64 University of California Puhlications in Botany [Vol.8 



long; protoplaist with a few large, scattered, refriiigent granules; 

 dissepiments conspicuous, non-granular, apical cell convex, calyptra 

 none. 



Growing among other species of OscHlatorin in a salt water pond, 

 B street, Oakland, California. 



Meneghini, Consp. Algol. Eugan., 1837, p. 9 ; Gomont, Monogr. des 

 Oseill., 1892, p. 222 (1893, p. 242, Repr.). 



The type specimens of 0. geniinata were from the thermal waters 

 of the Euganean springs, and what seems to be the same species or, 

 at least, very close to it, occurs also in thermal waters in the Yellow- 

 stone National Park. The brackish water specimens referred here 

 have the cells short, yet within the proportions given. Otherwise they 

 seem typical. They were mixed with Oscillatoria hrevis var. neapoli- 

 tana (Kuetz.) Gomont. 



Section 4. Attenuatae Gomont 



Trichomes decidedly attenuate above, more or less acutely uncinate 

 or flexuous, not definitely spiral (0. chalyhea at times excepted) ; 

 cells longer or shorter than the diameter, never very short; plants 

 commonly slender, not over 13/i, thick, inhabitants of fresh and thermal, 

 more rarely of saline waters. 



Gomont, Monogr. des Oscillar., 1892, p. 203 (1893, p. 223, Repr.). 



8. 0. laeteviretis (Crouan) Gomont 



9. 0. acuminata Gomont 



10. 0. hrevis Kuetz. 



11. 0. Okeni (Ag.) Gomont 



12. 0. chalyhea (Mert.) Gomont 



8. Oscillatoria laetevirens (Crouan) Gomont 



Trichomes associated into a delicate membrane of deep blue-green 

 color, the single filaments being of a yellow-green color, straight, deli- 

 cate, slightly constricted at the dissepiments, 3-5ju. diam. ; apices 

 straight or uncinate, with the terminal cells obtuse or subacute ; cells 

 2.b-bjx long; protoplasm with fine, evenly dLstributed granules. 



Growing in salt marsh pools. San Francisco Bay, California. 



Gomont, Monogr. des Oseill., 1892, p. 226, pi. 7, fig. 11 (1893, 

 p. 246, Repr.). Oscillatoria laetevirens Crouan, Liste des algues 

 marines Finistere, 1860, p. 371 (nomen nudum), Fl. du Finist., 1867, 

 p. 112 (descr.). 



