EASTERN BORDERS. 299 



Mr. Binney and Mr. Richard Brown, who have found the Stigmaria 

 roots united with Sigillaria stems. As, however, this root is most 

 commonly found detached, we place it under its ordinary name in 

 our Fossil Flora. 



Stigmaria ficoides (Brong.). Ref. Lindley and Hutton's Fossil 

 Flora, t. 31-36. 



Localities. Frequent in the district in sandstones and shales. 



Plate XII. Compressed rootlets of Stigmaria ficoides in a light- 

 coloured, argillaceous, and slightly calcareous rock, from the hanks 

 of the Whiteadder opposite Hutton Mill. 



Genus Sigillaria (Brong.). 



Sigillarise were large trees with simple or branching stems, which 

 are fluted longitudinally, and marked between the furrows by regular 

 rows of scars, the remains of the leaf-insertions. So large were they, 

 that fragments have been found 3 feet in diameter and 60 feet 

 long. Their fruit is not known, but leaves of two species have been 

 found, — those of Sigillaria lepidodendrifolia by Brongniart, and of 

 Sigillaria Rhytidolepis by Corda ; those of the latter are Unear, very 

 long, and narrow, being from 1 to 2 feet long, and only ^-th of 

 an inch in breadth. 



To Brongniart we are indebted for an elaborate and skilful exposition 

 of the structure of Sigillaria. It is similar to that of Stigmaria, but 

 more complicated ; a large cellular column is surrounded by a narrow 

 vascular or woody cylinder, broken mto wedges and crossed by 

 medullary rays. A longitudinal section of the woody tissue, made both 

 parallel and at right angles to the medullary rays, shows the walls of 

 thevessels to be marked with parallel transverse bars; these are enclosed 

 in a broad zone of cellular tissue ; but, in addition, a distinct set of 

 vascular bundles is placed opposite the small end of the woody wedges, 

 representing the medullary sheath of exogenous trees, and from these, 

 other bundles of striated vessels pass into the leaves. This structure 

 differs widely from that of any living plant ; it is, however, essentially 

 acrogenous; and the nearest analogue to these majestic trees of other 

 times is the Lycopod or lowly creeping Club-Moss ; yet the radial 

 arrangement of the woody tissue, and the presence of medullary rays and 

 a sheath, bring them into a distant relationship to exogenous vegeta- 

 tion. Brongniart considers them allied both to the Lycopod and to 

 the Cvcas ; they form, therefore, a cormecting link between Orders, 

 which stand far apart in existing nature. 



Composed chiefly of cellular tissue, Sigillarise were extremely suc- 

 culent ; they grew in swamps and marshes, their long and numerous 

 Stigmaria roots and rootlets forming an entangled mass, and permea- 

 ting the mud iu all directions, in a manner similar to that of the 

 living water-lily in shallow lakes and ponds. The roots sometimes 

 exhibited a crucial arrangement, uniting into four main portions. 



