LIXNBAK SOCIETY OF LOXDO:^. 29 



and for manj^ decades afterwards, there was no suspicion of the 

 kind. Hooker, in fact, speaks of the ferns as the onl}' group with 

 obvious or recognisable affinities with an existing order. He even 

 regarded Pecopteris as " the fossil representative, if not congener, 

 of the modern Pteris" (p. 401); adding that it is not improbable 

 that there are other genera of living ferns fossilized in the shales 

 of the coal-formation. He illustrates the heteromorphous frond of 

 his Pecopteris heteropJu/lla (now AJetliopteris decurrens) by that of 

 the New Zealand Pteris esculenta (figs. 1 & 2), an analogy none the 

 less striking because the plants have proved to be really so wide 

 apart. It is interesting, however, to note that he already recog- 

 nised the affinity of Corda's Smftenuergla, of which the fructification 

 was known, with a recent group of ferns [Aneimidicti/oii, our 

 Aneimia), a view now generally admitted. 



Discussing the bearing of the supposed predominance of ferns 

 on the question of climate he writes: "A climate warmer than 

 ours now is would probably be indicated by the presence of an 

 increased number of flowering plants, which would doubtless 

 have been fossilized with the ferns ; whilst a lower temperature, 

 equal to the mean of the seasons now prevailing, would assimilate 

 our climate to that of such cooler countries as are characterized 

 by a disproportionate amount of ferns" (p. 404). Thus he 

 appears to explain the absence of flowering plants from the Coal- 

 flora by the climatic conditions. 



Hooker, at that time, was quite alive to the remarkable rarity 

 of fructifications on the fossil ferns of the Coal, and cites a 

 striking analogy in explanation. " The infrequency of fructifica- 

 tion upon the fronds of the fossil ferns belonging to this 

 formation appears as possibly another argument in favour of 

 many of those appertaining to tree-ferns ; for, while the her- 

 baceous and caulescent ferns of New Zealand are scarcely ever 

 barren, the arborescent species are almost invariably so. I think 

 I am safe in saying that of two or three kinds of New Zealand 

 tree-fern, not one specimen in a thousand bears a single fertile 

 frond, though all abound in barren ones " (p. 405). This observa- 

 tion must still have considerable weight when we are tempted 

 to rely on ner/ative evidence in judging of the nature of Carbon- 

 iferous fern-like plants. 



Hooker gives some striking examples of the worthlessness of 

 external vegetative characters in ferns, showing how one and 

 the same frond might, in the sterile condition, be equally well 

 referred to four different genera (p. 408). Attention is also 

 called to the dimorphism, in many cases, of the fertile and sterile 

 fronds, a point of much importance, as it has proved, in dealing 

 with the so-called ferns of the Carboniferous. 



Venation, a character much relied on by pteridologists from 

 Brongniart onwards, is shown to be usually characteristic of minor 

 divisions, though not always valid even for them, while useless 

 for the discrimination of main groups. Hence genera founded 

 on venation must be wholly artificial. Although no pala)obotanist 



