78 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



pletely separating them. As the successive cells diminish in 

 diameter, the sheath becomes correspondingly thicker, and fin- 

 ally many cells completely disappear. 



ScYTONEMA MiRABiLE majus var. nov. 



Filaments 1-2 mm. high, 22-28 n diam. ; trichomes 9-14 ij 

 diam. ; cells purplish gray, finely granular in part. 



Growing on damp rocks about five kilometers north of Utuado, 

 no. 1617, type; about ten kilometers north of Utuado, no. 1563. 



Scytonema lyngbyoides sp. nov. 



Plate 17, figure 35 



Filaments forming a dense velvety stratum, or more or less 

 intertwined and pannose, 28-32 [j diam. in main filaments, 

 branches as small as 20 \i diam. ; trichomes 18-25 \i diam., more 

 or less constricted at the dissepiments ; cells one-third to one- 

 sixth as long as the diameter, bright violet to olive-green, homo- 

 geneous ; cross- walls thin, but distinct ; heterocysts of the same 

 shape and size as the cells, hyaline, sparse ; sheath hyaline, 

 homogeneous ; branching geminate for the most part, occasion- 

 ally single. 



Growing on rocks in a brook about five kilometers north of 

 Utuado, no. 1607, type ; on rocks between Utuado and Adjuntas, 

 no. 1646. 



The violet or dark olive-green color of the trichomes, the 

 homogeneous hyaline sheath, the sparsity of the hyaline hetero- 

 cysts, and the lack of abundant branching, characteristic of the 

 above newly described species, remind one at first sight of the 

 genus Lyngbija; hence the specific name. 



Scytonema tenue sp. nov. 



Plate 17, figure 36 



Filaments mostly straight, erect, parallel, closely associated, 

 forming a velvety stratum, sparsely branched, the branches aris- 

 ing near the base, 0.75-1 mm. high, 6-8 m diam.; trichomes 5.5- 

 6.5 M diam. at the apices, 2-2.5 times as long in older parts ; cells 

 cylindrical in the body of the filament, and not constricted, 

 slightly dolioform at the apices, pale aeruginous, homogeneous ; 

 sheath subgelatinous, hyaline, homogeneous, 2-2.5 [i thick ; het- 

 erocysts cylindrical, quadrate to 2 times as long. 



