738 FOSSIL PLANTS OF THE CAEBONIFEKOUS SYSTEM. 



that in both Equisetums and Calamites the fibro-vascular bundles are 

 but poorly developed : that the mass of tissue (woody wedges'" of 

 WUliamson) forming the most important part of the stem consists of 

 the small fibro-vascular bundles, with the addition of a large quantity 

 of thickened parenchyma and prosenchyma (sclerenchyma of Met- 

 tenius) : that the sclerenchyma is part of the cortical tissues, and 

 not a portion of the fibro-vascular bundles : that there is no evidence 

 of any growth having taken place in the fibro-vascular bundles com- 

 parable to that observed in Dicotyledons ; but that if the stems of 

 Calamites increased in diameter it was by additions to the cortical 

 tissues, and not to those of the fibro-vascular bundles : that the 

 pointed ends of the Calamite stem (indicating that the embryonic 

 parts did not enlarge) lead to the conclusion that circumferential 

 growth did not take place, but that the stem, when it attained its 

 maximum diameter close to the base, remained cylindrical. 



Fig. 918. 



Kg. 919. 



In Spitzbergen, in rocks of the Carboniferous epoch, there have 

 been found Calamites radiatus, Lepidodendron Veltheimianum, Sigil- 

 laria distans, Stigmaria ficoides, and ferns apparently the same as 

 those found in the Carboniferous epoch in Europe. Some species, as 

 SigiUaria Malmgreni, S. Canneggianna, and Lepidodendron Wilkii, 

 seem to be peculiar to Bear Island. 



In the family Calamitacese we have the genera Equisetites and 

 Calamites. Some also place in this family the genera Asterophyllites, 

 Sphenophyllum (fig. 918), Annularia (fig. 919), and Volkmannia. 

 Annularia may be a link between Equisetacese and Ferns, and Sphe- 

 nophyllum a link between Lycopodiacese and Ferns. Williamson 



Fig. 918.' Sphenophyllum dentatum, one of the dubious forme of the Carboniferous 

 system, perhaps aUied to Balisburya Fig. 919. Annularia brevifolia, a coal plant of 



doubtfni affinity, placed by some among the Calamitacese. 



