Myxophyceae 197 



Fasc. 23. no. 1107. 1903. Nelson. Observations upon some Algae which 

 cause "Water Bloom." Minn. Bot. Studies. 3: 53. pi. 14. f. i. 1903. Riddle. 

 Brush Lake Algae. Ohio Nat. 5: 268. 1905. Collins, Holden and Setchell. 

 Phyc. Bor.-Am. Fasc. 28. no. 1359. 1907. 



Plate X. fig. I. 



Colonies small, aggregated in membranaceous flakes, fragile, blue-green; 

 trichomes 5-6 mic. in diameter, rigid, tapering at the ends; cells somewhat 

 quadrate, 5-15 mic. in length; heterocysts 6-7 mic. in diameter, 15-20 mic. 

 in length, somewhat cylindrical; gonidia 7-8 mic. in diameter, 60-80 mic. in 

 length, cylindrical, elongate, containing granular protoplasm; wall of go- 

 nidium smooth, colorless. 



Massachusetts. Floating on quiet water. Medford. October 1906. (Lam- 

 bert). Ohio. Sandusky Bay; Brush Lake. (Riddle). Plankton. Put-in-Bay, 

 Lake Erie. (Snow). Minnesota. Lake Tetonka, Waterville. 1882. (Ar- 

 thur). Lake of the Woods. July 1894. (MacMillan). Lake Minnetonka. 

 189S. (Crocker). On surface of water around edges in quiet bays during 

 summer and early autumn. Long Lake, Hennepin County. September 1895. 

 (Shaver and Tilden). In a shallow lake in the depressions of the Fergus 

 Falls moraine, Fergus Falls. August 1900. (Ballard). California. Floating 

 on Lake Chabot, San Leandro. June 1902. (Gardner). 



Genus CYLINDROSPERMUM Kuetzing. Phyc. Gen. 211. 1843. 



Plant mass expanded, indefinite, mucous; sheaths not present; trich- 

 omes equal, short, embedded in an amorphous mucus; cells cylindrical, 

 longer than their diameter; heterocysts terminal, solitary; gonidia devel- 

 oped from the cell or cells next the heterocyst, generally solitary, rarely 

 seriate. 



I Gonidia solitary. 



1 Gonidia cylindrical, up to 40 mic. in length 



(i) Gonidia 10-16 mic. in diameter, 32-40 mic. in length 



C. stagnale 



(2) Gonidia 11-12 mic. in diameter, 23-24 mic. in length 



1 C comatum 



2 Gonidia oblong or ventricose-elliptical 

 (i) Wall of gonidium punctate 



A Gonidia 10-15 mic. in diameter, 20-38 mic. in length, ventricose- 

 elliptical; wall of mature gonidium rough, punctate 



C. ma jus 



B Gonidia 6-6.5 mic. in diameter, 16-19 inic. in length, elliptical; 

 wall of gonidium very finely granular C. minutum 

 (2) Wall of gonidium smooth 

 A Gonidia 8-9 mic. in diameter, 18-20 mic. in length 



C. minutissimum 

 B Gonidia 9-12 mic. in diameter, 18-20 mic. in length 



C. muscicola 



