1895.) Fluorine as a Test for the Fossilization of Animal Bones. 303 
each other, they were practically so—they were in the same 
position, same deposit, and, so far as is possible to determine, 
subject to the same chemical influences: therefore, a compari- 
son between the two = to give an idea of their compara- 
tive ages. 
These bones are shown in one of the alcoves of the Museum 
of the Academy of Natural Sciences, Philadelphia. ‘They are 
fossil bones of extinct animals of the plistocene period. In 
color, texture and general outward appearance they have a re- 
markable similarity as though they belonged together. They 
are well preserved, firm in texture, and of a dark choco- 
late-brown color which has been attributed to ferruginous 
infiltration. They consist of a nearly entire skull of Mega- 
lonyx jeffersonii, teeth of the Megalonyx dissimilis and the’ Erep- 
todon priscus, bones of the Mylodon harlanii, bones and teeth 
of the Mastodon americanus, and teeth of Equus major and 
Bison latifrons. Along with them is the os innominatum of 
a human subject. The question affecting the antiquity of 
man is whether these subjects, the bones of which were found 
together, were, when alive, contemporaneous, and whether 
the evidence of age in one is evidence of age in the other. 
They were all presented to the Academy by Dr. Dickeson 
at the meeting in October, 1846; description thereof is to 
be found in the Proceedings of the Society for that year, vol. 
iii, p. 106. Dr. Dickeson reported at that time that they were 
discovered by him in a single deposit. at the foot of the bluff 
in the vicinity of Natchez, Mississippi. He says, “ The stratum 
that contained these organic remains is a tenacious blue clay 
that underlies the diluvial drift east of Natchez, and which 
diluvial deposit abounds in bones and teeth of the Mastodon 
giganteum ; that they could not have drifted into the position 
in which they were found is manifest from several facts, first 
that the plateau of blue clay is not appreciably acted on by 
those causes that produce ravines in the superincumbent dilu- 
vium; second, that the human bone was found at least two 
feet below the three associated skeletons of the Megalonyz, all 
of which, judging from the position or proximity of their sev- 
‘eral parts, had been quietly deposited in this locality; inde- 
