428 
PALAEONTOLOGY OF ILLINOIS. 
concretions of Mazon creek, and both present the same appearance. Some 
plants resembling ours have been described under the generic name of Antho- 
lithes. But this genus is still indefinite, and the plants referred to it really 
unknown. I have, therefore, placed this species for description in this new 
genus of Goppert, as more related to it by some of its characters. 
v fin f | • 
Genus Lepidodendron, Sternb. 
Ill. Geol. Report, vol. ii, p. 451. 
The species of this genus, as it is well known, are characterized merely by 
the form of the cicatrices, which have been left by the base of the leaves upon 
the bark of the trees or of their branches. These cicatrices or bolsters vary 
indeed in size and also in their relative position, according to the thickness of 
the different parts of a tree, where they are examined. But this variety is far 
from being as marked as some authors, who have attempted to reduce the spe¬ 
cies to two or three, seem to suppose it. In following the course of the devel¬ 
opment of these scars on long stems of Lepidoclendrun, from parts measuring at 
least one foot in diameter to the smallest branches, they may be seen to vary 
in size and position according to the degree of activity of the vegetation at 
different times, and also on account of some irregular mode of growth; but 
their essential characters, viz.: their outline, the position of the vascular 
points, as also the form of the leaf scars surrounding them, is generally pre¬ 
served and recognizable in the whole length of the stem. It is argued that 
for the genus Lepidodendron, we should have too large a number of species if 
we would consider the scars as specific characters. But the genus Sigillaria, 
so admirably studied by Prof. Brongniart, and after him by the most careful 
Palaeontologists, especially by Goldenberg, whose acuteness of observation is 
beyond question, has a number of acknowledged species, at least double of those 
of the genus Lepidodendron. Goldenberg describes sixty-seven species of 
Sigillaria ! and yet the specific characters are taken from the same vegetable 
organs, or from the cicatrices of the bark, which are certainly as much subject 
to variations in Sigillaria as in Lepidodendron. Why, then, deny the value of 
the species of one genus, and admit the reality of those of the other. The 
most marked species of Lepidodendron of our American coal fields, L. modula- 
tum, L. giganteum, L. clypeatum, L. vestitum, L. distans, published in the Geo¬ 
logical Report of Penna., have been found over the whole extent of our Coal 
Measures, and are recognized everywhere by their distinct characters from the 
form of their cicatrices. In collecting specimens on shale, for the State Cabi¬ 
net, great care has been taken in comparing the largest possible number of spe¬ 
cimens of the same species at the same place, not only to obtain the different 
