FOSSIL FLORA. 61 



PLATE XXII. 



" Warty Stigmakia." 



{Stigmaria ficoides, Brongniart. 

 Phytolithus verrucosus, Martin's Petrificata Derbiensia, PI. II. 



Ficoidites verrucosus, of Artis.) 



In this species of Stigmaria the tubercles vary considerably in size, and give a verrucose, 

 or warty, aspect to the surface. The specimen figured on a small scale, fig. 2, and a portion 

 of the natural size, fig. 1 , was between five and six feet in length, and four inches in diameter. 

 A gi'oove visible on the external surface indicates the inner axis, which by compression has 

 been pressed from its natural central position ; see fig. 2, a, b, c, d : figs. 6, 7, 8, 9, show in the 

 corresponding transverse sections the position of this body. 



The mode of attachment of the rootlets to the tubercle on the main root, is represented 

 fig. 5. Fig. 3, exhibits the characters of the two kinds of variolse, or tubercles. 



When Dr. Buckland's Bridgewater Essay was published, the true nature of these fossil 

 remains was unknown. It was supposed by Messrs. Lindley and Hutton, that the original was 

 an aquatic plant, having a short dome-shaped trunk, from which radiated numerous long 

 horizontal branches; and that when the plant was perfect, and the branches floating on the 

 water, its appearance resembled that of an Asterias.' This dome-shaped trunk is now known 

 to be merely the base of the stem of the tree. See Supplementary Notes, art. Stigmaria. 



' Dr. Buckland's Bridgewater Essay, vol. ii. p. 95. 



