FLORA OF THE CARBONIFEROUS EPOCH. 



47 



Sigillaria elegans, as figured hj Brongniart in Archives du 

 Museum, i. 405, has a stem consisting of a central cellular axis 

 or medulla, surrounded by a vascular cylinder, and this is in- 

 vested by a thick cellular cortical layer, the outer portion com- 

 posed of fusifonii cells of less diameter than those of the inner 

 portion. What Brongniart calls medullary rays are mere cracks 

 or separations in the wedges traversed by vessels. In its 

 structure it resembles its root Stigmaria, and must be referred 

 to Lycopodiacea3, along with Lepidodendron, Halonia, Ulo- 

 dendron, etc. The small round sporangia of Sigillaria are 



Fi?. 38. 



Fiff. 39. 



borne in a single patch on the somewhat enlarged bases of 

 some of the leaves. (See Carruthers on Structure and Affini- 

 ties of Sigillaria, in Journ. Geol. Soc. Aug. 1869.) 



It has been ascertained by Professor King and Mr. Binney 

 of ^lanchester, that the plant called Stigmaria (Fig. 38) is not a 

 separate genus, but the root of Sigillaria (Plate IV. Figs. 1 and 

 2). The name is derived from oTty/xa, a mark, indicating the 

 markings on the axis. It is one of the most common produc- 

 tions of the coal-measures, and consists of long rounded or 

 compressed fragments, marked externally by shallow circular, 



Fig. 38. Stigmaria ficoides, root of Sigillaria, giving off rootlets, 

 which have been compressed. 



Fig. 39. Stigmaria ficoides (S. Anahatlira of Corda), which is the root 

 of a Sigillaria. The markings are the points whence rootlets proceed. 



