NEW MYXOPHYCEAE FROM PORTO RICO 



37 



constricted at the dissepiiiients ; cells aeni^inous, (juadrate to 2.5 

 times as long as the diameter, homogeneous, apical cell very 

 sharjily conical and uncinate, cross-walls inconspicuous. 



Collected by Dr. W. C. Earle in the vicinity of Manati, Porto 

 Kico, growing attached to water-inhabiting plants or free. 



This is a very small but distinct species of Oscillatoria be- 

 longing to the Attenuatae section of the genus as outlined by 

 Gomont. 



Oscillatoria granulata sp. nov. 



Plate 8, figure 71 



Plants not forming a distinct stratum, but interspersed 

 among other algae; trichomes relatively long and flexuous, 

 neither constricted nor attenuated, 3.4-3.8 \\ diam. ; cells for the 

 most part quadrate, conspicuous by the presence of granules at 

 the distinct cross-walls ; apical cells blunt, end wall slightly 

 thickened. 



In a pool at the Park, Santurce, no. 51 h, type. 



The species is especially marked by the large granules 

 crowded at the cross-walls. In mature specimens even the ter- 

 minal walls have them. The terminal wall is not very conspicu- 

 ously thickened. 



Oscillatoria claricentrosa sp. nov. 



Plate 8, figure 72 



Stratum inconspicuous; trichomes relatively straight and 

 rigid, 2.3-2.5 ,u diam., apices straight or slightly uncinate, acute, 

 very slightly constricted at the cross-walls ; cells up to 11 n long, 

 3-5 times as long as the diameter, though usually 6-8 m long ; 

 protoplast with a clear central area, the denser colored portion 

 free from granules, crowded close to the periphery; cross-walls 

 indistinct. 



Forming a thin stratum on mud in a ditch near Playa, Fa- 

 jardo, no. 697, type. 



This species belongs in the i^ttenuatae section of Gomont 

 (Monogr. p. 224) and is closely akin in form to Oscillatoria 

 longearticulata Hansg. and narrower than 0. acum inata Gomont. 

 It is to be distinguished by its relatively long cells with con- 

 spicuously clear centers free from granules. It is larger in 

 diameter than 0. longearticulata and narrower than 0. acumi- 

 nata. 



