PLATE 40 C. 



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



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



1 b. A .strong liranch 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 ftirther enlarged. 



Fig. 2. 656. 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 



funiiel-sliaped frond. 

 2 J. 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. 

 2 d t- 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. 



2 g, A. 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 o, i. A bifurcating fragment, natural size, and a part of the surface enlarged, showing the form and ar- 



rangement of the cells. 

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



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