56 Minnesota Algae 



Plate III. fig. 29, 30. 



Gonidangia 1-2 celled, 1-3 mic. in diameter at the base, 4-8 mic. in 

 diameter at the apex, 7-30 mic. in length, club-shaped or long cylindrical, 

 straight or curved, solitary or densely crowded in groups; tegument color- 

 less, at first closed, later open at apex; cell contents blue-green; gonidia 

 about 2 mic. in diameter. 



Maine. Attached to filamentous algae. Spring, College meadow, Orono. 

 (Harvey). Minnesota. In tank in Botanical Laboratory. University, Min- 

 neapolis, February 1896. (Tilden). Iowa. Growing on the surface of an 

 alga, probably an Oedogonium. Eagle Grove. Hewitt's Pond. 1904. 

 (Buchanan). West Indies. Growing on an Oedogonium. In warm 

 springs. Los Banos, near Coamo. Porto Rico. (Sintenis). 



125. Chamaesiphon curvatus Nordstedt. De Algis Aquae Dulcis et de 

 Characeis ex Insulis Sandvicensibus. 4. pi. I. f. I, 2. 1878. De Toni. 

 Syll. Algar. 5: 139. 1907. 

 Nordstedt. De Algis Aquae Dulcis et de Characeis ex Insulis Sand- 

 vicensibus a Sv. Berggren 1875 reportatis. 4. 1878. Lemmermann. Algenfl. 

 Sandwich.-Inseln. Bot. Jahrb. 34: 618. 1905. 



Plate III. fig. 31. 



Gonidangia many-celled, 3-10 mic. in diameter, 20-100 mic. in length, 

 somewhat cylindrical, more or less curved, rising from a narrow base; tegu-- 

 ment colorless; cell contents blue-green. 



Hawaii. Among filaments of Cladophora. Near Honolulu. Island 

 of Oahu. (Berggren). 



Order II. HORMOGONEAE 



Plants multicellular, filamentous, attached to a substratum or free-float- 

 ing; filaments simple or branched, usually consisting of one or more rows 

 of cells within a sheath; reproduction occurs by means of hormogones or 

 resting gonidia. 



Family I. Oscillatoriaceae. Filaments frequently branched, containing 

 one or more trichomes; sheaths variable, more or less gelatinous; trichomes 

 consisting of a simple row of cells uniform along their entire length, ex- 

 cept for the apical cells which sometimes taper more or less; heterocysts 

 absent; reproduction by means of vegetative division and hormogones. 



Family II. Nostocaceae. Sheaths very delicate, mostly confluent, usually 

 not visible; trichomes usually twisting and entangled, consisting of a single 

 row of uniform cells, with heterocysts; reproduction by means of vegeta- 

 tive division, hormogones and gonidia. 



Family III. Scytonemaceae. Filaments with a false branch system; 

 sheaths firm and tubular; trichomes consisting of a single row of cells, 

 but not of uniform thickness, with heterocysts; reproduction by means of 

 vegetative division, hormogones and gonidia. 



Family IV. StigOnemaceae. Filaments frequently branched; sheaths thick, 

 firm, often irregular; trichomes consisting of one or several rows of cells. 



