PALEONTOLOGY: C. A. DAVIS 
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pattern formed by small crowded hexagonal depressions on the surface 
of the film. The meaning of these netted areas has not yet been worked 
out, but it seems possible that the structure is a reproductive surface 
from which spores arise. The whole plant after most careful exami- 
nation seems to have been made up of gelatinous material forming a 
thallus, with no definite divisions into cells. 
Besides the filmy gelatinous types, there are large numbers of seemingly 
gelatinous forms that were more or less filamentous. These types vary 
greatly in the length and width of their filaments, which are often more 
or less flattened, and which branch in an eccentric way, quite unusual 
among the modern Algae. The filaments lack visible divisions into 
definite cells and seem to have been wholly gelatinous or to have been 
sheathed by thick gelatinous envelopes, which have obHterated the 
evidences of cell division. 
It is well known, however, that we have very slight and indefinite 
knowledge of the floras of present-day fresh and salt waters, especially 
of those which grow in and around the deeper parts of waters in which 
there are deposits of organic origin, and many of the plants which have 
been described from shallow waters are so imperfectly known that their 
life histories have never been worked out. These facts make the study 
and classification of fossil forms much more difiicult than it would other- 
wise be, and their relationships harder to determine. 
Careful study of the material under discussion indicates how perfectly 
plant remains, originally of the most delicate structure, have been pre- 
served. Even very thin-walled and fragile cells and filaments show by 
internal evidence that they did not even collapse as they were incor- 
porated into the mass in which they are preserved. Contraction, caused 
by shrinkage from the loss of water in the original substances, and the 
later changes which have transformed them into rock, has manifestly 
occurred. Dehydration has been so slow and regular, however, that it 
has produced no changes that have in any way interfered with the micro- 
scopic study of the properly prepared material. The perfection of the 
preservation of the plant remains in these rocks is such that it is quite 
evident that, with such specimens to work with, there need be no difii- 
culty in learning the facts or in fully and correctly interpreting them. 
All doubt as to the possibility of Algae, and similar cellular plants of 
most delicate structure being preserved and their remains becoming a 
conspicuous part of the organic matter found in carbonaceous rocks is 
removed by the studies here recorded. 
The discovery of this interesting flora of minute fossil Algae, doubtless 
the most extensive of its class yet reported, embracing as it does thou- 
