228 Minnesota Algae 



Mill Pond, near Greenwich, Cumberland County. 1869. (Wood). 



421. Scytonema hirtulum (Kuetzing) Rabenhorst. Fl. Eur. Algar. 2: 265. 



1865. De Toni. Syll. Algar. 5: 531. 1907. 

 WoUe. Fresh-Water Algae U. S. 261. pi. 189. f. 7- 1887. (S y m p h y o- 

 siphon hirtulus Kg.). 



Plate XIII. fig. IS. 



Plant mass expanded, cushion-shaped, olivaceous-black, consisting of 

 spine-shaped, wick-like bundles of filaments; filaments and false branches 

 ID-IS mic. in diameter, ascending, slightly curved, parallel and more or less 

 densely agglutinated below, usually free at the apices, obtusely rounded; 

 sheaths colorless or yellowish, transparent, the external layers a little 

 swollen with age, roughened, 20 mic. in thickness; trichomes 8-10 mic. in 

 diameter; transverse walls distinct; cells equal to the diameter or a little 

 shorter; heterocysts both basal and intercalary, single or in pairs, oblong, 

 brown in color. 



United States. On moist rocks and damp earth. (Wolle). 



422. Scytonema immersum Wood. Contr. Hist. Fresh-Water Algae North 



America. 59. pi. 2. f. 9. 1872. De Toni. Syll. Algar. 5: 530. 1907. 



Intermingled with other algae and adhering to aquatic plants; fila- 

 ments about 10 mic. in diameter, elongate; false branches mostly in 

 pairs, more or less distant, short or elongate; sheaths wide, transparent, 

 colorless; apex of trichome obtusely rounded; transverse walls sometimes 

 distinct, sometimes invisible; cells quadrate or shorter than the diameter; 

 heterocysts distinct, single, intercalary, somewhat cylindrical, sometimes 

 half as long as broad, sometimes nearly twice as long; cell contents bright 

 blue-green. 



New Jersey. Forming a flocculent, greenish black, slimy coating to the 

 stems and finely dissected leaves of Ranunculus aquatilis. In 

 Shepherd's Mill Pond, near Greenwich, Cumberland County. 1869. (Wood). 



423. Scytonema polymorphum Naegeli. Rabenhorst. Fl. Eur. Algar. 2: 



257. i86s. De Toni. Syll. Algar. 5: 532. I907- 



Moebius. Ueber einige in Portorico gesammelte Siisswasser- und Luft- 

 Algen. Hedwigia. 27: 24s. 1888. 



Plant mass cushion-shaped, dark blue-green or blackish; filaments 

 7-27 mic. in diameter, variously curved, loosely entangled, sparingly 

 branched; false branches single or in pairs; sheaths colorless or yellowish 

 brown, transparent, lamellose; trichomes S.8-14.S mic. in diameter; trans- 

 verse walls visible or invisible; cells shorter or up to three times longer 

 than their diameter; heterocysts oblong, colorless or pale brown; cell con- 

 tents light blue-green or lead-colored. 



West Indies. Porto Rico. (Moebius). 



424. Scytonema rubrum Montagne. Premiere Centurie de Plantes Cellu- 



laires Exotiques. Ann. Sci. Nat. Bot. II. 8: 349. 1837; Histoire de 

 rile de Cuba. 9. 1838. De Toni. Syll. Algar. S: 532. 1907. 



