1923] 



MOORE AND CARTER — ALGAE FROM NORTH DAKOTA LAKES 409 



Genus cosmarium Corda 



Cosmarium formosulum HofT. 



Cut-off Pond, south end of Stump Lake; Lake P; Odessa, I; 

 Eastgate's Pond. 



Var. Nathorstii (Boldt) W. & G. S. West. 



Cut-off Pond, south end of Stump Lake. 



C. granatum Breb. 



Lake P; Odessa, I. 



C. scopulorum Borge in Arkiv f. Bot. 18 10 : 12. pi. 1, f. 11^. 

 1923. 



* 



Cut-off Pond, south end of Stump Lake; Lake P; Lake Isabelle. 

 C. hians Borge in Bot. Not. 1913: 13. pi. l,f. 6. 1913. 

 Length 19-21 [x; breadth 19-21 [x; isthmus 7-7.5 \i. 



Odessa, I ; Cut-off Pond, Stump Lake. 



The specimens were slightly smaller than the original ones 

 of Borge, but were otherwise exactly similar. The species has 

 previously been recorded only from Sweden. 



C. impressulum Elfv. 



Eastgate's Pond. 



C. Meneghinii Br£b. 



Odessa, I. 



C. pygmaeum Arch. 



Cut-off Pond, Stump Lake; Eastgate's Pond. 



A form with the end view elliptical and only one protuberance 

 in the center of each lateral margin, the smaller ones on either 

 side being absent. 



C. Regnellii Wille. 



Rare in Eastgate's Pond. 



C. subcostatum Nordst. forma minor W. & G. S. West ( = C. 

 calcareum Johnson in Bull. Torr. Bot. Club 21: pi. 211, f. 13. 

 1894). 



Cut-off Pond, Stump Lake; Lake P; Odessa, I; Eastgate's 



Pond; Wheeler's Pond; Dion Lake; North Twin Lake, near Wing. 

 C. tenue Arch. 



Cut-off Pond, Stump Lake. 



C. Turpinii Br6b. var. podolicum Gutw. 



Eastgate's Pond. 



Johnson has recorded this form from Louisiana. 



