PENROSE.] BONE BEDS. 127 
much larger and more plentiful in Europe than in North America. The 
reason for this seems to be that in this country there were none of the 
earnivora, such as the jackals and hyenas, which have the habit of drag- 
ging their prey to their lairs. Consequently our caverns, notwithstand- 
ing their abundance and the great number of animals which have lived 
about them, are generally wanting in the extensive osseous breccias 
which characterize many caves in England, France, Germany, Hun- 
gary, Italy, and many other parts of Europe. 
Many of the caves of the Southern States have been much resorted 
to by bats. The excrements of these creatures, together with the bones 
of those that have died there, have in many cases formed extensive 
beds of phosphatic and nitrogenous matter. 1 During the early part of 
this century, and during the civil war, saltpeter was extensively man- 
ufactured from them, and some of them have also been worked as a 
source of phosphate of lime. 
LACUSTRINE DEPOSITS. 
These deposits occur generally about the swampy margins of salt 
licks, as at Big Bone Lick in Kentucky 2 , and in the ancient lake de- 
posits west of the Mississippi Eiver, as in the Mauvaises Terres of Ne- 
braska. Similar beds are also found in many parts of Europe. The 
bones found in such localities are the remains of animals which came to 
the swamps to lick the salt found there, or in search of refuge. Many 
died natural deaths, while others were mired in the boggy earth, and, 
being unable to extricate themselves, perished. In this way bones ac- 
cumulated often in very considerable quantities. 
These deposits, as well as those of the cave class, are generally too 
limited in extent to be of any commercial importance. 
1 These deposits have been described under the heading of Guanos. 
2 An account of this deposit may be fouud in an appendix to Mr. J. A. Allen's mono- 
graph on The History of the Buffalo, in the memoirs of the Kentucky Geological Sur- 
vey, Vol. I, 1876. 
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