1870.] 231 [Staler. 



stream, but the style of wear which comes from being stamped and 

 trodden on. The appearance of the worn surfaces reminds me of that 

 seen on fragments .of bone from Big Bone Lick, which have been 

 ground by the trampling of the large pachyderms and ruminants 

 which frequented that swamp. Sometimes these nodules do not 

 make up more than a considerable fraction of the bed, the remainder 

 being sand, pebbles, or the marl of the character found on the bed 

 beneath. Again, the nodules are so crowded in the bed that they are 

 soldered together into one mass, with scarce any interspaces between 

 the separate concretions. 



Mingled with the concretions there is found a very variable quantity 

 of fossil vertebrate remains; by far the greater part of these consist 

 of exceedingly worn fragments of cetacean bones and sharks' teeth 

 and vertebras, both clearly of the same species as those found lower 

 down in the marls in the same section- Mingled with these, but 

 comparatively rarely found, are the bones of a fossil horse, pig, mas- 

 todon, and bones and utensils of man. These last named fossils are 

 almost always in a state of preservation, widely different from that of 

 the remains of the cetaceans and selachians with which they are 

 mingled. Their appearance indicates a comparatively recent inhu- 

 mation. 



Chemical analysis shows us that the nodules of this deposit contain 

 the greatest quantity of phosphate of lime, the quantity varying at 

 different points from forty to nearly seventy per cent. The first and 

 most natural seeming explanation of the large amount of this salt, 

 is that it is derived from the bones and excrements of the animals 

 whose remains are found in the bed. But the points where the most 

 bones are found are not those where the phosphate deposit is thickest 

 or richest. At Chisholm's Island, on the waters of St. Helena Sound, 

 where the bed has the greatest development yet discovered, and. 

 where the analysis shows more phosphoric acid than at some of the 

 localities the richest in bones, the remains of vertebrate animals are 

 very rarely found. It is not too much to say that at this locality not 

 one part in ten thousand of the mass is composed of vertebrate re- 

 mains. Nor can we assume that the mass of phosphoric acid has been 

 furnished by the decay of bones which have been utterly broken 

 down; in that case we should have the remaining bones showing all 

 degrees of preservation. This, however, is not the case; the frag- 

 ments, though usually much worn, retain their structure very well. 

 Although I went upon the ground with a disposition to regard the 



