SIGILLARIA 205 



trunk found at L'Escarpelle, near Valenciennes, in 

 France, which was traced for a distance of 22 metres 

 (over 70 feet). At the lower end it had a diameter 

 of 60 cm. (about 2 feet), which at the upper 

 extremity had only diminished to 50 cm. (1 foot 

 8 inches). The stem was thus a slender, nearly 

 cylindrical shaft. Both this and other, even longer, 

 trunks, reaching a length of 30 metres (nearly 100 feet) 

 were unbranched. In some cases the large stems are 

 found still clothed with leaves in their upper part. 

 Thus M. Grand'Eury 1 describes a stem of Sigillaria lepi- 

 dodendrifolia, which, for a distance of 3 metres (nearly 

 10 feet) from the top downwards, was covered by rigid 

 and erect linear leaves, more than a metre in length. 

 The foliage of Sigillaria is in some cases scarcely to be 

 distinguished from that of Lepidodendron, and as we 

 shall see below, the agreement extends to histological 

 structure. The stems of Sigillaria are often found 

 connected at the base with their subterranean organs, 

 which we will provisionally call roots, though their 

 morphological nature is doubtful, and will have to be 

 discussed later on. These roots (known under the 

 name of Stigmarid) are extremely common in the 

 " underclay " of the Coal-measures, immediately below 

 the seams of coal, and no doubt belong to the same 

 plants, the stem and leaves of which have contributed 

 to form the coal itself, the underclay representing the 

 soil in which the trees grew. It is usually, however, 

 impossible to say whether the root-like organs belonged 

 to a Sigillaria or a Lepidodendron. Fig. 85 shows an 

 enormous specimen of the stumps and roots of one of 

 1 Flore carbonifire du Dfyartement de la Loire, p. 156. 



