vol.i] Setch ell-Gardner. — Algcs of Northwestern America. 191 



Nostoc sphasricum Vaucher. 



On dripping rocks among mosses. Amaknak Island, Bay of 

 Unalaska, Alaska. W.A.8- and A.A.L., No. 3291? 



The habit and arrangement of the triehomes of this specimen 

 resemble the original description and figures. The triehomes 

 are 5.5-6 /«• in diameter, which is large for this species. There 

 are no spores. 



Nostoc minutum Desmazieres. 



On dripping rocks, much mixed with other alga? of a gela- 

 tinous nature. IUuliuk, Unalaska, Alaska, W.A.8. and A.A.L., 

 No. 4032? 



The thalli are minute and spherical. The triehomes are 

 densely intertwined, and measure 3 }>■ or less. The periderm is 

 firm. There are no spores. 



Nostoc microscopicum Carmichael. 



Floating, intermingled with other alga?. Whidbey Island, 

 Wash.. X.L.G.. No. 612?; Seattle, Wash., N.L.G., Nos. 352!, 

 562!. 581! 



Nostoc sphaeroides Kuetzing. 



Forming a soft bluish green coating on rocks. Juneau, 

 Alaska. Saunders. No. 75? (1901. p. 398). 



Nostoc caeruleum Lyngbye. 



In a ditch of fresh water. Near Seattle, Wash., N.L.G., 

 No. 586? 



Seems to belong here, but most of the specimens have passed 

 maturity. 



Nostoc pruniforme (L.) Agardh. 



In ditches of fresh water. Near Seattle, Wash., N.L.G., 

 Nos. 374!. 375! 



Nostoc verrucosum (L.) Vaucher? 



Fresh water pools at Port Clarence, Alaska, Harvey (1872, 

 p. 463.) 



Anabaena variabilis Kuetzing. 



In ditches and ponds. Whidbey Island, Wash., A. £.<?., No. 

 573!: Seattle, Wash., X.L.G., Nos. 588!, 607! 



