Myxophyceae 213; 



390. Scytonema conchophilum Humphrey in Collins. The Algae of Jamaica. 



Proc. Am. Acad. Arts Sci. 37: 241. 1901. Collins, Holden and Setch- 



ell. Phyc. Bor.-Am. Fasc. 2. no. 52. 1895. 

 Plant mass having the form of gray, postular roughenings on shells; 

 filaments S-8 mic. in diameter, irregularly branched; false branches single 

 or in pairs, with rounded apices; sheaths rather thin, deep yellow, homo- 

 geneous, when old rough on the outside, colorless and thin at growing tips; 

 trichomes 2.7-4.5 mic. in diameter; cells two-thirds to twice as long as. 

 broad; heterocysts 5 mic. in diameter, spherical or slightly elongated, rarely 

 two or three together, intercalary; cell contents pale bluish green. 



West Indies. On old conch shell, Mastigocoleus testarum oc- 

 curring on inside of same shell. Port Antonio. March 1893; Kingston, 

 Jamaica. June 1897. (Humphrey). 



391. Scytonema arcangelii Bornet and Flahault. Revis. des Nostoc. Ann. 



Sci. Nat. Bot. VH. S: 92. 1887. De Toni. Syll. Algar. 5: 502. 1907. 



Collins. The Algae of Jamaica. Proc. Am. Acad. Arts Sci. 37: 241. 1901.. 



Plant mass cushion-shaped, 3-4 mm. in height, expanded, gray or 

 greenish; filaments 12-16 mic. in diameter, entangled in fascicles; false 

 branches long, flexuous; sheaths membranaceous, thin, colorless; trichomes. 

 10-14 mic. in diameter; cells disc-shaped or somewhat quadrate; hetero- 

 cysts somewhat quadrate, colorless or yellowish. 



West Indies. On moist rocks by spring. Castleton, Jamaica. April 1893.. 

 (Humphrey). 



392. Scytonema coactile Montagne in Kuetzing. Spec. Algar. 305. 1849. 



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

 5: 90. 1887. De Toni. Syll. Algar. 5: 501. 1907. 



Schramm and Maze. Essai Class. Algues Guadeloupe. 32. 1865. Maze 

 and Schramm. Essai Class. Algues Guadeloupe. 34-36. 1870-1877. (S. c o a c- 

 tile radians Crouan, S. elegans antillarum Crouan, T o 1 y p o- 

 thrix guadelupensis Crouan). Murray. Catalogue of the Marine. 

 Algae of the West Indian Region. Journ. of Bot. 27: 261. 1889. 



Plant mass caespitose, woolly, silky, radiately expanded, green or blue- 

 green, up to IS cm. in diameter; filaments 18-24 mic. in diameter, 4 cm. and 

 more in length; false branches long, erect, spreading; sheaths firm, mem- 

 branaceous, colorless or yellowish; trichomes 12-18 mic. in diameter; cells 

 somewhat quadrate or longer than the diameter; heterocysts somewhat rare,. 

 somewhat quadrate. 



West Indies. At first attached, finally floating free in stagnant water 

 (Perrottet, Montagne). 



393. Scytonema rivulare Borzi. Morfologia e Biologia delle Alghe Fico- 



cromacee. Nuovo Giorn. Bot. Ital. 11: 373. 1879. Bornet and Fla- 

 hault. Revis. des Nostoc. Ann. Sci. Nat. Bot. VII. 5: 91. 1887. De 

 Toni. Syll. Algar. 5: 501. 1907. 

 Tilden. American Algae. Cent. V. no. 479. 1901; Collection of Algae 

 from the Hawaiian Islands. Haw. Almanac and Annual for 1902. iii. 1901.. 



