NEW MYXOPHYCEAE FROM PORTO RICO 



81 



two to three orders remain intact instead of separating as is 

 usually the case. 



ScYTONEMA jAVANicuM pallidum vai". nov. 



Filaments flexuous, 9.5-12.5 m diam., densely intertwined, 

 forming a fiocculent stratum; trichomes not constricted, 7-9 p 

 diam. ; cells cylindrical throughout the trichome, quadrate to 

 slightly greater or less than the diameter, pale grayish or aeru- 

 ginous ; sheath thin, membranaceous, hyaline at the apices, 

 brown below. 



Growing on serpentine rock near Mayagiiez, no. 899 a, type. 



ScYTONEMA JAVANICUM distortum var. nov. 



Filaments 13.8-15 m diam., 200-300 \\ long, branching fre- 

 quent, mostly by bowing out of the trichome and later breaking 

 apart, much contorted; heterocysts numerous, much compressed. 



Growing on trees north of Mayagiiez, no. 1000, type. 



The variety is to be distinguished from the species by the 

 method of branching, the trichomes pushing out in the form of a 

 loop, and breaking in two later. The frequent branching of the 

 short filaments causes them to become much distorted. 



Scytonema multiramosum sp. nov. 



Plate 18, figure 39 



Filaments erect, entwined into dense fascicles more or less 

 agglutinated by the soft, slightly gelatinous sheaths, 1.5-2.5 n 

 long, 9.5-13 [X diam., profusely branched in pairs in the upper 

 parts of the filament between the heterocysts ; trichomes 7-8 n 

 diam. at the apices, gradually diminishing to 3 n diam. in older 

 parts ; apical cells slightly doliof orm, subquadrate, densely gran- 

 ular, other cells 1.5-4 times as long as the diameter ; heterocysts 

 quadrate to twice as long as the diameter; sheath thin at the 

 apices, gradually thickening as the trichomes diminish in size, 

 hyaline, and homogeneous when young, becoming yellowish and 

 laminated when old, the lamellae divergent, and slightly ocreate 

 at the apices. 



Growing on moist rocks about ten kilometers north of Utu- 

 ado, no. 1527, type. 



The young stages of this species of Scytonema very closely 

 resemble 8. suhgelatinostmi of this paper. The sheath when 



