Myxophyceae 203 



H Plants living in salt water; heterocysts basal. 



1 Plant mass densely caespitose; filaments 6-7 mic. in diameter, thick- 



ened into a bulb at the base M. grisea 



2 Plant mass loosely caespitose; filaments 7-9 mic. in diameter, flex- 



uous, scarcely thickened at base 



M. vitiensis 



374. Microchaete tenuissima W. and G. S. West. On some Freshwater Algae 



from the West Indies. Journ. Linn. Soc. Bot. 30: 269. pi. 14. f. 

 7-1 1. 1895. De Toni. Syll. Algar. 5: 484. 1907. 

 West and West. A Further Contribution to the Freshwater Algae of 

 the West Indies. Journ. Linn. Soc. Bot. 34: 286. 1899. 



Plate X. fig. 10. 



Filaments 4.4-5.1 mic. in diameter, very slender, somewhat entangled, 

 twisted; sheaths transparent, colorless, wide; trichomes 1-1.8 mic. 

 in diameter; cells elongate, 5-16 mic. in length, the younger cells shorter 

 and wider; heterocysts 2-2.4 ™ic. in diameter, 3.5-6.5 mic. in length, some- 

 what quadrate or oblong, intercalary. 



West Indies. Amongst Symploca cuspidata on trees, summit 

 of Trois Pitons (4,500 feet). November and December 1892; on rocks, 

 Castle Bruce River (2,000-3,000 feet), Dominica. January and February 

 1896. (Elliott). 



375. Microchaete tenera Thuret. Essai Class. Nostochinees. 7. 1875. Bornet 



and Flahault. Revis. des Nostoc. Ann. Sci. Nat. Bot. VII. 5: 84. 



1887. De Toni. Syll. Algar. 5: 482. 1907. 

 Setchell. Notes on some Cyanophyceae of New England. Bull. Torr. 

 Bot. Club. 22: 427. 1S95. Setchell and Gardner. Algae of Northwestern 

 America. Univ. Calif. Pub. Bot. i: 194. 1903. 



Plate X. fig. II. 



Plant mass small, star-shaped; filaments 6-7 mic. in diameter, i mm. 

 in length, curved at the base, slightly flexuous; sheaths thin, close, uni- 

 form, colorless; trichomes 5 mic. in diameter; lower cells twice as long as 

 their diameter, upper cells equal in length to their diameter; heterocysts 

 basal, oblong, cylindrical, intercalary. 



Alaska. Forming gray tufts on dripping rocks. Walls of Amaknak 

 Cave, Amaknak Island, Bay of Unalaska. (Setchell and Lawson). Con- 

 necticut. Mixed with various, gelatinous algae, occurring upon dripping 

 rocks near Norwich and New Haven. (Setchell). 



376. Microchaete robusta Setchell and Gardner. Algae of Northwestern 



America. Univ. Calif. Pub. Bot. i: 194. 1903. De Toni. Syll. Algar. 



S: 483. 1907. 

 Plant mass forming a tuft or star-shaped cluster on water weeds; fila- 

 ments 16-18 mic. in diameter, elongate and extremely cylindrical, decum- 

 bent at the very base, but scarcely thickened; sheaths at first thin, later 

 becoming lamellose, colorless; trichomes 12 mic. in diameter, composed 



