VII. 

 FILICES. 



THE Ferns are known to belong to some of the oldest living vegetable 

 types. So far as it is possible to judge of the character of the general 

 vegetation at any given time from the remains preserved to us in the fossil 

 state, we see them continually increasing in the number of individuals and 

 species from the most recent formations backwards to the Carboniferous 

 period. The Devonian beds also are rich in beautiful and well-characterised 

 Ferns. On the other hand, there seems to be no satisfactory example of 

 this group of plants from Silurian deposits, for Eopteris Morieri de- 

 scribed by Saporta 1 from the Middle Silurian roofing-slates of Angers, of 

 which I have seen fine specimens in the collection of the Royal Bergaka- 

 demie at Berlin, is certainly of inorganic origin, being formed of dendritic 

 deposits of iron pyrites. The midrib of the apparent Fern-leaf is the 

 infiltration-canal ; the pinnulae, which are very dissimilar in size and form, 

 show crystalline structure, and this was mistaken for the nervation of the 

 leaf. 



The stems, leaf-stalks and leaves of Ferns are almost always found 

 separate from one another and in a more or less fragmentary condition, and 

 this is especially the case with the many known large and copiously 

 branched leaf-forms, of which we only now and then see fine entire 

 specimens. Isolated pinnules are all that occur of some forms ; it may be 

 concluded from this that they separated regularly from their axes, re- 

 sembling in this respect many of our living Ferns, Marattia, for example, 

 Didymochlaena, Nephrolepis and others. It is wonderful to find in the 

 clay-slates of the Coal-formation such numbers of impressions of quite 

 young leaves in the bud-state. These are recorded in palaeontological 

 works under the generic name of Spiropteris. Leaf-stalks and fragments of 

 leaf-stalks also are constantly occurring, more particularly and in unusual 

 abundance in the Coal-measures, and they are readily recognised on refuse- 

 heaps in coal-mines by their glistening black surface which is rough with 

 small irregularly disposed hairs. In this condition they are, botanically 



de Saporta (10), t. I. 

 K 2 



