Myxophyceae 179 



an interesting form of Nostoc. It was first observed in 1864 by Professor 

 Oliver Marcy. Thrown out upon the shore by the waves, it appears as 

 small, purple and green balls or thalli." (Atwell). Thrown up in extensive 

 "windrows" on the shore of Lake Michigan. Evanston. August 1894. (John- 

 son). Minnesota. Lake Kilpatrick. June 1893; floating free or attached 

 to water plants in artificial lake, Minneapolis, August 1894. (Tilden). Iowa. 

 Nodules often reaching the size of a plum. (Fink). Very small, in pool 

 near Ontario, Ames. (Buchanan). Nebraska. In still water. (Saunders). 

 Idaho. (Twitchell). Washington. In ditches of fresh water. Near Seattle. 

 (Gardner). 



336. Nostoc verrucosum (Linn.) Vaucher. Histoire des Conferves d'eau 

 douce. 225. pi. 16. f. 3. 1803. Bornet and Flahault. Revis. des 

 Nostoc. Ann. Sci. Nat. Bot. VII. 7: 216. 1888. De Toni. Syll. Algar. 

 S: 419- 1907. 

 Harvey. Nereis Boreali-Americana. Part III. 114. 1858. Dickie. Al- 

 gae. Hooker. An Account of the Plants collected by Dr. Walker in Green- 

 land and Arctic America during the expedition of Sir Francis M'Clintock, 

 R. N., in the Yacht "Fox," 21 Je. i860. Journ. Linn. Soc. Bot. S: 79. 1861; 

 Notes on a Collection of Algae procured in Cumberland Sound by Mr. 

 James Taylor. 1. c. 9: 241. 1867. Harvey. Determinations of Algae in 

 Rothrock's Sketch of the Flora of Alaska. Ann. Rept. Bd. Regents. Smiths. 

 Inst, for 1867. Wood. Contr. Hist. Fresh-Water Algae North America. 

 28. 1874. WoUe. Fresh-Water Algae. U. S. 284. pi. 197. f. i, 2. 1887. 

 Johnson and Atwell. Fresh Water Algae. Northwestern University. Report. 

 Dept. Nat. Hist. 21. 1890. Anderson and Kelsey. Common and Conspicu- 

 ous Algae of Montana. Bull. Torr, Bot. Club. 18: 144. 1891. Millspaugh. 

 Contribution III. to the Coastal and Plain Flora of Yucatan. Field Colum- 

 bian Museum. Bot. i : 347. 1898. Tilden. American Algae. Cent. V. no. 

 393. 1900. Bessey, Pound and Clements. Additions to the Reported Flora 

 of the State. Bot. Surv. Nebraska. 5: 12. 1901. Collins. The Algae of 

 Jamaica. Proc. Am. Acad. Arts Sci. 37: 240. 1901. Tilden. Collection of 

 Algae from the Hawaiian Islands. Haw. Almanac and Annual for 1902. 112. 

 1901; American Algae. Cent. V. no. 487. 1901; Cent. VI. no. 583. 1902; Algae 

 Collecting in the Hawaiian Islands. Postelsia: The Year Book of the 

 Minnesota Seaside Station, i: 170. 1902. Setchell and Gardner. Algae 

 of Northwestern America. Univ. Calif. Pub. Bot. i: 191. 1903. Brown. 

 Algal Periodicity in Certain Ponds and Streams. Bull. Torr. Bot. Club. 

 35: 242, 247. 1908. 



Plate VIII. fig. 11-16. 

 Colonies often gregarious, up to 10 cm. in diameter, at first solid, 

 gelatinous, firm, spherical or rotund and plicate-undulate, afterwards be- 

 coming hollow, vesicular, softer, and torn, when young olive-blackish, be- 

 coming brownish green when older; filaments flexuously twisted, densely 

 entangled near the surface; sheaths thick, often indistinct, colorless or 

 yellowish brown; trichomas 3-3.5 mic. in diameter, especially cylindrical; 

 cells spherical depressed, shorter than the diameter; closely connected; 

 heterocysts 6 mic. in diameter, somewhat spherical; gonidia 5 mic. in 

 diameter, 7 mic. in length; oval; wall of gonidium smooth, yellowish. 



