NEW MYXOPHYCEAE FROM POKTO RICO 



85 



The very much contorted habit and the secretion of granules 

 on the sheath, coupled with the combination of other characters 

 mentioned above distinguish this species of Hassalia. 



Hassalia fragilis sp. nov. 



Plate 20, figure 4G 



Filaments 5.5-7 m diam., very short, straight and rigid, form- 

 ing a thin velvety stratum ; trichomes 4-5.5 |j diam. ; cylindrical 

 throughout the entire length, not constricted at the dissepi- 

 ments; cells quadrate in the older parts about one-half as long 

 as broad at the apices of the trichomes ; aeruginous, more or less 

 finely granular ; heterocysts spherical to somewhat compressed, 

 numerous, appearing very generally at the base of the filaments 

 caused by the separation at the point of the more or less con- 

 tinuous and profuse branching; sheath thin, homogeneous, hya- 

 aline, close-fitting, readily dissolved at the point of false branch- 

 ing of the trichome. 



Growing on old wood at Hacienda Catalina, Palmer, no. 747 c, 

 type ; on trees in a ravine near Coamo Springs, no. 1896 h. 



This is a species of Hassalia with affinities close to H. Bou- 

 teillei (Breb. & Desm.) Born. & Flah., but differing in several 

 minor details. 



Tolypothrix papyracea sp. nov. 

 Plate 20, figxjee 47 



Filaments woven into a very firm, dense, thin stratum, rela- 

 tively short, 6-7 M diam. ; trichomes 3.6-4 n diam., of uniform 

 diameter throughout their entire length except 1-3 cells at the 

 apices, slightly attenuated, constricted at the dissepiments ; cells 

 quadrate when in rapid division, 3-4 times as long as the diam- 

 eter in the mature parts of the trichome, bright aeruginous, 

 homogeneous, or with a few fine granules ; cross-walls conspicu- 

 ous; heterocysts sparse, cylindrical, diameter slightly greater 

 than the trichome; sheath thin, firm, smooth, hyaline; branches 

 erect. 



Habitat and exact locality not given. Collected by Dr. Walter 

 C. Earle in the vicinity of Manati, Porto Rico. 



Tolypothrix penicillata brevis var. nov. 



Filaments 1-2 mm. long, intermixed with other filamentous 

 algae, main filaments 18 n diam., branches smaller; trichomes 



