ON APHYLLOSTACHYS. 227 
several Orobanches. Soon there developes from this or that point of 
their rhizomatous branches, often 30 feet long, as from a punctum 
vegetationis, a large dome-shaped structure, from which rises the 
genuine trunk, which is 60-80 feet high, cylindrical and densely clad 
with grass-like, narrow leaves, and has verticillate branches. Its' inner 
structure does not at all agree with that of the Lycopodmcece, as might 
be supposed from their fruit agreeing somewhat with that of that family. 
On the contrary, its woody cylinder is furnished with medullary rays and 
radiating scalariform vessels, reminding us of Ferns and Gymuosperms, 
while only the parenchyma of the bark and the vascular bundles 
branching off from it to the leaves show a relationship witli the Igco- 
podiacea. And the Sigillarias occurred in crowded, compact masses, 
like most of the forest-forming trees of the present day, for they 
make up the bulk of the coal, which is found only in any quantity in 
places where the shales and sandstones are full of the remains of this 
genus, and only in small quantities where, as in the Lower Coal and the 
Permian formation, they are rare. We may assert then, with confidence, 
that there never has existed on earth a family possessing so many 
peculiarities, and at the same time having such an extensive range, as 
the Sigillaria ; nor has there ever been any analogous form, with the 
exception of Pleurowoia, of the Bunter Sandstein, a formation which, 
hke those of the Palaeozoic period, docs possess types for which we 
have hitherto sought in vain for analogous forms. 
4. A gradual progression from the lower to the higher types, but 
only in a general way, cannot be denied, but it has only taken place in 
the same class or in the same Order, without affecting the retrograde 
movements which have occurred in certaiu families of the same class 
or Order. 
-thus the vegetation of our globe commenced with Alga, but one 
would make a mistake in supposing that the lowest forms ap- 
peared first and isolated. This is bv no means the case, as I showed 
some years ago in my c Uebergangs-flora,' where I pointed out the co- 
existence of the lowest unicellular Alga, as the Caulerpas and Con- 
fervas, with the higher Florida, and even a Calllthamnion. Some- 
thing similar is observed among fishes, which first appear in the 
-Devonian rocks, not in species belonging to the lowest groups, but 
Wlt h the sharks and ganoids. 
In the Natural System the Fungi are of a lower grade than the 
