PLATE 40 G. 



Fig. 1. 570. 2. DiCTTONEMA GRACILIS. ( Pag. 175.) 



1 a. A portion of a frond, showing the branches neatly defined, and spreading only in a moderate degree. 

 1 6. A part of another frond, where the branches appear to spread more rapidly, but have otherwise the 



essential characters of the preceding. 

 1 c, e. Enlargements, showing the indented or corrugated surface of the branches. 



1 d. An enlargement of several branches, where the margins appear indented or subserrate. 



Fig. 2. 571. 1. Inocaulis plumulosa. (Pag- l''^.) 



2 a. A part of several stems upon the surface of the shale. 

 2 6. An enlarged portion, showing the structure. 



