

190 kidston: the flora of the carboniferous period. 



and full maimer which one demands in the case of genera 

 founded on existing species. Notwithstanding the difficulties of 

 the subject, by careful collecting and study much has been done 

 in elucidating the structure and form of Carboniferous plants, 

 and in some rare cases our knowledge is little less perfect than 

 if we had been able to study the growing plant. Such results 

 have only been attained by much study and careful observa- 

 tion, and are generally the result of the united labours of 

 sevei-al workers — one laying the foundation and another building 

 thereon. Thus the science of palaeozoic botany has grown and, 



I doubt not, wall grow. 



I. — Ferns. 



If we only consider the mere form of the frond and the 

 arrangement of the veins, many fossil ferns have a considerable 

 superficial resemblance to certain recent species ; still this resem- 

 blance must not be regarded as affording any evidence on which 

 to presume a generic relationship. The fact, however, remains 

 that the same type of pinnule form and nervation which is 

 found amongst Carboniferous ferns is seen amongst those exist- 

 ing at present, and also the same mode of circinate vernation 

 (Plate XXVI., fig. 1). 



In Carboniferous ferns the main rachis sometimes divided 

 into two arms, as in C alymmatotheca bifida L. k, H. sp. (Plate 

 XXV., figs. 2, 3), and this dichotomous division even more 

 frequently occurs in the pinnse, which are once forked, or end 

 in a pair of forks. 



This character is rare in recent ferns in their native 

 condition, but fretjuent in cultivated forms, resulting in the 

 dichotomous or crested varieties of garden origin. 



Among Carboniferous ferns the principal families are the 

 Sphenopteridece., JVeuropteridece, and Pecopteridece. These will be 

 briefly described. 

 Sphenopteride-e. 



Considerable latitude of character is shown by the ferns 

 included in this family. The pinnules may be more or less 

 oval, entire or lobed, and contracted at the base into a short 



