446 The American Naturalist. [May, 
Devonian. 
1. Asterolepis Bony plates from the Devonian of Livonia, 
Russia. Dense, brownish-black, becoming reddish-gray by 
ignition. Very little carbonate of lime, notable quantity of 
quartz with traces of chlorine. 
Organic matter, : : ; fi 5.20 
Ash: Oxide of iron, . ‘ i i 3.02 
Phosphoric acid, . $ : i 29.50 
Fluorine, . EEE ; 2.59 lR tio. 0.98 
Fluorine of apatite, tee EO earls a 
Silurian. 
The debris of fish extracted from a ferruginous bone breccia 
of the inferior silurian of Canyon City, Colorado, U. S. A., re- 
ported in 1891 by Mons. Albert Gaudry, after his journey to 
the Rocky Mountains. 
Organic matter, eee Es ‘ : 5.67 
Ash: Oxide of iron, . P á o ray kt 
Phosphoric acid, ; ; A 32.63 
Fluorine, ; 
2.72 . 
Fluorine of apatite, 2.90 j gia ata 
General observations—Bones of the same age present great 
differences in their composition; but one can, nevertheless, 
conclude from the foregoing series of analyses, in a general 
fashion, that the fossilization is accompanied by an important 
increase in the proportion of carbonate of lime, of oxide of 
iron and fluorine. 
For the first two of these elements, the augmentation is too 
irregular, too usually affected by special influences of the de- 
posit where they were buried, to enable us to indicate with 
certainty the true fossil state of the bone. We frequently ob- 
serve, also, a high proportion of carbonate of lime and of ox- 
ide of iron in bones which have been buried for a time, either 
longer or shorter, but which, after all, belong to the modern 
period. 
