Myxophyceae 241 



1896; Observations on some West American Thermal Algae. Bot. 

 Gaz. 25: 97. pi. 9. f. io-<3. 1898. De Toni. Syll. Algar. 5: 565. 1907. 



Plate XV. fig. 1-4. 



Plant mass widely expanded, bright blue-green in color; filaments 

 branched; branches single or in pairs, sometimes abruptly bent; trichomes 

 3-6 mic. in diameter, sometimes cylindrical with indistinct transverse walls, 

 sometimes consisting of very long cells or short somewhat quadrate cells 

 or even spherical cells, the latter up to 11 mic. in diameter; heterocysts 8 

 mic. in diameter, 8-16 mic. in length, intercalary, oblong, barrel-shaped. 



Wyoming. Completely coating bed of very swift mountain rivulet, at 

 vent of hot spring. Temperature of spring 61° C. The growth of the plant 

 begins here and disappears at a distance of fifty-five feet from spring where 

 the temperature is 51° C. The most luxuriant growth is thirty-five feet 

 from the spring at a temperature of 54° C. On a mountain near Lower 

 Geyser Basin, Yellowstone National Park. June 1896. (Tilden). Oregon. 

 In hot spring. Temperature 55° C. Cascade Mountains, lat. 45° 20'. 1895. 

 (Lloyd). 



"The filaments of H. major are nearly twice the diameter of H. 

 1 a m i n o s u s Hansg. An important character of the latter plant is its 

 habit of forming crystals of lime, according to Cohn who studied the 

 plant at Carlsbad. The Yellowstone species occurred in silicious waters 

 only, at least it was not discovered at Mammoth Hot Springs, where the 

 waters contain calcium carbonate." — Tilden. 



444. Hapalosiphon intricatus West and West. On some Freshwater Algae 



from the West Indies. Journ. Linn. Soc. Bot. 30: -271. 1895; A 

 Further Contribution to the Freshwater Algae of the West Indies. 

 1. c. 34: 286. 1899. De Toni. Syll. Algar. 5: 571. 1907. 



Plate XV. fig. S. 



Plant mass caespitose, small, blue-green; filaments 4-7 mic. in diameter, 

 densely interwoven and variable, sparingly branched, containing a single 

 row of cells; branches single, unilateral, flexuous, similar to the primary 

 filament, with or without a sheath; mature sheaths close, usually distinct; 

 cells variable, up to three times longer than their diameter, often equal and 

 somewhat rotund, or elongate; heterocysts 3.8-5.5 mic. in diameter, one 

 to three times longer than diameter, somewhat quadrate or oblong, scat- 

 tered. 



West Indies. In little intricate tufts among the leaves of L e u c o- 

 b r y u m, on trees, summit of Trois Pitons (4,500 feet), Dominica. Novem- 

 ber, December 1892; in stream, Wotten Waven, Dominica, January, Feb- 

 ruary 1896. (Elliott). 



445. Hapalosiphon arboreus West and West. On some Freshwater Algae 



from the West Indies. Journ. Linn. Soc. Bot. 30: 272. 1895. De 

 Toni. Syll. Algar. 5: 572. 1907. 



