PLATE 40 C. 



Fig. 1. 555. 5. Retepora diffusa. • (Pag. 160.) 



1 a. A part of a frond of this species, natural size. 



1 6. A strong branch with numerous bifurcating branchlets, which are thickened at their extremities. 



1 c. A portion of the striated surface enlarged. 



1 d. A similar enlargement of the cclluliferous surface. 



1 e, f. Parts of figs. 1 c and 1 d still further enlarged. 



Fig. 2. 556. 6. Retepora asperato-striata. ( P^g- 161.) 



2 a. A fragment of the base with the point of attachment, showing the exterior surface of an expanded 



funnel-shaped frond. 

 2 6. A portion of a similar frond, showing the external or striated surface. 

 2 c. A smaller fragment, showing the root with a part of the fronds where the interstices are smaller than in 



the preceding. 

 2 d. An enlargement of the striated surface, showing the asperate character of the striae. 

 2 d \. A still farther enlargement of the surface, showing the character of the papulous surface. 

 2 e, f. The celluliferous side of two fragments of this species. 



2 g, h. Enlargements from the two preceding fragments, showing the difference in form and arrangement of 



the cells. 



Fig. 3. 557. ]. Hornera.? dichotoma. (Pag. 163.) 



3 a. b. A bifurcating fragment, natural size, and a part of the surface enlarged, showing the form and ar- 



rangement of the cells. 

 3 d. The striated or non-celluliferous surface, natural size and enlarged. 



