MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
59 
filaments or laciniae which traverse the interior of some of the 
more fleshy algae. 
However, the fibrous structures traversing the interior of algae 
possess such a small quantity of carbon that it is difficult to 
conceive how they could remain in a fossil form as anything but 
the thinnest imaginable traces. In Leveilleites, on the contrary, 
they appear like fibers which had not given way to pressure. 
In fact, they appear more like fibers of sponges than of fibers 
which could have originated from algae. 
Moreover, in the frondose fleshy algae it seemed reasonable 
to expect occasional traces of organs of reproduction, in the 
form of swellings of the fronds or other structures of sufficient 
size to warrant their recognition even in fossil form, but nothing 
of the kind was discovered among the numerous specimens 
examined. 
In fact, as more material accumulated, the plant origin of 
these frondose organisms found at Credit Forks seemed less 
certain, and the possibility of their being of animal origin less 
doubtful. 
The reference, in preceding lines, to fibers of sponges is not 
intended to suggest that Leveilleites may be some early type of 
sponge. It is possible that some other form of animal life 
with more or less fibrous material within its structure, not yet 
clearly recognized, may have existed in Ordovician and Silurian 
times. 
Since these frondose organisms found at Credit Forks present 
more structure than any similar fiat plant-like bodies found here- 
to-fore, they are described and figured in much greater detail 
than otherwise would prove desirable. In the twelve years 
which have elapsed since their discovery, no additional informa- 
tion has been added as the result of further study either of old 
material, or material accumulated more recentl}^. Therefore, 
it does not seem advisable to withhold the publication of these 
observations any longer. 
To the account of Leveilleites is added a description of Dictyo- 
nema scalarif orme creditensis, Foerste found in the same slabs 
of rock as Leveilleites. Several species of fossils found in the 
