302 CALAMITES. [CH. 



In the following account of the Calamites, the generic 

 name Calamites is used in a wide sense as including stems 

 possessing different types of internal structure; when it is 

 possible to recognise any of these structural types the terms 

 Calamodendron, Arthropitys or Arthrodendron are used as 

 subgenera. The reasons for this nomenclature are discussed in 

 a later part of the Chapter. 



f This term was originally applied 



^ ^- .. oil -ihTi^to the common pith-casts of Cala- 



Genus(7atamife5, Suck ow, 1714 < .^ , ^.^, ^ . 



' mitean stems, without reference to 



^ internal structure. 



Subgenera Calamodendron, Brongniart, 1849 ^ These names 



Arthropitys Goppert, 1864 I have primarily re- 



Arthrodendron Scott 1897 j ference to internal 



{ = Calamopitys Williamson, 1871 )>' structure. 



II. Description of the anatomy of Calamites. 



a. Stems. h. Leaves. c. Roots. d. Cones. 



No fossils are better known to collectors of Coal-Measure 

 plants than the casts and impressions of the numerous species 

 of Calamites. In sandstone quarries of Upper Carboniferous 

 rocks there are frequently found cylindrical or somewhat 

 flattened fossils, varying from one to several inches in diameter, 

 marked on the surface by longitudinal ridges and grooves, 

 and at more or less regular intervals by regular transverse 

 constrictions. Similar specimens are still more abundant as 

 flattened casts in the blocks of shale found on the rubbish 

 heaps of collieries. The sandstone casts are often separated 

 from the surrounding rock by a loose brown or black crumbling 

 material, and the specimens in the shale are frequently covered 

 by a thin layer of coal. 



Most of the earlier writers regarded such specimens as the 

 impressions of the ribbed stems of plants similar to or identical 

 with reeds or grasses. Suckow, and afterwards Dawes and others, 

 expressed the opinion that the ordinary Calamite cast repre- 

 sented a hardened mass of sand or marl, which had filled up the 



