we have a section of one of these later-formed little 

 plains, which is highly interesting from the number and extra- 

 ordinary character of the remains of gigantic land-animals em- 

 bedded in it. These have been fully described by Professor 

 Owen, in the Zoology of the voyage of the Beagle, and are depo- 

 sited in the College of Surgeons. I will here give only a brief 

 outline of their nature. 



First, parts of three heads and other bones of the Megathe- 

 rium, the huge dimensions of which are expressed by its name. 

 Secondly, the Megalonyx, a great allied animal. Thirdly, the 

 Scclidotlierium, also an allied animal, of which I obtained a 



