Myxophyceae 215 



mann. Algenfl. Sandwich-Inseln. Bot. Jahrb. 34: 624. 1905. Tilden. 



American Algae. Cent. VII. Fasc. i. no. 632. 1909. 



Plate XI. fig. IS. 



Plant mass caespitose, entangled, woolly, green, becoming brown or 

 olive; filaments 16-36 mic. in diameter, 3 cm. and more in length, curled, 

 branched; sheaths firm, membranaceous, colorless, rarely becoming brown- 

 ish; trichomes 14-30 mic. in diameter; cells three times shorter than their 

 diameter; heterocysts depressed or quadrate, sometimes numerous, some- 

 times almost none. 



Greenland. Abundant in "Lyngemarken Spring, September." (Dickie). 

 Rhode Island. In abundance near Providence. (Osterhout). Connecticut. 

 Near Lanesville; on rock below Factory Pond; ditch at North Haven. 

 September, November. (Holden). Forming extensive dark green woolly 

 masses in stagnant water. North Haven. October 1891. (Setchell). Penn- 

 sylvania. In a pond near Bethlehem. (Wolle). Florida. (Coe). Illinois. 

 Lakeside, Cook County. May (Johnson and Atwell). Minnesota. Lily 

 Lake, near Stillwater, Washington County. August 1908. (Tilden). Ne- 

 braska. In ponds. Nebraska City. (Bessey). Colorado. (Brandegee). 

 West Indies. In reservoir. Botanic Garden, Castleton, Jamaica; on sides of 

 trough, Constant Spring; in basin, Kingston. April 1893. (Humphrey). 

 Hawaii. In ponds. Nuanu, Oahu. (Berggren). Floating in mats on surface 

 of stagnant water among roots of Water Hyacinth, on beach. Meheiwa, 

 Makao, Koolauloa, Oahu. June 1900. (Tilden). 



"The filaments vary very much. Sometimes both branches and hetero- 

 cysts are rare and the species looks very much like a Lyngbya, very 

 often the scanty branches occur single and adjacent to a heterocyst and 

 it resembles greatly a Tolypothrix, while the geminate branches mid- 

 way between two heterocysts, characteristic of Scytonema are generally 

 found only after long and careful search." — Setchell. 



396. Scytonema caldarium Setchell. Notes on Cyanophyceae. — III. Erythea. 

 7: 48. pi. 3. f. 3. 1899. Collins, Holden and Setchell. Phyc. Bor.-Am. 

 Fasc. 12. no. 559. 1899. 



Plate XII. fig. I. 



Plant mass forming more or less extended tufts; filaments 16 mic. in 

 diameter, decumbent or even horizontal at base, more or less entangled, 

 branched; false branches in pairs, erect, twisted together into Symploca- 

 like tufts, 8-lS mm. high; erect filaments 12-16 mic. in diameter, seldom or 

 only singly branched; sheaths firm, lamellose, with parallel layers, colorless, 

 soon becoming a deep yellowish brown; trichomes 4-8 mic. in diameter; 

 cells 3-12 mic. in length; heterocysts discoid to quadrate in the younger 

 portions of the filaments, cylindrical in older portions, colorless; cell con- 

 tents uniformly coarsely granular, olive or yellowish green. 



California. Growing on cooler portions of the rocks from which the 

 hot water drips. Temperature of the tufts 27° C. Waterman Hot Springs, 

 near San Bernadino. April 1897. (Parish). 



