NEW MYXOPHYCEAE FROM PORTO RICO 



49 



This very diminutive and decidedly unique member of the 

 Myxopliyceae presents important difficulties to one in attempt- 

 ing to classify it. Its position within the tegument of Micro- 

 coleus may be the determining factor in causing it to resemble 

 Symploca in habit without having any real affinities with that 

 genus. No branching was observed. 



Symploca roseola sp. nov. 



Filaments 2-2.5 \\ diam., closely intertwined, forming dense, 

 microscopic, conical fascicles ; trichomes 1-1.3 n diam. ; cells 

 quadrate to 2.5 times as long as the diameter ; apical cell blunt, 

 contents jaale aeruginous, homogeneous, rose-pink. 



Growing among other Myxophj^ceae on damp rocks about ten 

 kilometers north of Utuado, no. 1032 h, type. 



Hypheothrix acutissima sp. nov. 



Plate 10, figure 9-1 



Filaments not branched, more or less flexuous; trichomes 

 sparse, 1-5, a-nd closely associated in the sheath, 7-7.5 m diam., 

 short, rigid, straight for the most part; apices sharply attenu- 

 ated for 7-10 cells, moderately constricted at the dissepiments; 

 cells quadrate or slightly longer or shorter than the diameter, 

 homogeneous, pale aeruginous, cross-walls thin but conspicuous ; 

 sheath thin, membranaceous, hyaline and homogeneous, close 

 fitting. 



Growing on moss along the way north of Maricao, no. 1271 a, 

 type. 



The material of this collection is sparse, but quite distinct. 



The specimens upon which this species of Hypheothrix is 

 founded are not typical of the genus in every particular. The 

 sheath is thin and close-fitting, and when only a single trichome 

 appears within a sheath, a condition of common occurrence, 

 there is no way to distinguish it from the genus Phormidiuni. 

 When several are closely entwined within a sheath it resembles 

 some species of the genus Microcoleus, although typically that 

 genus has a more ample sheath and more trichomes are asso- 

 ciated within it. The size of the trichomes and their paucity 

 within a sheath relate the species to those of the genus Hydro- 

 coleum as founded by Kuetzing," and as emended by Gomont.* 



7 Phycologia generalis, 196. 1843. 



8 Monographie des Oscillaiiees. Ann. Sci. Nat. Bot. VII. 15: 332. 1892. 



