i4 STUDIES IN FOSSIL BOTANY 



specimens, and it becomes necessary to make use of 

 other means of discrimination. In the case of the 

 Cryptogams, which play so important a part among 

 plants of the earlier periods, few conclusions can be 

 drawn, even where the fructifications are preserved, 

 without the use of microscopic characters. Still more 

 is this the case when vegetative organs alone are 

 preserved. Among the plants of the more ancient 

 formations, necessarily very remote from any now 

 living, little reliance can be placed on the mere external 

 vegetative characters, while experience has shown that 

 anatomical structure affords a much more trustworthy 

 clue, when interpreted with proper care and judgment. 

 Hence the study of the more minute structure, which 

 is beginning to take a more prominent place, even in 

 recent taxonomy, is relatively of far greater importance 

 when we are dealing with fossil specimens. The most 

 favourable cases for investigation are of course those in 

 which the fructification is itself well preserved, and, 

 fortunately, specimens of this nature are tolerably 

 frequent. 



In selecting examples of fossil plants for our con- 

 sideration, I propose to begin with the Vascular 

 Cryptogams. It is among these plants, together with 

 the Fern -like Spermophyta and the Gymnosperms, 

 that palseobotany has so far made its most important 

 contributions towards the completion of the natural 

 system, and to these Sub -kingdoms our studies will 

 be devoted. As we proceed we shall find that the 

 data afforded by the study of fossil plants demand 

 considerable modification of the current system of 

 classification. 



