NEW MYXOPHYCEAE FKOM TORTO KICO 



57 



at the apices when young-, dissolving, and tlie trichomes protrud- 

 ing at the apices when older, with the trichomes crowded close to 

 each other in the center and more or less intertwined but finally 

 separating into separate strands and forming new filaments; 

 trichomes up to 60 or more within a sheath, mostly parallel, 1.7- 

 1.9 M diam., pale puri^lisli-drab, not constricted, with acute and in 

 part uncinate apices ; cells homogeneous, 3-4 times as long as the 

 diam. ; sheath hyaline, homogeneous, somewhat gelatinous and 

 irregular along the margin. 



Growing on a wall in Fort San Cristobal, San Juan, no. 

 1991 d, type ; on a wall in a cemetery, San Juan, no. 130 a. 



MicROCOLEUS PALUDOSUS acuminatus var. nov. 



Plate 11, figure 5 



Trichomes few in a sheath, 5-G n diam., pale aeruginous, 3-5 

 cells at the apices tapering to a very sharp point, and in part 

 slightly uncinate. 



Growing on a wall in Fort San Cristobal, San Juan, no. 

 2013 a, type. ■ - 



The material of this species is very sparse, only a few fila- 

 ments having been observed and those growing among a very 

 small species of moss. 



MiCROcoLEUs sociATUs minot var. nov. 



Plate 11, figure 6 



Trichomes up to 75 in a sheath, 1.8-2.5 \i diam., not con- 

 stricted, pale aeruginous changing to yellowish green on drying ; 

 cells homogeneous. 



Growing on limestone among other algae between Hatillo 

 and Arecibo, no. 1392 a, type ; on a wall in an old cemetery, San 

 Juan, no. 130 & ; in a water reservoir, west of the Experiment 

 Station, Kio Piedras, no. 200 ; on a wall, Coamo Springs, no. 

 254 & ; on a wall by a bridge to Santurce, no. 143 h ; on the wall of 

 a church, Sabana Grande, no. 952 6 ; on a wall in Fort San Cristo- 

 bal, San Juan, nos. 2006 a, 2020 a, and 2021 c. 



Hydrocoleum rufescens sp. nov. 



Filaments containing 1-5 trichomes, mostly straight, or 

 somewhat tortuous, smooth, unbranched, narrow, spindle-form. 



