Vol.:] Sefchfll-Gdnhier. — Alg(e of Northivesiern America. 191 



Nostoc sphaericum Vaucher. 



On dripping' rocks among mosses. Amakuak Island, Bay of 

 Unalaska, Alaska, W.A.S- ami A. A. L., No. 3291? 



The habit and arrangement of the trichomes of this specimen 

 resemble the original description and figures. The trichomes 

 are 5.5-G h^ in diameter, which is large for this species. There 

 are no spores. 



Nostoc minutum Desmazieres. 



On dripping rocks, mnch mixed with other algje of a gela- 

 tinous nature. Iliuliuk, Unalaska, Alaska, ir.A.*S. and A.A.L., 

 No. 4032 f 



The thalli are minute and spherical. The trichomes are 

 densely intertwined, and measure 3 /a or less. The periderm is 

 firm. There are no spores. 



Nostoc microscopicum Oarmichael. 



Floating, intermingled with other algw. Whidbey Island, 

 Wash., N.L.G., No. ()12?; Seattle, Wash., N.L.G., Nos. 352!, 

 562!, 581! 



Nostoc sphaeroides Kuetzing. 



Forming a soft l)luish 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, l)ut most of the specimens have passed 

 maturity. 



Nostoc pruniforme (L.) Agardh. 



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

 Nos. 374!, 375! 



Nostoc verrucosum (L.) Vaucher? 



Fresh water pools at Port Clarence, Alaska, Ildnui/ (1872, 

 p. 463.) 



Anabaena variabilis Kuetzing. 



In ditches and ponds. Whidbey Island, Wa.sh.,A./>.C/., No. 

 573!; Seattle, Wash., N.L.G., Nos. 588!, 607! 



