PLATE XIX. 



A. IriDvEA, page 150. 



Fig. 1, I.eduUs; the natural size. 2, section of a 

 frond with favellidia. 3, section of a frond with 

 tetraspores. 4, tetraspores ; all magnified. 



B. Kallymenia, page 149. 



Fig. 1, K. reniformis, the natural size. 2, section 

 through a favellidium. 3, a tetraspore, from another 

 specimen ; both magnified. 



C. GiNANNiAj page 148. 



Fig. 1, G. furcellata; the natural size. 2, small por- 

 tion of the frond. 3, longitudinal, and 4, transverse 

 sections of the same, the latter showing immersed 

 favellidia ; all magnified. 



D. Halymenia, page 148. 



Fig. 1, H. Ugulata, the natural size. 2, cross section 

 of the frond. 3, a favellidium. 4, spores. 5, por- 

 tion of the surface cells ; all magnified. 



I 



