82 THE CANADIAN NATURALIST. [March 



that these plants had a thin internal investment of vascular 

 tissue, having somewhat large vessels with numerous rows of 

 pores, a curious and peculiar form of scalariform tissue which will 

 be found figured in Acadian Geology, page 442, where leaves of 

 Calaiiiites actually found attached to the stems are also figured.* 



The plants above described are the true Calamites, of which 

 several species occur in the Devonian and Carboniferous ; though 

 except when the stems are very well preserved or have the leaves 

 attached, it is difficult to fix the limits of these species ; and it is 

 probable that many have been named which are merely varieties, 

 depending on the age of the stems or their state of preservation. 



But beside these there occur striated and jointed stems of a 

 very difierent character. Their internodes are usually, though 

 not always, short, they have no distinct scars at the nodes, 

 their ribs are usually narrower and more angular ; and when 

 found well preserved, instead of being entire stems, they prove to 

 be casts of an internal cavity surrounded by a thick woody 

 envelope disposed in radiating wedges, and exhibiting not true 

 scalariform tissue, but wood-cells with bordered pores under that 

 transversely elongated variety in which they occur ia the axes 

 of Cycads and the inner layer of the axes of SigUlaria, along with 

 round pores, — also similar to those of Cycads. Stems of this 

 kind have usually been described as Calamites, and many of them 

 have been included under the species C. approximatus, but they 

 are evidently very diflferent from the ordinary Calamites, and of 

 much higher organization, approaching in this respect to Sigillarias. 

 Unfortunately their external surface is not well preserved, but it 

 appears to have been destitute of transverse joints, and to have 

 been irreg-ulurly ribbed, at least near the base of the stem. 

 Bronguiart places them with the Asterophyllites,t and suggests 

 that some of the leaves referred to that genus may have belonged 

 to Calamodendron ; but so far there is no certain evidence of 

 this. Brongniart has on the whole very accurately stated the 

 distinction between the two genera, Calamites and Calamoden- 

 dron, in the work already cited ; as the writer has amply satisfied 

 himself by the study of the beautiful Calamite brakes so well 

 exposed in the cliffs of the South Joggins section, and of several 



* See also paper on Structures in Coal. Journal of Geological Society 

 1860, p. xviii., fig. 11. 



t Tableau des genres, 1849. 



