305 
than he whose investigations embrace the higher forms of 
organised beings. The difference arising not only from 
the tissues of plants being less enduring, and their several 
portions or organs more disjointed and separated, but 
also from the majority of them belonging to genera either 
extinct or whose true analogues are doubtful at the present 
day. For instance, if we take such genera as Sigillaria, 
Halonia, Bothrodendron, Ulodendron, Megaphyton, Stern- 
bergia, and Calamites, their true position is unknown. The 
terminal extremities and the roots have been found in only 
one of these genera, that of Calamites ; and the roots and 
stems only of another, Sigillaria. What do we know of the 
foliage of any of the above genera ? Actually nothing with 
certainty ! Fronds and stems are frequently found associated 
in the same matrix, but never united ; and though portions of 
large fronds of Pecopteris, Neuropteris, and similar ferns 
occur in abundance, we do not observe any stems of sufficient 
size to have elevated them, unless some of the former genera 
have been the supporting media, which is very doubtful. 
My friend, E. W. Binney, Esq., of Manchester, who has 
worked with great zeal in the Lancashire coal field, was 
the first, I believe, satisfactorily to demonstrate that Stig- 
maria is the radicular portion of Sigillaria, with numerous 
stringy fibrils, or rootlets, radiating from its surface, which 
was a most important and interesting discovery. But 
allowing that he has been fully justified in his conclusions 
by the examination of numerous specimens, there yet appears 
an anomaly in the root of this plant difficult to reconcile, as 
it is without an analogue in the vegetable kingdom. I allude 
to the quincuncial scars on the surface of Stigmaria, with 
their nipple- shaped centres, which appear to have afforded 
articulating media by which the flat, leaf-like fibrils 
have been attached to the caudex. Now, in the first place 
the regularity of origin in these appendages, if really fibrils, 
y2 
