164 
SEAL : FOSSIL PLANTS. 
think, more perfect and beautiful than those in the coal 
measures. 
Specimens of Stigmaria ficoides, deriving its name from 
the stigmata or punctures which ornament its surface, are 
also common. This genus is found in the same deposits, but 
generally slightly lower down. The Stigmaria is now under- 
stood to be the root of Sigillaria, Lepidodendron, &c, and 
usually occurs as an underground stem in the shale or ancient 
mud in which it grew. It is more or less round, sometimes 
compressed, studded with circular pittings arranged in spiral 
order round its surface. Sir Wm. Logan was the first to 
point out that every bed of coal rests on a peculiar clay, con- 
taining vegetable fossils known as Stigmaria, which pierce it 
in every direction, suggesting the idea of their being roots. 
Mr. Binney concurred in this view. If this theory be correct, 
it is somewhat remarkable to find such specimens as these in 
the sandstone rocks, which were probably formed thousands 
of years subsequently to the vast vegetable deposits which 
have resulted in our coal beds. 
I now notice the Lepidodendron Sternbergii. I think its 
nearest living representative is the club -moss commonly 
called Stag's Horn : it differs from the other specimens by 
the scaly appearance of its bark. It is mostly found in 
deeper deposits than the specimens previously mentioned, 
generally about forty feet from the surface. It is most com- 
mon in the strata overlying the best beds of white sandstone 
rock ; and sometimes, to our disappointment and loss, we find 
it running completely through our best beds of stone. 
A comparatively rare genus of fossil plants named 
Halonia is occasionally found. It somewhat resembles 
Sigillaria. I find the markings as follows : protuberances, 
or nodules, which are twisted or contorted and not very 
regularly placed, with slight or faint Lepidodendroid markings 
between and surrounding the protuberances. 
