THE PRIMITIVE VEGETATION OF THE EARTH. 419 
Which, though provisionally placed here, has been variously 
conjectured to resemble Ferns, Cycads, Alge and Grapto- 
lites. But the most remarkable Lycopodiaceous plants are 
the gigantic arboreal Lepidodendra, plants which, while they 
begin in the Middle Devonian, become eminently expanded 
in numbers and magnitude in the Carboniferous. The com- 
mon species in Eastern America (ZL. Gaspianum) was of 
slender and delicate form, very elegant, but probably not of 
large size. In the same family I would place my new genus 
Leptophleum. 
he Calamites, afterwards so largely developed in the 
Carboniferous, and to be replaced by true Equiseta in the 
Trias, make their first appearance in a large species ( C. in- 
ornatum) in the Lower Devonian, and represented in the 
middle and upper parts of the system by two other species, 
which extend upward into the Carboniferous. They are 
also represented in the Devonian of Germany. and of Devon- 
shire. The peculiar type indicated by the internal casts 
known as Calamodendron is likewise found in the Devo- 
nian. 
More beautiful plants were the Asterophyllites, with more 
slender and widely branching stems, and broader leaves 
borne in whorls upon their branches. These plants have 
been confounded with leaves of Calamites, from which, how- 
ever, they differ in form and nervation, and in the want of 
the oblique interrupted lines common to the true leaves of 
Calamites and to the branchlets of Equisetum. The Aster- 
ophyllites, and with them a species of Sphenophyllum, ap- 
pear in the Middle Devonian. 
No plants of the modern world are more beautiful in point 
of foliage than the Ferns, and of these a great number of 
Species occur in the Middle and Upper Devonian. I must 
refer for details to my more full memoirs on the subject, and 
in the present paper shall content myself with a few general 
Statements. Some of the generie forms of the Devonian, 
and perhaps a few of the species, extend into the Carboni- 
