102 Minnesota Algae 



Hawaii. On sides of wooden irrigation flume where water dripped through. 

 Kahuku Plantation, Oahu. June 1900. (Tilden). 



201. Phormidium interruptum Kuetzing. Tab. Phyc. i: 33. pi. 45. f. 7. 1845. 



De Toni. Syll. Algar. 5: 228. 1907. 



Plate IV. fig. 75. 



Plant mass membranaceous, mucous, blue-green; sheaths firm; trich- 

 omes S-6.5 mic. in diameter, iiexuously curved, interrupted; apex of trich- 

 ome straight, obtuse; cells 2.5-3.2 mic. in length; transverse walls some- 

 times finely granulated; cell contents usually homogeneous, yellowish 

 green. 



Vermont. Charlotte. (Wolle). 



202. Phormidium naveanum Grunow in Nave. Vorarbeiten zu einer Kryp- 



togamenflora von Mahrens. Verhandl. der Naturforsch. Vereins in 

 Briinn. 40. 1864. De Toni. Syll. Algar. 5: 228. 1907. 

 Wolle. Fresh Water Algae. Bull. Torr. Bot. Club. 6: 283. 1879; Fresh- 

 Water Algae U. S. 298. pi. 201. f. i, 2. 1887. 



Plate IV. fig. 76. 



Plant mass thin, dull green becoming olive brown; filaments 15-18 mic. 

 in diameter, more or less parallel; sheaths very wide, loosely cohering, firm, 

 colorless; trichomes frequently interrupted; cells two or three times shorter 

 than the diameter, indistinct; cell contents dull green. 



Canada. Crystal Bay, Ontario, Lake Erie. (Wolle). Pennsylvania. 

 Pools. (Wolle). Florida, Marsh grounds. (Smith). 



203. Phormidium retzii (Agardh) Gomont. Essai Class. Nostocacees homo- 



cystees. Morot. Journ. de Bot. 4: 355. 1890; Monogr. Oscill. 195. pi. 



5. f. 6-9. 1893. De Toni. Syll. Algar. 5: 241. 1907. 

 Wolle. Fresh Water Algae. Bull. Torr. Bot. Club. 6: 283. 1879; Fresh- 

 Water Algae U. S. 302. pi. 202. f. 9-1 1. 1887. (L. retzii Ag,, L. papyrina 

 Kirchn.) Bennett. Plants of Rhode Island. 114. 1888. Tilden. Ameri- 

 can Algae. Cent. I. no. 70. 1894. List of Fresh-Water Algae collected in 

 Minnesota during 1894. Minn. Bot. Studies, i: 235. 1895. Collins, Holden 

 and Setchell. Phyc. Bor.-Am. Fasc. i. no. 3. 1895. Collins. The Algae of 

 Jamaica. Proc. Am. Acad. Arts Sci. 37: 239. 1901. Tilden. American 



Algae. Cent. VI. no. 589. 1902. Setchell and Gardner. Algae of North- 

 western America. Univ. Calif. Pub. Bot. i: 185. 1903. Collins. The Algae 

 of the Flume. Rhodora. 6: 230. 1904; Phycological Notes of the late Isaac 

 Holden. — II. Rhodora. 7: 236, 243. 1905. Tilden. American Algae. Cent. 

 VII. Fasc. I. no. 640, 641. 1909. 



Plate V. fig. 1-4. 



Plant mass thick, compact, or sometimes forming penicillate or branched 

 tufts, attached at base, upper portions floating, bright blue-green or dark 

 lead color; filaments more or less straight, fragile, entangled; sheaths thin, 

 fragile, usually soon diffluent into an amorphous mucus; trichomes 4.5-12 

 mic. in diameter, usually not constricted at joints, rarely somewhat monili- 



