1919] Setchell-Gardncr : Myxophyceae 57 



ness of the spiral ; and (4) by the regularity or irregularity of the 

 spiral. Usuallx' tlif Iriclionu-s show decided uniformity within the 

 species, but occasionally certain trichomes are found showing varia- 

 tion of a profound and jierplexing character. Spirulina major, for 

 example, is usiiallx- to be distinguished from Sp. Mcneghiiimna Zanard., 

 which approaches it closely in dimensions, by its regular spiral, which 

 is, however, lax in both species. From Sp. suhsalsa CErst., Sp. viajor 

 is to be distinguished by its lax spiral, which is tight in Sp. suhsalsa. 

 A specimen from the warm salt waters of the Key Route pool in 

 Oakland (Gardner, no. 3237) shows tightly coiled and regular loosely 

 coiled turns in the same trichome, seemingly being partly Sp. major 

 and partly Sp. suhsalsa. Such specimens throw doubt on the usual 

 criteria of species. 



2. Spirulina subsalsa f. oceanica (Crouan) Gomont 



Trichomes forming a thin blue-green or yellowish green stratum 

 on mud, or floating among other algae, 1/x diam., twisted into a nearly 

 straight, regular, tightly coiled spiral. 



Growing in pools of brackish water. AVhidbey Island, Washing- 

 ton, and San Francisco Bay, California. 



Gomont, Monogr. des Oscill., 1892, p. 254, pi. 7, fig. 32 (1893, 

 p. 274, Repr.) ; Setchell and Gardner, Alg. N.W. Amer., 1903, p. 182; 

 Collins, Holden, and Setchell, Phyc. Bor.-Amer. (Exsicc), no. 954. 

 Oscillaria oceanica Crouan, Algues marines du Finistere, no. 324 

 (in part). 



The smaller form of the species is the onl}^ one" which has occurred 

 to us in our territory, but seems typical and is probably widespread 

 in shallow pools of brackish water. 



SUBFAMILY 2. OSCILLATOEIEAE forti 



Trichomes always simple, straight or at times in a loose more or 

 less regular but not especially distinct spiral, destitute of a distinct 

 sheath. 



Forti, in De-Toni, Syll. Alg., vol. 5, 1907, p. 147. 



"We have followed Forti in the name and limits of this subfamily. 

 It is decidedly more restricted than the subtribe Oscillarioideae of 

 Gomont (1892, p. 95, 1893; p. 115, Repr.). 



