288 PALAEONTOLOGY. 



animal part is not allowed to putrefy, it appears only to be dissolved 

 into a kind of mucus, and can be discovered by dissolving the earth in 

 an acid ; when a shell is treated in this way, the animal substance is 

 not fibrous or laminated, as in the recent shell, but without tenacity, 

 and can be washed off like wet dust ; in some, however, it has a slight 

 appearance of flakes. 



" In the shark's tooth, or glosso-petra, the enamel is composed of 

 animal substance and calcareous earth, and is nearly in the same quan- 

 tity as in the recent ; but the central part of the tooth has its animal 

 substance in the state of mucus interspersed in the calcareous matter. 



" In the fossil bones of sea animals, as the vertebrse of the whale, the 

 animal part is in large quantity, and in two states ; the one having 

 some tenacity, but the other like wet dust : but in some of the harder 

 bones it is more firm. 



" In the fossil bones of land animals, and those which inhabit the 

 waters, as the sea-horse, otter, crocodile, and turtle, the animal part is 

 in considerable quantity. In the stag's horns dug up in Great Britain 

 and Ireland, wben the earth is dissolved, the animal part is in con- 

 siderable quantity, and very firm. The same observations apply to the 

 fossil bones of the elephant found in England, Siberia, and other parts 

 of the globe ; also those of the ox kind ; but more particularly to their 

 teeth, especially those from the lakes in America, in which the animal 

 part has suffered very little ; the inhabitants find little difference in 

 the ivory of such tusks from the recent, but its having a yellow stain ; 

 the cold may probably assist in their preservation. 



" The state of preservation will vary according to the substance in 

 which they have been preserved ; in peat and clay I think the most ; 

 however, there appears in general a species of dissolution ; for the 

 animal substance, although tolerably firm, in a heat a little above 100° 

 becomes a thickish mucus, like dissolved gum, while a portion from the 

 external surface is reduced to the state of wet dust. 



" In encrusted bones, the quantity of animal substance is very 

 different in different bones. In those from Gibraltar there is very 

 little ; it in part retains its tenacity, and is transparent, but the super- 

 ficial part dissolves into mucus. 



" Those from Dalmatia give similar results when examined in this 

 way. 



" Those from Germany, especially the harder bones and teeth, seem 

 to contain all the animal substance natural to them : they differ how- 

 ever among themselves in this respect. 



" The bones of land animals have their calcareous earth united with 

 the phosphoric acid instead of the aerial, and, I believe, retain it when 



