THE CARBONIFEROUS AND PERMIAN FLORAS. 487 



large number of characteristic Carboniferous species. In 

 Odontopteris (fig. 385) the frond is pinnate, the leaflets being 

 attached by their entire bases, and the veins are generally 

 given off from the base. The species here figured is a widely- 

 distributed one, occurring in both Europe and North America. 



Fig- 385. Odontopteris Schlotheimii. Carboniferous of Europe and North America. 



In the genus Sphenopteris, the leaflets are narrow towards their 

 bases, often assuming a wedge-like form, the nervures dividing 

 in a pinnate manner from the base. 



Lastly, in the genus Hymenophyllites the frond exhibits a 

 general resemblance to Sphenopteris, but the margin is divided 

 into lobes, into each of which a single nervure is continued. 



b. Catamites. Amongst the commonest and most charac- 

 teristic of the plants of the Carboniferous period are the 

 striated fossils which are known as Calamites. Long as these 

 have been known, and carefully as they have been studied, 

 there is still no unanimity of opinion as to the affinities of 

 these plants. The prevalent modern view, however, is that 

 Calamites are truly referable to the Equisetacea, and that they 

 may be regarded as gigantic Horse-tails though they differ 

 in many respects from any existing forms. The Calamites 

 were " slender, ribbed, and jointed externally, and from the 

 joints there proceeded, in some of the species, long, narrow, 

 simple branchlets ; and, in others, branches bearing whorls of 

 small branchlets or rudimentary leaves. The stem was hollow, 

 with thin transverse floors or diaphragms at the joints, and it 



