Remarks on the Natural order Cycadea. 51 
Placed thus as it were at the lowest step in the gradation of plants 
which have a vascular system and an exogenous structure, Gymno- 
sperme approach closely in their affinities to Flowerless Plants, 
through the Cycadee, which have mostly the same gyrate verna- 
tion as the Ferns, a manner of producing their seeds upon the mar- 
gins of the leaves, analogous to the production of the thece in Os- 
mundacez, and the same pinnated foliage and simple columnar trunks 
as some of the arborescent Ferns. ‘They are also related to Equi- 
setacee by a similar simplicity of structure in the female organs, if 
the sporules of that singular order are really naked ovula, as is very 
plausibly suggested by M. Ad. Brongniart. At least the resem- 
ose organs to the female flower of Zamia, is in the high- 
est degree obvious and striking. 
But the relation between the Ferns and other flowerless plants, and 
Cycadee and Conifere, as well as the importance of these orders 
in former times, can only be properly appreciated by those who have 
paid attention to fossil botany, and are acquainted, by means of that 
interesting science, with the primitive flora of the globe. In those 
remote ages, when Ferns and marine Alge, Equisetacew, and Ly- 
copodiacez, with Cycadex, Conifere, and a few Palms, constitu- 
ted the whole of the vegetable kingdom, these orders occupied a 
much more conspicuous station than at the present day. At that 
period, when, as geology has now incontestibly proved, the globe 
was tenanted by a “race of reptiles’ ’—(those strangely formed ani- 
mals, the aquatic and amphibious Saurians, which existed before 
the formation of the secondary strata,)—the vegetation of the earth 
was also in a corresponding primitive state of organization. Cellu- 
lares or flowerless plants, covered the greater portion of the globe ; 
_ among which were Equisetacee of enormous size, herbaceous and ar- 
borescent Ferns, the Jatter of extraordinary altitude, and Lycopodi- 
acee, an order now dwindled down to a few diminutive, moss-like 
plants, but which, it is thought by Brongniart, reached at that time 
the stature of our tallest forest trees. Associated with these, are 
found the first Conifere and Cycadew, which compose a very cou- 
siderable proportion of the fora of those remote ages, being proba- 
bly the next advance in the ascending scale of vegetable structure. 
sands of years! Messrs. Nicol and Witham, by grinding down to very thin plates 
sections of fond) woods, have been ae to call in the microscope to their aid, and 
t satisfactory manner. Their examin- 
ations h: ave led them to the att that all known exogenous fossil woods be- 
long either to Conifere or Cyca 
