PALEONTOLOGY: C A. DAVIS 
115 
Formation of Eocene time. This formation is widely known in some of 
its Wyoming phases for its richness in fossil fish remains. 
About a year ago, samples of the shale from near De Beque, Colorado, 
and, later, from other localities, were submitted to me for microscopic 
examination. Inspection led to the conclusion that the rock was com- 
posed so largely of organic residues, that it would be practicable to apply 
to it methods of sectioning already in use for making thin sections for 
the microscopic study of peats and coals. 
After some experimental work, it was found possible so to soften the 
material without any visible change in its original form or structure, 
that after it was imbedded in parafhn, sections could be made from it 
with razor or microtome as readily as from properly prepared fresh 
vegetable tissue. Sections of any desired thinness can thus be made, 
and in any quantity. Moreover, these sections can be so treated that 
when mounted they can be studied with the highest powers of the com- 
pound microscope. 
Several highly interesting and important facts have been discovered 
by examining specimens of the shale prepared as outlined above. The 
ground mass of the sections was found to be of the nature of a somewhat 
granular, organic jelly, closely resembling in optical properties, some of 
the structureless, colloidal or sapropelic peats, solidified and compacted 
into a dense, tough, impermeable magma. 
Apparently the hardening and compacting of this material from its 
original gelatinous condition to its present state, was a process of slow 
dehydration and contraction, without any violent disturbance or action 
of any outside metamorphosing agencies. This is shown by the undis- 
turbed position and structure of the shale beds in the mass, as well as 
by the almost entire lack of visible changes in the delicate plant struc- 
tures that are often abundant in the sections examined. 
The ground mass, magma, or body of the shales, from its structure 
as seen under the microscope, seems to have been originally vegetable 
matter. It apparently was a mixture of finely divided and flocculent 
plant debris and living microscopic plants, bacteria, etc., most of which 
probably were more or less saprophytic, decomposing and still farther 
disintegrating the mass of detritus in and on which they lived. 
Imbedded in this magma, as many of the sections showed, are in- 
numerable plant cells, structures, and entire plants, almost as perfectly 
preserved as if they had been prepared by the most refined methods of 
the plant morphologist. Many of these fossils are spores, fungi or 
structures belonging to the higher plants, but a large percentage of them 
are clearly Algae of low types. Three distinct types of Algae have been 
discovered by the work so far done. 
