FLORA OF THE CARBONIFEROUS EPOCH. 



45 



right angles, and in alternate order, a series of sessile lanceo- 

 late leaflets, rather more than two inches in length, by abont 

 an eighth part of an inch in breadth, and about three lines 

 apart. Each is furnished mth a slender midrib ; and, 

 what seems a singular, though not entirely unique feature in 

 a Fern, the edges of each are densely hirsute, and bristle 

 with thick short hair. The venation is not distinctly pre- 

 served." 



Sigillaria (Plate IV. Figs. 1 and 2) is perhaps the most 

 important plant in the coal formation. The name is derived 

 from sigillum, a seal, to indicate the seal-like markings in the 

 stem. It is found in all coal-shales over the world. Schim- 



Shale 



ri£c. 33. 



Fi^. 34. 



per mentions 83 species. It occurs in the form of lofty 

 stems, 40-50 feet high, and 5 feet broad (Figs. 33 and 34). 

 Many stems of Sigillaria may be Seen near Morpeth, standing 

 erect at right angles to the planes of alternating strata of 

 shale and sandstone (Fig. 33). They vary from 10 to 20 feet 

 in height, and from one to three feet in diameter. Sir W. C. 



Figs. 33 to 37 exhibit forms of Sigillaria stems found in the 

 shales of the Carboniferous epoch. Fig. 33. Stem of Sigillaria ixichy- 

 clerma in an erect position, covered by successive deposits of sandstone 

 and shale ; one of the stems is bifurcated. Fig. 34. Sigillaria reni- 

 formis, with its external markings, and roots which are Stigmarias, as 



