AS COMPARED WITH THAT OF THE PRESENT DAY. 403 



many of the genera put into the order (as Asterophyllites* Spheno- 

 phyllum, &c.) really belong to it or not, until some evidences be gained 

 from their fructification. 



This absence of fructification not only prevents our defining the 

 limits of the fossil ferns as an order, but deprives the botanist of one of 

 the most important generic characters that the plants comprised in 

 it afford. As will be hereafter shown, it is generally impossible to trace 

 the affinities of a fern without the fruit, and often even to refer it to the 

 section or subdivision in which it should be placed. 



There are two other points which cannot fail to strike the observer of 

 fossil ferns : they are, the absence of a singular aspect of fronds in a 

 state of incipient vernation, that is curled up like a crozier, as the 

 fronds of all are in a young state. In the perennial existing species, 

 fronds in this state may be seen on the plants at all seasons, and even in 

 the annuals they are visible for many months ; so that it were diffi- 

 cult to select a season of the year during which a modern fern Flora 

 could be fossilized without very many such fronds being preserved, as 

 well as fully expanded ones ; but in the coal formation these are exces- 

 sively rare. That they do occur is evidence that the evolution of the 

 leaves followed the same law then as now ; while this extreme infrequency 

 would seem to indicate, either that the majority of the species were 

 annual, and fossilized at an advanced season of the year, possibly coin- 

 ciding with a sudden depression of the surface ; or that they were 

 perennial, and the old fronds dropping from time to time off the parent 

 trunk, were subsequently fossilized. 



Again, the almost universal absence of any defined termination 

 to the stalks (stipites) of the fronds, or of any such masses of woody 

 roots or rhizomata as those of modern ferns, is highly remarkable. t 

 In the case of recent species we find long and strong under-ground 

 woody roots, or more frequently great knotty masses above the surface 

 of the earth, from out of which the fronds spring. But in the case of 

 fossil ferns, there is hardly such a thing known as a specimen presenting 

 two fronds attached to one stem. This may readily be explained on 

 the supposition that the ferns are all fragments, transported to the 

 position they now occupy, an hypothesis gravely objected to by many 

 close observers on geological grounds. Another suggestion which 

 offers itself is that the fronds are the deciduous ones of tree-ferns ; this 

 is much more plausible, though almost necessarily involving the con- 



* My friend, Mr. Bunbury, informs me that he is possessed of American specimens of 

 this genus with the organs of fructification preserved. 



f Several authors have figured small ferns, in which both the fronds, their axis of sup- 

 port, and root, are well preserved ; but the species are very scarce, much smaller, and 

 of a different character to the prevailing forms of the coal formation. 



II. 2 F 



