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 celluliferous surface. 
1 e, f. Parts of figs. 1 c and 1 d, still further enlarged. 
Fig. 2. 556. 6. Retepora asperato-striata. ( Pag. 161.) 
2 a. A fragment of the base with the point of attachment, showing the exterior surface of an expanded 
funnel-shaped frond. 
2 b. 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 frond, where the interstices are smaller than in 
the preceding. 
2 d. An enlargement of the striated surface, showing the asperate character of the striae. 
2d \. A still farther enlargement of the surface, showing the character of the papulous surface. 
2 e,/. The celluliferous'side of two fragments of this species. . g .• 
2 g, h. Enlargements from the two preceding fragments, showing the difference in form and arrangement of 
the cells. 
Fig. 3. 557. 1. 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. 
