92 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



Stigonema spinifenim is closely related to S. cornutum of 

 this paper, but differs from that species in having larger cells, 

 fewer series of cells, and particularly in having all of the vege- 

 tative branches terminating in long, more or less curved, hyaline 

 spines, bearing the hormogonia, whereas in S. cornutum the hor- 

 mogoniferous branches are specialized. 



Stigonema scytonematoides sp. nov. 



Plate 22, figure 57 



Filaments relatively short and straight, 125-175 n long, 23- 

 27 M thick, sparsely branched ; branches similar to the main 

 frond, blunt and rounded; cells uniseriate, compressed-spheri- 

 cal, when old and dried drawn out somewhat at the poles, show- 

 ing distinct protoplasmic connections, bluish-green, homogene- 

 ous, 11-13 M diam. ; heterocysts similar to the cells in shape, size, 

 and form ; sheath thick, subgelatinous, faintly lamellose, particu- 

 larly so toward the apices where the laminae turn outward and 

 backwards from several cells, yelloAvish brown; hormogonia 

 short and blunt. 



Growing on red earth north of Maricao, no. 1250, type; on 

 red earth near Mayagiiez, no. 880 e ; on rocks by the road north 

 of Maricao, nos. 1245, 1250, and 125S a ; on rocks between Utu- 

 ado and Adjuntas, no. 164.3; on rocks, Arroyo de los Corchos, 

 no. 1715. 



It is somewhat troublesome to distinguish the above new spe- 

 cies of Stigonema from certain species of Hassalia. There are 

 many filaments in both genera which do not show branching. 

 Both have heterocysts very similar, being formed from an orig- 

 inal cell of the filament, whereas in many species of the genus 

 Stigonema for the most part the heterocyst is formed from a 

 part of an original cell produced by a longitudinal division. It 

 can readily be distinguished, of course, when the branching can 

 be observed, and especially by the short, blunt, hormogoniferous 

 branches. Stigonema scytonematoides seems closely related to 

 S. elegans of this paper. The sheath is wider and lamellose, the 

 cells are more nearly spheres in form, and the diameter of the 

 filament is greater than in that species. 



