56 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



when young, later opened and the trichomes extruding; tri- 

 chomes straight, ahiiost parallel in the sheath, not constricted at 

 the cross-walls, long and very sharply acuminate at the apices ; 

 1.8-2.2 M diam. ; cells pale aeruginous, homogeneous, 2-4 times as 

 long as the diam.; apical cell longer and very sharp, conical; 

 cross-walls obscure ; sheath hyaline, irregular along the margin, 

 somewhat mucous. 



Growing on a church wall, Sabana Grande, no. 952 d, type ; 

 on the soil, between Hatillo and Arecibo, no. 1366 & ; on a wall in 

 Fort San Cristobal, San Juan, no. 1991 e. 



The nearest approach in relationship to this species of MiQro- 

 coleus, so far as is known, seems to be M. tenerrimus Gomont, a 

 salt-water species. The plants of that species are larger, of a 

 deeper color, and especially not so long and sharply attenuated 

 at the apices. 



Microcoleus amplus sp. nov. 



Plate 11, figure 3 



Filaments tortuous, mostly open at the apices with extruding 

 trichomes, smaller, younger ones closed ; 30-60 trichomes densely 

 entwined in the center of the filaments, 4.6-5 ^ diam., very bright 

 blue-green in color, 2-3 cells attenuated at the apices, not con- 

 stricted at the dissepiments ; cells quadrate to twice as long as 

 broad, densely congested with fine irregular granules; cross- 

 w^alls very distinct; apical cell conical; sheath white, smooth, 

 homogeneous, ample, 9-12 n thick. 



Growing on mud by a stream near Rio Piedras, no. 72, type ; 

 on earth at the Experiment Station, Eio Piedras, no. 179 \ on 

 earth, Utuado, nos. 1505 and 1573. 



Microcoleus amplus has close affinities with M. vaginatus 

 Gomont, M. paludosus Gomont, and M. lacustris Farlow. From 

 the first it differs in not having capitate trichomes and in having 

 longer cells; from the second in having smaller trichomes and 

 shorter cells ; and from the last in not having constricted or 

 dolioform cells, and in having more acute apices. It ditfers 

 from all three in having a more ample sheath. 



Microcoleus purpureus sp. nov. 



Plate 11, figure 4 



Filaments 15-25 p (up to 50 m) thick, acuminate, scattered 

 promiscuously among other algae, more or less contorted, closed 



