282 EXPLANATION OF 



8. Halimeda tuna, p. 139. 

 a. Of the natural size. 

 B. Of the natural size. 



PLA.TE Xll 



Fig. 1. Udoteajiabellata, p. 141. 

 Of the natural size. . 



2. Melobesla pustulata, p. 142. 



a. Polypidom of the natural size, on tlie Chon 



drus polymorphus. 

 B. The same, magnified. 



3. Melobesia farinosa, p. 142. 



Of the natural size, on a fucus leaf. 



4. Ahyonium lobatum, p. 243. 



a. Of the natural size, and dried. 



B. The transverse cut of a branch, also dried. 



PLATE XIII. 



Fig. 1. Alcyonium lobaUnn.^ p. 243. 



a. The entire Polypus out of its cell, with its 

 tentacula a little expanded, although en- 

 closed within a membrane. 



B. Polypus wholly expanded, the upper part. 



C. One of its tentacula detached. 



D. Polypus expanded at the opening of its 



cell. 



E. Polypus contracted. 



F. Vertical section of an expanded Polypus. 



