452 The American Naturalist. [May, 
Among the preceding analyses to be especially mentioned 
are those of three bones from the Permian of Autun (Pleura- 
canthus, Actinodon and Haptodus) those of two bones from the 
Lias of Igornay and of Saint Colombe (Plesiosaurus and Ichthyo- 
saurus), the two bones from chalk of Maestricht (Mosasaurus 
and large turtle). The same effect was remarked by M. Phip- 
son before the Acadamie des Sciences, Oct. 3, 1892. It is, 
therefore, not rare to meet with proportions of fluorine greater 
than that of apatite for the same quantity of phosphorus. 
In some of the experiments heretofore given the proportion 
of fluorine, compared to that of apatite, which is taken for the 
unit, was increased from 1.03 to 1.67. The excess of fluor- 
ide of calcium can be attributed to the action of the alkaline 
fluoride in the solution, alone or mixed with fluoride of cal- 
cium, while the latter has perhaps alone produced the meta- 
morphoses of the bones in which the proportion of fluorine 
does not exceed or perhaps has not even attained that of 
apatite. 
In every point of view, in order to explain the fluoration of 
bone, there is admitted the existence of fluorine in solution in 
the waters which come in contact with these bones; at least 
this is the most plausible supposition, for, on the one hand, the 
fluorides and in particular the fluoride of calcium is suffi- 
ciently prevalent, not only in the crystalline rocks, notably in 
the masses of granite and granulite, but also in a certain num- 
ber of sedimentary rocks, for example, coal-bearing strata in 
arkoses of Burgundy, in the muschelkalk, even in the calcaire 
of Paris, which appear to sufficiently indicate that waters 
charged with fluoride of calcium. can circulate throughout 
these deposits ; and on the other part, the fluoride of calcium 
not being completely insoluble, the infiltrated water, either 
more or less charged with carbonic acid, and with alkaline 
salts and salts of ammonia, could take it up from the rocks 
through which the water traversed and which are more or less 
impregnated with fluorine. 
Many analyses of various waters aun the existence of flu- 
orides in solution even though in minute quantities. Nicklés 
found it in the waters of the Seine at Paris, of the Somme at 
