1925 J Setchellr-Gardner : Melan-ophyceae 527 



20. Myelophycus Kjellm. 



Fronds filiform, attached by numerous rhizoidal filaments densely 

 interwoven, solid throughout when young, later becoming hollow 

 above; growth trichothallic (?), later usually intercalary; fronds 

 composed of three kinds of tissue, an inner, colorless layer of a few 

 rows of large, rounded, isodiametric, or elongated cells, outside of 

 which is a layer of small prismatic, thick-walled cells giving rise to a 

 dense mass of erect, assimilating filaments (paraphyses ?) ; zoo- 

 sporangia immersed among the assimilating filaments; gametangia 

 unknown ; hairs present in the juvenile stage. 



Kjellman, in Engler and Prantl, Natiirl. Pflanzenfam., 1893, 86 

 Lief., p. 202, Om Fuc. Myelophycus, 1893, pp. 1-11. 



The type species of the genus is M. caespitosum from the coast of 

 Japan. The species of our coast seems to agree in all generic require- 

 ments. Kjellman has followed the neuter gender of the Greek noun, 

 phykos, although the Latin form would indicate a grammatical 

 masculine. It seems best, however, to follow Kjellman as being more 

 in accord with the proper usage. 



We place this genus in Asperococcaceae with considerable doubt. 

 The species may prove to be the zoosporangial forms of gametangial 

 plants similar to Chordaria Gunjii Yendo. 



Myelophycus intestinale Saunders 



Fronds solitary or loosely caespitose, 1-15 dm. high, 2-4 mm. diam., 

 solid in the juvenile stage, hollow at maturity above the short, solid 

 stipe, cylindrical, abruptly attenuated at the tip, but later eroded, 

 usually twisted, unbranched, dark reddish brown in color; central 

 tissue composed of 2-3 layers of elongated, cylindrical, colorless cells 

 merging toward the outside into 3-4 irregularly arranged rows of 

 thick-walled, cuboidal cells, these in turn giving rise to numerous 

 paraphyses composed of 4-8 thick-walled cells and to zoosporangia ; 

 zoosporangia ellipsoidal to obovate scattered over the frond except the 

 stipe, 45-60/x long, 20-30/* broad. 



Growing attached to rocks in the lower littoral and upper sub- 

 littoral belts. Shumagin Islands, Alaska, to Puget Sound, Washington. 



"Myelophycus imtestinalis" Saunders, Alg. Harriman Exp., 1901, 

 p. 420 ; Setchell and Gardner, Alg. N.W. Amer., 1903, p. 241. 



