88 



MEMOIRS or THE NEW YORK BOTANICAL GARDEN 



Growing on damp fern roots and on soil about twenty kilo- 

 meters north of Ponce, no. 1810, type. 



This form of Stigonema may readily be distinguished from 

 the other forms of S. hormoides by the thin wall, which is deeply 

 constricted at the dissepiments of the trichome. 



Stigonema hormoides nodulosum var. nov. 



Filaments 8-9 m diam., short, very crooked and nodular; cells 

 close together, subspherical ; tegument thin, firm, homogeneous, 

 dark brown; branches very sparse, short; heterocysts sparse. 



Growing on rocks in a waterfall of a warm stream, Coamo 

 Springs, no. 310, type. 



Stigonema hormoides rigidum var. nov. 



Filaments 250-350 p long, 8.5-10 \x diam., moderately curved, 

 sparsely l^ranched, firm and rigid; cells in youngest specimens 

 cylindrical, quadrate to one-half the diameter long, later becom- 

 ing dolioform to subspherical ; tegument thin, close-fitting, firm, 

 homogeneous, dark brown. 



Growing on red earth near Mayagiiez, no. 880 f, type. 



Stigonema hormoides lineare var. nov. 



Filaments 300-500 p long, comparativel}^ straight, sparsely 

 branched, with branches as long and of the same dimensions as 

 the main frond, 7-8 n diam., sheath very thin, smooth, hyaline at 

 first, soon changing to yellowish; cells finely granular. 



Growing on soil at the Experiment Station, Rio Piedras, no. 

 117a, type. 



In this form of 8. hormoides the sheath is very thin and the 

 cells stand close together. In the young and rapidly growing 

 stage the filaments resemble those of a species of Phormidium. 



Stigonema elegans sp. nov. 



Pl.\TE 20, FIGURE 51 



Filaments 400-500 n long, 16-20 \i diam., with longer or 

 shorter curves, forming a more or less flocculent stratum; 

 branches not abundant, of two sorts, one short and pointed, hor- 

 mogoniferons, and the other like the main axis, arising at right 

 angles, not attenuated; cells in part uniseriate and in part pluri- 



