NEW MYXOPHYCEAE FROM POKTO RICO 



67 



geneoiis, hyaline; reprodnction by small liorinogonia formed in 

 the upper part of the filament. 



Growing in a stream on stones in the vicinity of San Lorenzo, 

 no. 501, type ; in a pool about four kilometers north of Mayagiiez, 

 no. 1327 c ; on stones in the Turabo River near Caguas, no. 481. 



The material of this collection is very clean and in excellent 

 condition. Apparently every stage in the development is rep- 

 resented. There are many small hormogonia down at the base 

 of the mature specimens. Between these small specimens and 

 the old mature ones there are many gradations in size repre- 

 sented. The species is associated with Lynghya erecta, a species 

 attached at one end and the filaments erect and parallel. To- 

 gether these form a compact, velvety stratum on stones. 



Calothrix tenella sp. nov. 



Plate 13, figure 20 



Filaments 60-90 |j long, mostly tortuous, 10-12 \i at the base, 

 somewhat swollen above the base, tapering to a slender hair; 

 trichome 4.8-6'.2 n at the base ; cells quadrate to one-half as long 

 as the diameter, homogeneous; pale aeruginous to yellowish 

 green; heterocysts basal, spherical to subspherical, usually 

 smaller than the trichome in diameter; sheath smooth, hyaline, 

 thicker above the base. 



Growing on and among Hepaticae on rocks, near Maricao, no. 

 1036 a, type. 



Calothrix epiphytica AV. & G. S. West is probably the nearest 

 relative to the above species among all of the known species of 

 the genus. C tenella is a much shorter species with a more 

 ample sheath. 



Calothrix parietina torulosa var. nov. 



Filaments 400-700 m long, rigid, straight or in j^art with mod- 

 erate curves; tricliomes olive-green, decidedly torulose in the 

 lower part ; sheath narrow, firm and homogeneous, becoming 

 slightly lamellose and in part thickened later; a few of them 

 slightly ocreate, and yellowish-brown. 



In Rio Grande, near Sabana Grande, no. 914, type. 



Calothrix Braunii contorta var. nov. 



Filaments very much contorted, 500-800 p long ; trichomes 

 torulose at the base and 6-7.5 p diam., cylindrical above and 

 2.5-3 M diam. 



