74 



MEMOIRS OF THE KEW YORK BOTANICAL GARDEN 



Scytonema subgelatinosum sp. nov. 



Plate 15, kiguke 29 



Filaments erect for the most part, more or less fasciculate, 

 sparsely branched, about 1 mm. long, 10-13 m diam. ; trichomes 

 clavate at the outer apical end, 3-5 p diam. in the older parts, 

 6-9 |j diam. at the apices ; cells up to 24 n long, cylindrical or 

 slightly dolioform in the middle and older parts, decidedly dolio- 

 form at the apices in some of the younger filaments, pale aeru- 

 ginous, homogeneous ; cross-walls very inconspicuous ; hetero- 

 cysts of the same size and shape as the cells ; sheath relatively 

 thick, subgelatinous, homogeneous, hyaline; branching mostly 

 single but some geminate. 



Growing on rocks by a water reservoir in Rio Piedras, no. 

 108, type; on rocks at the Experiment Station, Rio Piedras, no. 

 174; on rocks by the road to Monte Montoro, Mariacao, no. 

 1066; north of Maricao, no. 1246. 



Scytonema variabile sp. nov. 



Plate 15, figure 30 



Filaments mostly straight or arcuate, more or less coalesced 

 into erect fascicles about 2 mm. high, sparsely branched, both 

 single and geminate types of branching being represented ; main 

 filaments 34-42 n diam., branches smaller, all filaments very vari- 

 able in diameter in different parts; trichomes very variable in 

 diameter in different parts of the same filament, usually a little 

 larger at the apices than in the main body of the filament, up to 

 25 |j diam. ; cells cylindrical, slightly constricted at the dissepi- 

 ments to decidedly dolioform, mostly quadrate or less, in part 

 2 times as long as the diameter, bright aeruginous, in part homo- 

 geneous, and in part congested with granules; heterocysts as 

 variable in shape and size as the cells; sheath hyaline to yellow- 

 ish brown ; 6-12 \x thick, homogeneous or with a few divergent 

 laminae, subocreate, subgelatinous. 



Growing among moss on a waterpipe by a stream near Mari- 

 cao, no. 1149 a, type, and no. 1153. 



This interesting species of Scytonema belongs equally well 

 in either section II, Myochrotes Born. & Flah., or section III, 

 Petalonema Berk., as aranged by Forti.^* The sheath becomes 

 relatively thick and remains homogeneous in some parts of some 

 of the filaments. In others there are a few laminae and they 



14 In I)e Toni, Syllogo Alganim 5: 510, 526. 1907. 



