326 Pampean Formation. paet n. 



are changed throughout into a white, soft, fibrous sub- 

 stance; others have the space between the external 

 walls, either hollow, or filled up with crystalline car- 

 bonate of lime. 



The remains of the extinct mammiferous animals, 

 from the two gravel beds have been described by Pro- 

 fessor Owen in the ' Zoology of the Voyage of the Beagle : ' 

 they consist of 1st, one nearly perfect head and three 

 fragments of heads of the Megatherium Cuvierii; 2nd, 

 a lower jaw of Megalonyx Jeffersonii • 3rd, lower jaw 

 of Mylodon Darwinii; 4th, fragments of a head of 

 some gigantic Edental quadruped ; 5th, an almost entire 

 skeleton of the great Scelidotherium leptocejphalum, 

 with most of the bones, including the head, vertebrae, 

 ribs, some of the extremities to the claw-bone, and even, 

 as remarked by Professor Owen, the knee-cap, all nearly 

 in their proper relative positions; 6th, fragments of 

 the jaw and a separate tooth of a Toxodon, belonging 

 either to T. Platensis, or to a second species lately dis- 

 covered near Buenos Ayres ; 7th, a tooth of^JEquus 

 curvidens ; 8th, tooth of a Pachyderm, closely allied to 

 Palaeotherium, of which parts of the head have been 

 lately sent from Buenos Ayres to the British Museum ; 

 in all probability this pachyderm is identical with the 

 Macrauchenia Patachonica from Port S. Julian, here- 

 after to be referred to. Lastly, and 9thly, in a cliff of 

 the red clayey bed (B), there was a double piece, about 

 three feet long and two wide, of the bony armour of a 

 large Dasypoid quadruped, with the two sides pressed 

 nearly close together : as the cliff is now rapidly wash- 

 ing away, this fossil probably was lately much more 

 perfect ; from between its doubled-up sides, I extracted 

 the middle and ungueal phalanges, united together, of 

 one of the feet, and likewise a separate phalang : hence 

 one or more of the limbs must have been attached to 



