38 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



Oscillatoria obtusa sp. nov. 

 Plate 8, figuke 73 



Triehoines straig-ht or arcuate, moderately rigid, 23-25 n 

 diain., bright aeriiginons, straight and not attenuated at the 

 apices, or very slightly bent and narrowed in the last two or 

 three cells, terminal wall slightly thickened; cells 4-6 times 

 shorter than the diameter, homogeneous ; cross-walls very thin 

 1)ut plainly visible. 



Growing in a pool in Borinquen Park, Santurce, no. 807, 

 type ; in Turabo Kiver near Caguas, no. 486 a; in a ditch near the 

 Playa, Fajardo, no. 696 e. 



Oscillatoria refringens sp. nov. 



Plate 8, figure 74 



Trichomes bright aeruginous, rigid or more or less flexuous, 

 not constricted at the dissepiments, two or three end cells 

 slightly tapering, not uncinate, terminal wall thickened; termi- 

 nal cell somewhat enlarged, 9-10 m diam. ; cells short, 1.8-2 n 

 long, with occasional biconcave, refringent cells, slightly larger 

 than the trichome, interspersed, homogeneous. 



Growing among water plants in the Turabo Kiver, Caguas, 

 no. 486 h, type, and no. 478; upon water plants, Jayuj^a, no 1756. 



The biconcave, refringent cells are sufificiently abundant in a 

 mass of trichomes to characterize the species, but there are some 

 trichomes, especially young trichomes, which have none. The 

 mature filaments develop a characteristic end resembling very 

 much Oscillatoria prohoscidea but the end is straight and the 

 trichome is less in diameter than in that species. It is also close 

 to 0. auguina Bory, but lacks the attenuated terebriform apices 

 characteristic of that species. 



Lyngbya erecta sp. nov. 



Plate 8, figure 75 



Filaments relatively straight and more or less parallel, at- 

 tached at one end, forming a dense velvety stratum, 4-7 mm. 

 long, 3.5-4 LI diam. ; trichomes 1.4-1.6 \\ diam., not constricted at 

 the dissepiments, not attenuated at the apices ; cells mostly quad- 

 rate, but varying from slightly shorter to 2 times as long as 

 the diameter, cross-walls moderately conspicuous, apical cell 



