494 



HISTORICAL GEOLOGY 



and had, consequently, somewhat the general outline of our forest 

 trees, but with that the resemblance ended. The leaves were numer- 

 ous and slender and were commonly arranged in oblique rows 

 about the trunk and branches. When shed, their bases left diamond- 

 shaped scars which gave a characteristic appearance to the bark 

 (Fig. 471). The largest Lepidodendron trunk yet described was 

 found to be 114 feet long up to the point 

 where it began to branch ; the diameter 

 of the base was about three feet, while 

 at a height of 114 feet it was one foot, 

 showing that it was a tree of slender 

 proportions. Other species, however, 

 were of a somewhat sturdier build. 



The Sigillaria (Latin, sigillum, seal) 

 differed externally from the Lepidoden- 

 dron, especially in two particulars; it 



Fig. 471. — Impression of the bark of 

 the Lepidodendron, showing the leaf bases 

 .and characteristic diamond-shaped scars. 

 (See Fig. 470.) 



Fig. 472. — Restoration of 

 Sigillaria, showing the position 

 and character of the leaves and 

 the fruit, and the peculiar bark. 

 (See Fig. 473.) Some of them 

 grew to a height of a hundred 

 feet, with a diameter of six feet. 



branched sparingly (Fig. 472) and the leaves were arranged in 

 vertical rows (Tig. 473), the leaf scars on the bark giving rise to the 

 name " seal tree." In some species the leaves were a yard long. 

 Sigillarian trunks almost as slender and high as those of the Lepi- 

 dodendron have been found, but, as a rule, they were shorter and 



