70 



MEMOIRS OF THE NEW YORK BOTAXICAL GARDEN 



Calothrix simulans sp. nov. 



Plate 13, figure 23 



Filaments 7-9 m diani., cylindrical except for a short distance 

 in the apical portion, prostrate at the hase, curving away from 

 the host and becoming free, 200-250 n (up to 400 m) long; 

 trichomes 6-7 m diam., cylindrical, except at the outer end where 

 it suddenly tapers into a short hair about 2 n diam., constricted 

 slightly at the dissepiments ; cells quadrate to one-third as long 

 as the diameter, aeruginous, densely congested with small irreg- 

 ular granules; heterocysts basal, single, spherical to subspher- 

 ical, 6.8-7.2 n diam. ; sheath very thin, tirm, hyaline, close-fitting 

 and uniform throughout; spores 1-3-seriate at the base just 

 above the heterocyst, cylindrical, 8-9.5 n diam., 12-16 m long. 



Growing in water west of the Experiment Station, Eio Pie- 

 dras, no. 1946, type. 



This species of Calothrix described above is similar in the 

 cylindrical character to C. evanescens and to C. linearis of this 

 palmer, and especially in the possession of spores, the only spe- 

 cies in the Porto Kican collection having this character. The 

 plants are epiphytic upon a large species of Oedogonium. After 

 the hairs disintegrate, the specimens resemble very closely mem- 

 bers of the genus Microcliaete. 



Dichothrix Willei sp. nov. 



Plate 14, figure 24 



Filaments about 1 mm. high, forming a dense flocculent stra- 

 tum, profusely branched, 12-15 |j diam. ; trichome narrow, 7-9 \x 

 at the base, very gradually attenuated, ending abruptly, about 

 2.5-3 M diam. at maturity, extending into a hair when young, con- 

 stricted very slightly only at the base ; cells quadrate, pale 

 greenish or bluish green, densely congested with small granules; 

 cross- walls very thin, in part very inconspicuous ; sheath thick, 

 subgelatinous, as thick as or thicker than the trichome, hyaline 

 when young, homogeneous, changing later to yellowish or honey- 

 color and very finely lamellose; heterocysts hemispherical to 

 spherical at maturity, same diameter as the trichome; branched, 

 2-5 remaining within a common sheath for only a short dis- 

 tance, the sheath merely enlarging, not ocreate. 



Growing in a ditch on rocks by the road about ten kilometers 

 north of Utuado, )io. i.5.54,type, and nos. 1555,1541, 1566, 1527 h, 

 and 1539 d. 



