THE CARBONIFEROUS AGE. 127 



roots ; but at length their connection wi'ch Sigillaria 

 was observed simultaneously by Mr. Binney, in Lan- 

 cashire, and by Mr. Richard Brown, in Cape Breton, 

 and it has been confirmed by many subsequently ob- 

 served facts. This connection, when once established, 

 farther explained the reason of the almost universal 

 occurrence of Stigmaria, as these roots were called, 

 under the coal beds ; while trunks of the same plants 

 were the most abundant fossils of their partings and 

 roofs. The growth of successive generations of Sigil- 

 lariae was, in fact, found to be the principal cause 

 of the accumulation of a bed of coal. Two species 

 form the central figures in our illustration. 



Along with the trees last mentioned, we observe 

 others of a more graceful and branching form, the 

 successors of those Lepidodendra already noticed in 

 the Devonian, and which still abound in the Carboni- 

 ferous, and attain to larger dimensions than their 

 older relations, though they are certainly more abund- 

 ant and characteristic in the lower portions of the 

 carboniferous. Relatives, as already stated, of our 

 modern club-mosses, now represented only by com- 

 paratively insignificant species, they constitute the 

 culmination of that type, which thus had attained 

 its acme very long ago, though it still continues to 

 exist under depauperated forms. They all branched 

 by bifurcation, sometimes into the most graceful and 

 delicate sprays. They had narrow slender leaves, placed 

 in close spirals on the branches. They bore their 

 spores in scaly cones. Their roots were similar to 



