118 
PALEONTOLOGY: C. A. DAVIS 
sands of individuals and an undetermined number of species, many of 
which have not yet even been photographed, is in itself a noteworthy 
matter. The discovery seemingly has a more important bearing, how- 
ever, on the broad geologic problem of the origin and development of 
petroleum and related carbonaceous compounds, than it has on that 
of the development of plant life. 
Several steps looking towards the solution of this great genetic problem 
have been taken already and tentative advances have been made. The 
structure of the rock, the kind of fossils in it, and their state of pres- 
ervation, make it possible to determine, to some extent at least, the 
sources of the abundant carbonaceous matter which it contains, and the 
conditions under which this matter accumulated. The state of de- 
composition of the original organic substance contained in the magma 
has, to some extent, to be assumed, since it is so largely structureless. 
It is practically certain from studies made on peat, that the breaking 
down of the original structure of this material is rather a physical than 
a chemical change, a comminution, not a decomposition. The true 
chemical condition of the organic matter of the rock is more correctly 
interpreted from the fossils, which probably are approximately at the 
same stage of carbonization as the structureless magma. The chemical 
condition of the finely preserved fossils, therefore, becomes highly signi- 
ficant, this, judging from their color, physical condition, etc., is indic- 
ative of very early stages of carbonization, which in turn, shows a very 
limited action by the transforming agencies originating within the earth 
itself, i.e., those producing metamorphism. 
Finally, and of great importance in the consideration of the larger 
problem, is the determination of the actual substances now existing in 
the rock itself, from which the distillates obtained by heating, are de- 
rived. It will readily be seen that this constitutes a somewhat pro- 
longed investigation but it is easily within the reach of modern chemical 
science. 
It can already be stated positively that the organic matter of these 
shales, so far as examined, in very large part is of vegetable origin, 
with but very slight traces of the remains of animal organisms. The 
plant remains were accumulated in water of considerable depth and 
purity and in places apparently remote from shore lines. To a con- 
siderable extent this vegetable matter seems to have been of the nature 
of drift material or plankton, although it is largely mixed with the re- 
mains of Algae and similar plants that certainly grew upon and in the 
magmatic mass as a place of attachment, if not actually aiding in its 
decomposition by their growth. 
