FILICIN®. 37 
geological horizon. The termination “tes,” or some similar 
widely adopted ending, is in some degree a safeguard; it at least 
shows at once that the species is a fossil, and not a recent fern, 
and, therefore, as experience has taught, to be accepted cautiously. 
To retain all the old names in spite of advance in scientific 
knowledge would be at once a want of recognition of palzeobotanical 
progress, and a serious obstacle to phylogenetic investigations. 
The better plan, and one less likely to add unsound links in the 
chain of evidence on which genealogical diagrams are attempted, 
would be to retain the older system of nomenclature, proposed by 
Brongniart and added to or modified by subsequent writers, until 
such specimens are forthcoming which supply us with fertile fronds 
or pinne, and thus render possible a comparison with recent forms 
based on a surer foundation. 
In Hooker’s well-known paper ‘On the Vegetation of the 
Carboniferous Period, as compared with that of the present day,’’! 
the difficulties of determining fossil ferns are brought home in a 
clear and striking manner by one well qualified to speak on the 
characters of recent ferns. Many of these difficulties are recognized 
by all who have even the most superficial acquaintance with 
palzobotanical herbaria, but it is probable that had more attention 
been paid to Hooker’s valuable cautions our lists of synonyms 
would not have reached that length and variety which they too 
frequently show. 
There are a number of fossil ferns from rocks of different ages, 
named neither on account of their venation nor fructification 
characters, but on certain morphological characteristics which are 
easily recognized and typical of some peculiar modern genera. 
No doubt such a basis for a generic title may often be trustworthy, 
and exceedingly useful as a means of arriving within measurable 
distance of natural affinity. In such cases, therefore, where we 
have striking morphological features to guide us, we may with 
advantage make use of them without waiting for the further 
evidence of sori or sporangia. 
In the works of Stur? and Zeiller* on Carboniferous ferns we 
have admirable proofs of the better material which paleobotanists 
1 Mem. Geol. Surv. vol. ii. pt. ii. 1848. 
2 Loe. cit. 
3 Bassin Houiller de Valenciennes. 
