PLATE 40 G. 
Fig. 1. 570. 2. Dictyonema gracilis. ( Pag. 175.) 
1 a. A portion of a frond, showing the branches neatly defined, and spreading only in a moderate degree. 
1 b. A part of another frond, where the branches appear to spread more rapidly, hut 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. 176.) 
2 a. A part of several stems upon the surface of the shale. 
2 6. An enlarged portion, showing the structure. 
