42 



MEMOIRS OF THE XEW YOKK BOTANICAL GARDEN 



not thickened; sheath rigid, at first hyaline, homogeneous, later 

 changing to pale rose-pink and becoming decidedly lamellose, 

 the ends usually extending much beyond the trichomes, and be- 

 coming collapsed and more or less lacerated. 



Growing on rocks among moss, etc., about four kilometers 

 north of Utuado, no. 1570, type ; on red soil at Hacienda Holm, 

 Mayagiiez, no. 1185 a. 



Phormidium calidum olivaceum var. nov. 



Filaments scattered among other algae, not forming a defi- 

 nite stratum, relatively short, flexuous, 7-8 n diam; trichomes 

 5.8-6.8 M diam., straight at the apices and not attenuated, or 1-2 

 apical cells slightly attenuated and uncinate, capitate, frequently 

 interrupted in the sheath ; cells quadrate to one-third diam. long, 

 homogeneous, dark olive-green or grayish green; sheath very 

 thin, smooth, homogeneous, hyaline. 



Growing on rocks among Hepaticae, and in association with 

 other algae, about seven kilometers east of Coamo, no. 1870 e, 

 type. 



The above-diagnosed variety of P. calidum Gomont may be 

 distinguished by the interrupted character of the trichome, 

 which in some specimens is broken into numerous parts which 

 gravitate some distance from each other, by the darker color, 

 and by the less pronounced capitate apical cells. 



Phormidium scytonematicola sp. nov. 

 Filaments short, crooked, forming a more or less compact 

 layer on the filaments of the host, prostrate, with the ends free 

 and more or less erect, 2. .3-3 \\ diam. ; cells quadrate to 3 times 

 as long, pale aeruginous, protoplast homogeneous ; cross-walls 

 inconspicuous ; apices straight, blunt, not capitate ; sheath very 

 thin, inconspicuous. 



Growing in depressions in rocks and on Scytonema at Haci- 

 enda Catalina, Palmer, no. 747 a, type ; on rocks by the road 

 north of Maricao, no. 1252 a. 



This species of Phormidium is so abundant on some of the 

 filaments of the host as to bind them into small symplocoid fasci- 

 cles, and appears to restrict their gro^^i;h. 



Phormidium scytonematicola minus var. nov. 

 Trichomes 1-1.5 m diam.; sheaths distinct, more or less con- 

 fluent when densely aggregated, pale rose-pink in color. 



