94 Minnesota Algae 



185. Phormidium persicinum (Reinke) Gomont. Monogr. Oscill. 184. 1893. 



De Toni. Syll. Algar. 5: 220. 1907. 



Collins. Notes on Algae. — II. Rhodora. i: 11. 1900; Preliminary Lists 

 of New England Plants. — V. Marine Algae. Rhodora. 2: 42. 1900. West. 

 West Indian Freshwater Algae. Journ. of Bot. 42: 292. 1904. Collins, 

 Holden and Setchell. Phyc. Bor.-Am. Fasc. 29. no. 1401. 1907. 



Plant mass a delicate, continuous, velvety, rose-colored coating on 

 marine shells; filaments loosely entangled; sheaths close, diffluent into 

 an amorphous mucus; trichomes 1.7-2 mic. in diameter, especially con- 

 stricted at joints; apex of trichome tapering; apical cell acute conical; 

 calyptra none; cells 2-7 mic. in length; cell contents homogeneous. 



Massachusetts. Forming a thin pink film on shells, mostly on the 

 S p i r o r b i s which is often attached in great abundance to larger algae. 

 Nahant. June 1899. (Collins). In a jar in the Marine Biological Laboratory. 

 Wood's Hole. May 1907. (Davis). West Indies. On roots of mangroves 

 in brackish swamp. Near Bridgetown, Barbados. (Howard). 



186. Phormidium foveolarum (Montagne) Gomont. Monogr. Oscill. 164. 



pi. 4. f. 16. 1893. De Toni. Syll. Algar. 5: 221. 1907. 

 Setchell and Gardner. Algae of Northwestern America. Univ. Calif. 

 Pub. Bot. i: 184. 1903. 



Plate IV. fig. 54. 



Plant mass very thin, orbicular, "nestling" in depressions of cretaceous 

 rocks, dark green; sheaths diffluent into an amorphous, gelatinous mucus; 

 trichomes about 1.5 mic. in diameter, variously twisted, parallel, constricted 

 at joints; apex of trichome not tapering; apical cell rotund; calyptra none; 

 cells .8-2 mic. in length; cell contents not granular, pale blue-green. 



Washington. Mixed with P. autumnalein ditches by the roadside. 

 Pleasant Ridge, near La Conner, Skagit County. (Gardner). 



187. Phormidiimi tinctorium Kuetzing. Tab. Phyc. i: 35. pi. 49. f. 3. 1845- 



1849. Gomont. Monogr. Oscill. 182. pi. 4. f. 11. 1893. De Toni. 

 Syll. Algar. S: 218. 1907. 

 Wolle. Fresh Water Algae. VI. Bull. Torr. Bot. Club. 9: 25. 1882; 

 Fresh-Water Algae U. S. 301. pi. 202. f. 22, 23. 1887. (Lyngbya tinc- 

 toria Kg.) 



Plate IV. fig. SS- 



Plant mass penicillate, elongate, attached at base, waving, gelatinous, 

 dark green, when dried yellowisli purple, coloring paper violet; filaments 

 somewhat straight, collected in fascicles, parallel; sheaths very mucous 

 and diffluent; trichomes 6-8.5 rn'c. in diameter, much constricted at joints; 

 apex of trichome straight, occasionally very gradually tapering; apical cell 

 more or less acute conical or cylindrical conical; calyptra none; cells 5-1 1 

 mic. long; transverse walls not granulated; cells contents finely granular. 



Arizona. In springs. April. (Pringle). 



M. Gomont calls attention to the fact that the trichomes of this 



