MARINE ALGM OF BEAUFORT, N. C. 445 



This species is visible as minute dots under a strong lens and is easily recognized under the micro- 

 scope by the external hemispherical tufts of paraphyses and sporangia arising from widely scattered 

 internal filaments. The internal filaments may be traced for long distances through the host. In 

 European specimens the "unilocular sporangia" are the more abundant, but in the Beaufort plants 

 these are very rare, and the " plurilocular sporangia" are abundant. 



This species has not previously been recorded for North America. 



Family 4. CHORDARIACE^ (Agardh) Zanardini. 



Frond convex-discoid or pulvinate, hemispherical or globose and finally hollow, or 

 filiform and regularly branched, more or less slippery, sometimes almost gelatinous; 

 segmented hairs always present; longitudinal growth terminal or subterminal; surface 

 covered by short assimilating filaments; "plurilocular sporangia" formed either by the 

 transformation of some segments of these filaments, or (like the "unilocular sporangia") 

 in the place of filaments, or arising laterally on the filaments. 



About 65 species, in all seas, especially in North Atlantic. 



KEY TO GENERA. 



a. Frond forming a horizontally expanded, parenchymatous, monostromatic disk with upright 



assimilating filaments i. Myrionema (p. 445). 



a'a. Frond forming a more or less large, upright body b. 



b. Longitudinal growth by transverse division of subterminal cells of the axial fila- 

 ment, assimilating filaments secondary; axial body of the frond composed of series 



of cells solidly joined together; filiform, branched 2. Castagnea (p. 446). 



bb. Longitudinal growth by transverse division of the upper segments of free apical 

 filaments, the upper divisions finally changed into assimilating filaments; axial 

 body of the fertile frond composed of rows of cellular filaments many times 

 furcate, more or less loosely connected, anastomosing; hemispherical to sub- 

 globose 3. Leathesia (p. 447). 



Genus i. Myrionema Greville. 



Myrionema, Greville, 1827, vol. 5, pi. 300. 



Thallus consisting of a very minute, horizontally expanded, round, or oblong disk 

 composed of a single layer of rather closely packed cells, from which arise numerous 

 erect, monosiphonous, assimilating filaments; sporangia arising from the basal disk on 

 more or less elongated stalks; "unilocular sporangia" ellipsoidal or pear shaped, "pluri- 

 locular sporangia" silique shaped, at least in the lower part, consisting of several series 

 of cells, usually borne on different plants, sometimes on the same plant. 



Two to four species, on other plants, mostly in the North Atlantic Ocean and the 

 Mediterranean Sea. 

 Myrionema strangulans Greville. 



Myrionema strangulans, Greville, 1827, vol. 5, pL 300. 



Myrionema stranyulans, Harvey, 1852, p. 133. 



Myrionema vulgare, Farlow, 1882, p. 79. 



Myrionema stranyulans, De Toni, 1895, p. 399. 



P. B.-A. Nos. i79s, 280 (M . Leclanckerii), 32. 924. 1689 (M. vulgare). 



Thallus forming minute spots more or less expanded over other plants, basal layer composed of 

 elongated, segmented filaments almost joined into a membrane, with cells about 1.5 diameters long, 

 vertical filaments numerous, densely crowded, club shaped, with short cells, intermixed with hyaline, 

 confervoid filaments with elongated cells; "unilocular sporangia" obovoid, about 30 to 40 mic. long, 

 19 to 27 mic. wide, arising from the basal layer, borne on short stalks or almost sessile; "plurilocular 

 sporangia' ' unknown. 



North Atlantic and Mediterranean. 



