IV. DICTYOTACE^.— DicTYOsiPHON. 113 



Plate IX. B. Fig. 1. Frond of Stilophoea rhizodes, the natural size ; Jig. 2, a 

 small portion of a branch, with its wart-like sori, magnified ; fig. 3, section of a 

 sorus, and of a portion of the frond ; fig. 4, a spore and paranema ; the latter 

 figures highly viagnified. 



2. Stilophoea j»ap;7/osa, J. Ag. (?) ; frond cylindrical, many times dichotonious, 

 with very patent angles and divaricating, attenuated apices ; the dichotomous 

 branches and their lesser divisions clothed with very many slender horizontal, hair- 

 like ramuli. /. Ag. Sp. Alg. vol. \,p. 84. (?) 



Hab. Chesapeake Bay, Prof. J. W. Bailey, (v. s.). 



I am not satisfied that the plant from the Chesapeake, which I introduce more on 

 my friend Prof. Bailey's authority than my own, is the same as the Mediterranean 

 species described by Agardh ; nor, indeed, am I quite certain that it belongs to 

 this genus. I have examined one of the original specimens, presented to me by 

 Prof. Bailey, and had intended figuring it, but have not been able to make out the 

 microscopical characters to my satisfaction. The above specific diagnosis applies 

 very well to the specimen. But Meneghini's figure, {Alg. Ital. t. 3, /. 2,) quoted 

 by Agardh for his species, is very unlike our plant. I have seen no authentic example 

 of the Mediterranean S. papillosa, and thus am unable fully to decide on the 

 identity of the American ; and, in this uncertainty, think it better to place the 

 species on record, in the hope that future observation may clear the subject in one 

 way or other. My specimen is about four inches square in the spread of the 

 branches, and it scarcely adheres to the paper on which it has been dried. 



VII. DICTYOSIPHON. Grev. 



Boot a small, naked disc. Frond filiform, tubular, much branched ; its walls 

 composed of several rows of cells, of which the inner are elongated, and connected 

 into longitudinal filamentous series ; the outer or supei'ficial small, coloured, poly- 

 gonal, forming a membrane. Fructification : solitary or aggregated, naked spiores^ 

 scattered irregularly over the surface. 



When young the fi'ond is solid, but the cells forming the axis, which are of 

 larger size than the rest, are also weaker and soon perish, leaving the stem and 

 branches fistular. Li a growing state every branch is clothed with long, slender, 

 pellucid, jointed hairs, which give the plant, when seen under water, a beautifully 

 feathery character. Similar hairs are seen on many others of the Order, and are 

 doubtless connected with the development of the frond. The walls are composed 



VOL. in. AET. 4. Q 



