VEGETATION OF THE COAL PERIOD. 
425 
coal. Seven species of this plant occur in the great Nova 
Scotia section before described, where the stems of some of 
them five inches in diameter, and sometimes eight feet high, 
may be seen terminating downward in a tapering root (see 
Fig. 460). 
Botanists are not yet agreed whether the Asterophyllites^ 
a species of which is represented in the annexed Fig. 461, can 
Fig. 460. Fig. 461. 
Radical termination of a Asterophyllitea foUosm. (Foss. Flo. 25.) 
Calamite. Nova Scotia. Coal-measures, Newcastle. 
form a separate genus from the Calamite, from which, how¬ 
to Dr. Dawson, its foliage is 
ever, accordino: 
Fio-. 462 . ^ mid-rib, which is 
distinguished 
wanting m 
Fig. 463. 
the 
leaves known to belong to some Calamites. 
Figs. 462 and 463 represent leaves of Amm- 
laria and Sphenopliyllum^ com¬ 
mon in the coal, and believed 
by Mr. Carruthers to be leaves 
of Calamites. Dr. Williamson, 
who has carefully studied the 
Calamites, thinks that they 
had a fistular pith, exogenous 
woody stem, and thick smooth 
bark, which last having always 
disappeared, leaves a fiuted stem, as repre¬ 
sented in Fig.-459. 
Sigillaria. —A large portion of the trees of 
the Carboniferous period belonged to this genus, of which as 
many as 28 species are enumerated as British. The structui-e, 
both internal and external, was very peculiar, and, with ref¬ 
erence to existing types, very anomalous. They were for¬ 
merly referred, by M. Ad. Brongniart, to ferns, which they 
resemble in the scalariform texture of their vessels and, in 
Annularia .^pheno- 
phylloides, Daw¬ 
son. 
Splienophyllum ero- 
sum, Dawson. 
