oo K 



Pampean Formation. part n. 



with Mollusca, all of which are still living species ; but 

 analogous facts have been observed in N". America and 

 in Europe. In the first place, it should not be over- 

 looked, that most of the co-embedded shells have a 

 more ancient and altered appearance than the bones. 

 In the second place, is it probable that numerous bones 

 not hardened by silex or any other mineral, could have 

 retained their delicate prominences and surfaces perfect 

 if they had been washed out of one deposit, and re- 

 embedded in another ; — this later deposit being formed 

 of large, hard pebbles, arranged by the action of currents 

 or breakers in shallow water into variously curved and 

 inclined layers ? The bones which are now in so perfect 

 a state of preservation, must, I conceive, have been 

 fresh and sound when embedded, and probably were 

 protected by skin, flesh, or ligaments. The skeleton of 

 the Scelidotherium indisputably was deposited entire : 

 shall we say that when held together by its matrix it 

 was washed out of an old gravel -bed (totally unlike in 

 character to the Pampean formation), and re-embedded 

 in another gravel-bed, composed (I speak after careful 

 comparison) of exactly the same kind of pebbles, in 

 the same kind of cement ? I will lay no stress on the 

 two cases of several ribs and bones of the extremities 

 having apparently been embedded in their proper 

 relative position : but will anyone be so bold as to affirm 

 that it is possible, that a piece of the thin tesselated 

 armour of a Dasypoid quadruped, at least three feet 

 long and two in width, and now so tender that I was 

 unable with the utmost care to extract a fragment more 

 than two or three inches square, could have been washed 

 out of one bed, and re-embedded in another, together 

 with some of the small bones of the feet, without having 

 been dashed into atoms ? We must then wholly reject 



