Ch. XXIV.] 



STIGMARIA. 



475 



Dr. Hooker still inclines to the belief that the gigillarice may have 

 been cryptogainous, though more highly developed than any flowerless 

 plants now living. The scalariform structure of their vessel agrees pre- 

 cisely with that of ferns. 



Stigmaria. — This fossil, the importance of which has already been 

 pointed out, was formerly conjectured to be an aquatic plant. It is 

 now ascertained to be the root of Sigillaria. The connection of tbe 

 roots with the stem, previously suspected, on botanical grounds, by 

 Brongniart, was first proved, by actual contact, in the Lancashire coal- 

 field, by Mr. Binney. The fact has lately been shown, even more dis- 

 tinctly, by Mr. Richard Brown, in his description of the Stigmaria? 

 occurring in the underclays of the coal-seams of the Island of Cape 

 Breton, in Nova Scotia. 



In a specimen of one of these, represented in the annexed figure 

 (fig. 528), the spread of the roots was sixteen feet, and some of them 

 sent out rootlets, in all directions, into the surrounding clay. 



Fisr. 52S. 



Stigmaria attached to a trunk of Sigillaria.* 



In the sea-cliffs of the South Joggins in Nova Scotia I examined 

 several erect Sigillaria?, in company with Dr. Dawson, and we found 

 that from the lower extremities of the trunk they sent out Stigmarice 

 as roots. All the stools of the fossil trees dug out by us divided into 

 four parts, and these again bifurcated, forming eight roots, which were 

 also dichotomous when traceable far enough. 



The cylindrical rootlets formerly regarded as leaves are now shown 

 by more perfect specimens to have been originally attached to the root 

 by fitting into deep cylindrical pits. In the fossil there is rarely any 

 trace of the form of these cavities, in consequence of the shrinkage of 

 the surrounding tissues. Where the rootlets are removed nothing 

 remains on the surface of the Stigmaria but rows of mammillated tuber- 

 cles (see figs. 529, 530), which have formed the base of each rootlet. 

 These protuberances may possibly indicate the place of a joint at the 

 lower extremity of the rootlet. Rows of these tubercles are arranged 

 spirally round each root, which have always a medullary axis and 



* The trunk in this case is referred by Mr. Brown to Lepidodendron, but his 

 illustrations seem to show the usual markings assumed by Sigillaria near its base. 



