1395.] Fluorine as a Test for the Fossilization of Animal Bones. 719 
origin of the frenate type from an earlier type which was es- 
sentially jugate, but which possessed frenulum-like structures 
of a character to be easily developed, by selection, into the ex- 
isting highly specialized frenate condition of the wings of the 
Noctuide and others. 
In conclusion, I may add that every attempt I have yet 
made to study, in a comparative way, the morphology of the 
three insect groups mentioned in this paper, has afforded in 
each succeeding instance stronger basis for a belief in the close 
phyletic relationship of the groups, a belief shared with, of 
course, and already expressed by many others. 
Stanford University, Calif. 
ON THE PRESENCE OF FLUORINE AS A TEST FOR 
THE FOSSILIZATION OF ANIMAL BONES. 
By Dr. THomas WItson. 
(Continued from page 456, Vol. XXIX). 
Appreciating the importance of the discoveries made in 
France in regard to the proportion of fluorine in animal bones 
as a test of their fossilization and antiquity, I determined to 
make a further attempt in the investigation by analysis of the 
bones, human and mylodon, found by Dr. Dickeson at Natchez, 
as heretofore described (page 303). Tothat end, I made appli- 
cation to Dr, Samuel G. Dixon, Curator of the Academy of 
Natural Sciences of Philadelphia, for specimens of the two 
bones to be subjected to analysis with a view to the determina- 
tion of their respective proportions of fluorine. Dr. Dixon 
kindly presented my application, and it was allowed. In due 
course I received the fragments from the two respective bones. 
Professor R. L. Packard was engaged in the laboratory in the 
U. S. National Museum making a series of mineral and rock 
analyses, we had, together, become acquainted with Mons. Car- 
