906 The American Naturalist. [November, 
permanent form or condition as a fossil. The history and dis- 
cussion of these three steps form a complete history of fossiliza- 
tion. 
The placement of an object will vary in its conditions, ac- 
cording to the habitat of the organism. The most general 
distinction will be between terrestrial (for the most part, ver- 
tebrates) or marine (for the most part, invertebrates) organ- 
isms, where the contrasted conditions involve contrasted hab- 
its and varying accidents and associations. Upon the surface 
of the land animals may die in numbers, either upon plains or 
elevated regions, or in the depths of forests, but the rapid ac- 
tion of decay, or the ceaseless activity of flesh-eating insects 
may soon dissipate their remains, even when the bony skeleton 
is imposing and highly developed. 
The bones of buffalo remain upon the western prairies for 
four or five years, at least, in a recognizable condition.’ In 
the region about Miles City, Montana, the buffalo abounded as 
late as 1880. After that time, the remorseless zeal of hunters 
and the avarice of trade had reduced their numbers and 
brought them to the verge of extinction. According to W. T. 
Hornaday, “over the whole of this vast area their bleaching 
bones lie scattered,” and many of these have certainly been 
exposed to the weather for a period of four years, while their 
condition when collected warranted the expectation of their 
remaining sensibly unchanged many more. (See the Extermi- 
nation of the American Bison, Smithsonian Report, 1887, p. 
508.) 
Upon the visit of the Challenger to Hard Island, of the Mc- 
Donald ‘Group in the Antarctic seas, Prof. Moseley observes 
that upon a sandy glacial plain there were strown “bones of 
the sea-elephant and sea-leopard, those of the former being 
most abundant. There were remains of thousands of skele- 
tons, and I gathered a good many tusks of old males. The 
bones lay in curved lines, looking like tide-lines, on either side 
of the plain above the beaches, marking the rookeries of old 
5It is interesting to note that Captain Stansbury observes in his Exploration 
and Survey of Great Salt Lake, that “ carcasses of buffalo left on the open prairie 
are not unfrequently completely cured, or rather ‘ mummified’ in the sun,so that - 
they seldom exhibit any sign of decay.” 
