1896.] Fossils and Fossilization. 907 
times, and teaches of slaughter of the sealers. Some bones 
occurred far up on the plain, the elephants having, in times of 
security, made their lairs far from the water’s edge. A few 
whales’ vertebre were also seen lying about.” In dry or tem- 
perate regions, bones resist disintegration indefinitely. 
In Canada, at Helena, a vast collection of thousands of 
buffalo skulls are seen, the enduring vestiges from a slaughter 
of wild buffalo surrounded by Indians at that place. 
The structure of bone in exposures where the climate passes 
through severe extremes is an element of weakness in their 
preservation. Winding canals (Haversian canals) traverse the 
substance of hard bone and secure connection with a series of 
lacunae, distributed through the substance of the bone, by 
means of minute tubuli (canaliculi). These tubuli radiate in 
complex tangles from the lacunae. Sarcodic or marrow-like 
matter permeates these delicate passages, and, in the Haver- 
sian canals, blood corpuscles circulate. In the less dense por- 
tions of bones, as the extremities of the leg- and arm-bones, 
head-bones, etc., a cancellated or cellular structure forms a 
porous area, while long cavities (marrow-cores) filled with 
marrow occupy the axes of the longer bones. The decomposi- 
tion of these organic contents at first weakens bone, and com- 
mences an insidious process of splitting. Subsequently the 
bone becomes filled with water, and the labyrinthine chain of 
chambers, small and large, are saturated. Cold succeeds, and 
from the expansion produced by frost the bone is shivered 
with an incalculable number of microscopic rents. These in- 
crease until cohesion is overcome and the bone falls apart. 
The mammalian remains may also be placed in soft and 
water-saturated districts, as swamps and estuaries, lake sides 
and spring bottoms, whither animals have been attracted by 
supplies of water or because herbage and prey were equally 
abundant. Bones and osseous remains of vertebrates buried 
in rich carbonaceous soil must, to some extent, yield to the 
corroding action of organic acids. The important roll played 
by organic acids as agents of decomposition has been recog- 
nized.. The numerous orders of oxygenated compounds known 
as acids, and which result from the accumulation of vegetable 
