RemarTis on the Natural order Cycadece. 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- 

 spermcE approach closely in their affinities to Flowerless Plants, 

 through the Cycadese, 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 thecae in Os- 

 mundaceae, and the same pinnated foliage and simple columnar trunks 

 as some of the arborescent Ferns. They are also related to Equi- 

 setaceae 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- 

 blance of those 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 

 Cycadeas and Coniferse, 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 Algee, Equisetaceae, and Ly- 

 copodiacese, with Cycadeae, Conifers, 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 reiytiles''— (those strangely formed ani- 

 mals, the aquatic and amphibious Satirians, 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 Equisetaceae of enormous size, herbaceous and ar- 

 borescent Ferns, the latter of extraordinary altitude, and Lycopodi- 

 aceae, 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 Coniferae and Cycadeas, which compose a very con- 

 siderable proportion of the flora 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 fossil woods, have been able to call in the microscope to their aid, and 

 have ascertained their structure in the most satisfactory manner. Their examin- 

 ations have led them to the conclusion, that all known exogenous fossil woods be- 

 long either to ConiferEe or Cycadese. 



