27 



X. Ginannia. Mont. 



Membranaceous, gelatinous, fibrous axis. Cells hexagonal. Fruit 

 spherical, immersed in the frond. 

 G. furcella ta, Turner ; Florida. 



XI. Catenelea. Greville. 



Frond membranaceous, filiform, constricted. Fruit, spherical 

 spores, in external capsules. Tetraspores immersed in the outward 

 cells. 



C. Sp. 1 or new ; Florida. 



XII. Crouania. J. Ag. 



Frond gelatinous, jointed, single tubed filaments. Fruit, spores 

 at the base of the whorled ramuli. Tetraspore very large, also at 

 the base of the ramuli. 



C. attenuata, J. Agardh; Key West. 



XIII. Rhabdonia. Harvey. 

 R. Baileyi, Harvey. 



Order VII.— CERAMIACEiE. 



Filiform frond, of jointed branching filaments of single strings of 

 cells. Fruit, berry-like receptacles, angular spores. Tetraspores 

 on the ramuli or immersed in the branches, Contains seven genera, 

 namely — 



I. Ptilota, Ag. — Name, winged. 

 II. Ceramium, Rothwell. — Name, a pitcher. 

 ' III. Spyredia, Harvey. — Name, a basket. 

 IV. Griffithsia, Ag. — Name, Mrs. Griffiths. 

 V. Wrangelia, Ag. — Name, Baron Von Wrangel. 

 VI. Seirospora, Harvey. — Name, a chain of seeds. 

 VII. Callithamnion, Lyngb. — Name, a beautiful little shrub. 



Genus I. — Ptilota. Ag. 



Main frond inarticulated. Ramuli jointed, pinnated. Spores 

 surrounded by short ramuli. Tetraspores attached to or immersed 

 in the ramuli. 



P. plumosa, Lamour ; Mass. Bay. 



P. sericea, Gmelin ; Providence. 



II. Ceramium. Roth. 



Frond filiform, articulated, and usually coated by colored cellules. 

 Fructification sessile, roundish .favellse, with minute angular spores. 

 Tetraspores immersed in the ramuli. 



C. rubrum, Hudson ; common. 



C diaphanum, Ag. ; common. 



C.fastigiatum, Harvey; N. Y. Bay. 



C. nodosum, Kiitzig ; L. I. Sound.^ 



