X] 



CALAMITES AND EQUISETUM. 



381 



Subgenera having 

 reference to the method 

 of branching as seen in 

 casts or impressions of 

 the stem-surface or in 

 pith-casts. 



Calamitina, 



Eucalamites, 



Stylocalamites. 



CALAMITES. 



Subgenera founded 

 on anatomical charac- 

 ters in stems and 

 branches. 

 Arthropitys, 

 Calamodendron, 

 Arthrodendron (new 

 sub-genus substi- 

 tuted for Calamo- 

 pytus). 



Genus proposed for 

 roots of Calamites be- 

 fore their real nature 

 was recognised. The 

 name refers to anato- 

 mical characters. 

 Astromyelon. 



Genera of which 

 some species, if not 

 all, are the leaf-bearing 

 branches of Calamites. 

 CaZamocladus (in- 

 cluding Astei'o- 

 phyllites), 

 Annularia. 



Generic names ap- 

 plied to strobili belong- 

 ing to Calamites. 



Calamostachys., 

 Palaeostachya, 

 Macrostachya^ 

 etc. 



Genus includinf 

 impressions of Gala 

 mite roots. 



Pinnidaria. 



IV. Conclusion. 



A brief sketch of the main features of Calamites suffices to 

 bring out the many points of agreement between the arborescent 

 Calamite plants and the recent Equisetums. The slight vari- 

 ation in morphological character among the present-day Horee- 

 tails, contrasts with the greater range as regards structural 

 features among the types included in Calamites. The Horse- 

 tails probably represent one of several lines of development 

 which tend to converge in the Palaeozoic period ; the Calamite 

 itself would appear to mark the culminating point of a certain 

 phylum of which we have one degenerate but closely allied 

 descendant in the genus Equisetum. We shall, however, be in 

 a better position to consider the general question of plant- 

 evolution after we have made ourselves familiar with other 

 types of Palaeozoic plants. Grand'Eury's* striking descriptions 



1 Grand'Eury (77), (90). 



