268 Minnesota Algae 



484. Calothrix thermalis (Schwabe) Hansgirg. Beitrage zur Kenntniss der 



Bohmisch. Thermalalgenflora. Oesterr. Bot. Zeitschrift. 34: 279. 



1884. Bornet and Flahault. Revis. des Nostoc. Ann. Sci. Nat. Bot. 



VII. 3: 368. 1886. De Toni. Syll. Algar. 5: 625. 1907. 

 Weed. Formation of Travertine and Silicious Sinter by the Vegetation 

 of Hot Springs. U. S. Geol. Survey. 9th Ann. Report. 665. 1889. (M a s t i- 

 gonema thermale Schwabe). Tilden. American Algae. Cent. III. 

 no. 287. 1898. Observations on Some West American Thermal Algae. Bot. 

 Gaz. 2$: 94. pi. 9- f. i-S. 1898. 



Plate XVIII. fig. i-S. 



Plant mass mucous, smooth, more or less expanded, deep olive green, 

 when dried blue-green; filaments 8-10 mic. in diameter, up to 3 mm. in 

 length, interwoven, flexuous, densely crowded; sheaths somewhat thick, 

 uniform, transparent, sometimes yellowish at the base; trichomas 5-8 mic. 

 in diameter, tapering at the apex into a long hair, here and there con- 

 stricted at the joints; cells equal to or three times shorter than the diame- 

 ter; heterocysts basal and rarely intercalary. 



Wyoming. Olive colored, forming sinter. Crater of Excelsior Geyser; 

 overflow of channel of geyser, temperature 49-54.5° C, Spasmodic Geyser; 

 forming cedar-colored fur on overflow channel of Old Faithful Geyser, Up- 

 per Basin, 1897. (Weed). With other algae in rivulets. Temperature 49-50° < 

 C. Fountain Hotel Geyser Basin. June 1896; very common in colder por- 

 tions of overflows, temperature 34° C, Emerald Pool, Upper Geyser Basin, 

 July 1896, Yellowstone National Park. (Tilden). 



485. Calothrix calida P. Richter in Kuntze. Revisio Generum Plantarum. 



Part III. II. 388. f. a, b. 1898. De Toni. Syll. Algar. 5: 626. 1907. 



Plate XVIII. pi. 6, 7. 



Plant mass 6 mm. in thickness, dry, spongy or crustaceous, widely ex- 

 panded, flattened, olivaceous; filaments 8-10 mic. in diameter, interwoven 

 flexuous, aggregated; sheaths close, yellowish brown, when young trans- 

 parent, thick, ocreate, ocreae here and there dilated; trichomes 3-6 mic. in 

 diameter, pale blue-green, tapering into a long hair; cells spherical or 

 elliptical, equal to their diameter, or three times longer, the lower ones 

 spherical depressed or barrel-shaped; transverse walls often inconspicuous; 

 heterocysts basal and intercalary, spherical or quadrate. 



Wyoming. In warm water from a geyser. Temperature +50° R. 1874. 

 Yellowstone National Park. (Kuntze). 



486. Calothrix kuntzei P. Richter in Kuntze. Revisio Generum Plantarum. 



Part III. II. 388. f. a-c. 1898. De Toni. Syll. Algar. 5: 625. 1907. ' 

 Plant mass dry, crustaceous, pulvinate, mammillose, stony, expanded, 

 faded within, blue-green on the surface, lamellose, up to 5 mm. in thick- 

 ness; filaments lo-ii mic. in diameter, free, usually agglutinated in irregu- 

 lar fascicles, parallel or flexible; sheaths close, thick, transparent and yel- 

 lowish, lamellose, ocreate; trichomes thickened at the base, especially when 

 young, bright bluish in color; basal cells hemispherical or spherical, barrel- 

 shaped or disc-shaped, those in upper portion of trichome oval or spheri- 



