EXPLANATIONS OF PLATE XLX. 



Calloqraptus elegans, page 134. 



Fig. 1. A fragment of a frond, natural size. 



" 2. A nearly entire flabelliform frond. The two shaded lines running nearly ver- 

 tically through the figure, are due to faults or slips in the slate, causing a 

 slight overlapping of the laminae, and an interruption of the continuity of 

 th'e frond. 



" 3. An enlargement, showing the lateral connection of the branches at irregular 

 intervals. 



" 4. A further enlargement of the non-celluliferous side of a bifurcating branchlet, 

 showing the striated surface and a semi-articulate structure. 



Callograptcs Salteri, page 135. 



Figs. 5, G. Fragments of two distinct fronds ; one showing the celluliferous side, and 

 the other the non-celluliferous side. 



" 7. An enlargement from the non-celluliferous side, showing a few transverse dis- 

 sepiments at irregular intervals. The figure has the same degree of 

 enlargement as fig. 3 of C. elegans. 



" 8. A farther enlargement of a bifurcating branchlet, showing the cell-apertures. 



