NEW MYXOPHYCEAE FROM PORTO RICO 41 



Tlie filaments of the variety are smaller and the cells shorter 

 than those of the species, which is an inhabitant of salt water. 

 The filaments at times completely encircled the host. 



Lyngbya Martenstana minor var. nov. 



Plate 8, figure 80 



Filaments 250-500 u long, moderately flexuous, 7.2-8 n diam. ; 

 trichomes 4.8-5 \i diam., not constricted ; bright blue-green ; cells 

 very short, 1.4-1.8 n long, with fine grannies along the cross- 

 walls ; apical cell capitate ; tegmnent hyaline, homogeneous, 

 smooth, about 2 m thick. 



Growing on limestone among other Myxophyceae between 

 Hatillo and Arecibo, no. 1392 h, type. 



Lyngbya intermedia sp. nov. 



Plate 9, figure 82 



Filaments lon.g and more or less arcuate, 20-22 \x diam. ; tri- 

 chomes 17-20 |j diam. ; cells 4.5-5.5 m long, congested with gran- 

 ules away from the cross-walls, 1-2 apical cells attenuated, 

 slightly thickened, or capitate ; sheath hyaline, firm, smooth, not 

 lamellose. 



Growing in a pool among numerous other algae about four 

 kilometers north of Mayagiiez, no. 1316 h, type. 



PoRPHYROsiPHON NoTARisii major var. nov. 



Filaments 22-28 m diam. ; trichomes 18-23 n diam. ; cells quad- 

 rate to one-third the diameter long, aeruginous; sheath rela- 

 tively thin, homogeneous and hyaline when young, finally be- 

 coming thicker, pink, and somewhat lamellose when older. 



Growing on rocks in the vicinity of Coamo Springs, no. 6008, 

 type, collected by Dr. N. L. Britton; on soil along the road to 

 San Lorenzo, no. 523; on soil north of Sabana Grande, nos. 980, 

 931, and 935 a. 



Porphyrosiphon robustus sp. nov. 



Plate 9, figure 83 



Filaments closely intertwined, forming a loose floccose 

 stratum, of moderate length, 30-36 \\ diam. ; trichomes not con- 

 stricted, neither attenuated nor capitate, 16-20 \x diam. ; cells one- 

 third to one-half as long as the diameter, homogeneous, bright 

 aeruginous, cross-walls very distinct ; apical cell rounded, wall 



