may possibly occur also along the southern coast, though no 

 specimens have been sent to me therefrom. It belongs to the 

 same section as A. stelligera, but differs from that in its tricho- 

 tomous but not lohorled ramification, in the proportions of its 

 joints, the short nodes, different arrangement of fruit, etc. It 

 is perhaps more nearly allied to A. intermedia, but has longer 

 joints, different ramification, etc. 



Fig. 1. Amphiroa gracilis, — the natural size. 2. Sterile apex of the frond. 

 3. A fertile apex, warted with ceramidia. 4. Frustule of a joint, with a 

 ceramidium, after the lime has been removed by acid. 5. Tetraspores. 

 6. Some of the cellular tissue of the axils : — varmisly magnified. 



