LEPIDODENDRON. 467 
diaceae, and their size, and abundant occurrence 
among the fossils of the Coal Formation have 
led writers on fossil plants to infer that great 
heat, and moisture, and an insular Position were 
the conditions, under which the first forms of this 
family attained that gigantic stature, which they 
exhibit in deposits of the Transition period ; thus 
corroborating the conclusion they had derived 
from the Calamites associated with them, as 
already mentioned.* 
Lindley and Hutton state, that Lepidodendra 
are, after Calamites, the most abundant class 
of fossils in the Coal formation of the North of 
England ; they are sometimes of enormous size, 
fragments of stems occurring from twenty to forty- 
five feet long ; in the Jarrow colliery a com- 
pressed tree of this class measured four feet two 
inches in breadth. Thirty-four species of Lepi- 
* The leaves of existing Lycopodiacege are simple, and ar- 
ranged in spiral lines around the stem, and impress on its sur- 
face scars of rhomboidal, or lanceolate form, marked with prints 
of the insertions of vessels. In the fossil Lepidodendra, we find 
a large and beautiful variety of similar scars, arranged like scales 
in spiral order, over the entire surface of the stems. A large 
division of these are arborescent and dichotomous, and have their 
branches covered with simple lanceolate leaves. Our figure of 
Lepidodendron Sternbergii (PI. 55. Figs. 1. 2. 3.) represents all 
these characters in a single Tree from the Coal mines of Swina 
in Bohemia. 
The form of the scales varies at different parts of the same 
stem, those nearest the base are elongated in the vertical di- 
rection. 
