EXPLANATIONS OF PLATE XxX. 
DICTYONEMA IRREGULARIS, page 136. 
Fig. 1. A fragment from near the base of a frond. 
“ 2. A fragment from the outer portion of the frond. 
DICTYONEMA ROBUSTA, page 137. 
Figs. 3, 4. Fragments of two different fronds. In some parts of the specimen fig. 3, and 
in all of fig. 4, the branches are extremely flattened and attenuate. 
DICTYONEMA QUADRANGULARIS, page 138. 
Fig. 5. A fragment of a frond, of the natural size. 
DicryonemA Murrayi, page 138. 
Figs. 6, 7. Fragments of two fronds ; the figures of the natural size. 
