724 The American Naturalist. [August, 
those of Mons. Carnot, that the results are comparative and not 
absolute. The value of our investigations lies in showing that 
if the bones of the mylodon and the man were originally de- 
posited together, and were practically the same age, they must 
have been subjected to substantially the same chemical influ- 
ences, they would show practically the same analyses, and the 
comparison between their respective constituents should be 
substantially the same. Thus is afforded the great desiderata 
of a means of comparison between the human and the animal 
bone. As it is known that the mylodon was to a certain ex- 
tent an ancient animal, if the human bone, when compared 
with that of the mylodon showed an equal amount of fluorine 
together with the concomitants of fossilization, it is evidence 
that they are of the same antiquity. 
The relations between the various chemical constituents of 
the two bones are shown in the following table: 
Mylodon Man 
Fluorine, . i 0.28 0.38 
Fluorine énloulated i apatite,” $ 2.37 1.85 
Ratio, ; ; j ; ; 0.102 0.205 
Phosphoric acid, : i : . 26.59 20.77 
Fluorine, . A ; : ; : 0.28 0.38 
Ratio, ; , : i : i 94.96 -54.70 
Organic matter, : i 25.55 21.43 
Oxide of iron and alimi ; é 7.75 6.50 
From these tables the following comparisons may be made: 
The fluorine in the mylodon was 0.28, in man 0.38, the ratio 
between the quantity of fluorine in the bone and to that of an- 
apatite having an equal amount of phosphoric acid was, for 
the mylodon 0.102, for the man 0.205. A reference to the tables 
on pages 313 and 447 will show that for modern bones, the 
average as calculated from twelve specimens, is 0.058. By the 
same table the Quaternary bones were shown to be 0.36. It 
would appear from a comparison, that the bones of the man and 
the mylodon subjects of the present analyses are approximately 
between modern bones and those of the Quaternary period. 
