KIIXSTON': THE FLORA OF THE CARBONIFEROUS PERIOD. 201 



of stem. The aerial stems of Calamites spring from creeping 

 rhizomes as seen in the figure of Calamites Suckoivii, given on 

 Plate XXX., fig. 1, as well as from the subterranean portion 

 of the aerial stems (Plate XXXV., fig. 3). 



Let us now return to the consideration of the three groups 

 of stems, to which reference has just been made : — 



I. — Calamitina. 



Calamites varians Sternb. may be taken as t3'pical of this 

 group (Plate XXXIV., fig. 1. Calamitina varians var. inconstans 

 Weiss). 



The internodes vary in length, and the nodes bear closely- 

 placed transversely oval leaf scars. The bark is smooth but 

 frequently shows slight longitudinal clefts or cracks, which vary 

 in their length and distance apart. These longitudinal cracks 

 or lines probably arise through the splitting of the bark from 

 the increase of the stem in girth. Between each branch-bearing 

 node several bi'anchless nodes intervene, their number varying, 

 not only in the same species, but even on the same specimen. 

 The foliage of some Calamitince consisted of acicular leaves, but 

 whether all possessed such foliage is not known (Plate XXXVI. , 

 fig. 1). 



II. EUCALAMITES. 



Calamites ramosus Artis. is representative of this section 

 (Plate XXXVII., figs. 3 and 4). Each node gives rise to two 

 branches, one on each side of the stem. The branches are super- 

 posed, and, though these again bear lateral branches, the plant 

 would possess the form of a triangle. The surface of the 

 stem is smooth. Plate XXXVII., fig. 4, shows the cast of the 

 pith cavity ; fig. 3 shows the outer surface of the species with 

 smooth bark. 



The foliage of Calam,ites raviosus consisted of lanceolate leaves, 

 arranged in whorls and united by their bases to form a very narrow 

 ring round the stem. This foliage was named Annularia radiata 

 by Brongniart before it was discovered to be the foliage of 

 Calamites ramosus (Plate XXXVII., fig. 1). 



