460 Wisconsin Academy of Sciences , Arts , and Letters. 
Italy (Gugliemetti, 1910; Lemmermann, 1908G). Scotland (West 
and West, 1905). Switzerland (Chodat, 1902). 
AFRICA. Azores (Bohlin, 1902). Lake Albert Nyanza (G. S. 
West, 1909C). Lake Nyassa (G. S. West, 1907). Lake Tanganyika 
(G. S. West, 1907). 
ASIA AND OCEANIA. Burma (West and West, 1907). 
Ceylon (Lemmermann, 1907A). Siam (West and West, 1902). 
AMERICAS. Brazil (Bohlin, 1897; Lemmermann, 1910A). 
Paraguay (Bohlin, 1897; Lemmermann, 1910A). United States 
(Borge, 1909; Snow, 1903). 
17. S. armatus (Chodat) nov. comb. PI. XXVIII: Fig. 
53, PI. XXIX: Figs. 90-93. PI. XXX: Figs. 109-110.) 
S. hystrix ysly. armatus. Chodat, 1902, p. 215; Fig. 140. Heering 
und Homfeld, 1904, p. 83. Reinhardt, 1905, p. 26. Migula, 1907, 
p. 657. Bernard, 1909, p. 78; PI. VI, Figs. 171-175. Chodat, 
1913, p. 24. 
S. quadricauda var. acutiformis. Schmidle, 1900A, p. (111). 
S. brasiliensis quadricauda. Volk, 1903, p. 103. 
S. hystrix forma armatus. Volk, 1905, p. 64. Selk, 1907, pp. 
7, 57, 64, 68, 73, 79, 85, 91, 94, 99, 103, 108, 115. 
S', hystrix forma armatus abundans. Volk, 1905, p. 64. Selk. 
1907, pp. 57, 68, 73, 79, 85, 91, 99. 
S. hystrix forma armatus bicaudatus. Volk, 1905, p. 64. 
S. hystrix forma armatus cohaerens. Volk, 1905, p. 64. Selk, 
1907, p. 6. 
S. hystrix forma armatus setosus. Volk, 1905, p. 65. 
S. hystrix var. armatus forma depauperata. Wille, 1913, p. 146. 
Cellulis 2-8 in seriem rectam vel subalternantibus dis- 
positis, cellulis ovatis vel oblongi-ovatis, utroque polo cellulis 
terminalibus rotundatis cum uno aculeo, polo cellulis in- 
terioribus coenobius rotundatis sine aculeis. Membrana cel- 
lularum longitudinaliter costata in utroque parte. 
Dimens. cell. 7x4, 9x4, 9x4.5, 11x4, 11x6, 12x8, 
14 x 7 ju. Long. acul. 5.5-7 p. 
Previous to the beginning of the cultural work I had fre¬ 
quently observed in field material that lateral ridges ap¬ 
peared on four-celled coenobia which also bore a spine at 
each corner, but thought it was merely a passing condition 
in certain cells of S. quadricauda (Turp.) de Breb. The isola¬ 
tion of several strains in which this lateral ridge constantly 
appears in all of the colonies, along with the four spines, has 
shown this to be a constant character warranting raising 
the variety armatus to specific rank. 
