1923] 



MOORE AND CARTER — ALGAE PROM NORTH DAKOTA LAKES 403 



? L. contorta Lemm. in G. M. Smith, Wis. Geol. & Nat. Hist. 

 Surv. Bull. 57: 53. pi 7, /. 12, 13. 1920. 



Plankton of Lake Isabelle. 



This minute coiled species resembled greatly Smith's figures 

 of L. contorta except that the filaments were much more slender, 

 being less than 1 p in diameter. L. Rivularianum Gomont is 

 about the same size as the specimens from North Dakota, but in 

 this species the trichomes are constricted at the joints and more- 

 over it is not a plankton species. The diameter of L. contorta 

 is given as 1.5-2 [l. 



? L. Martensiana Menegh. 



Lake 0. 



The alga was present in two samples, but in both cases was 

 very fragmentary. The dimensions and thick sheath suggest 

 that it should be referred to L. Martensiana. 



Family Nostochaceae 



Genus wollea Born, et Flah. 



Wollea saccata (Wolle) Born, et Flah. in Tilden, Minnesota 

 Algae, p. 181. pi 8, f. 21, 22. 1910. 



Wheeler's Pond, I; slough below Wheeler's Pond. 



This is the third locality for this interesting species, the alga 

 having previously been recorded only from New Jersey and from 

 Massachusetts. 



Genus nodularia Mertens 



Nodularia spumigena Mertens var. genuina Born, et Flah. 



Stump Lake; East Lake; Creel Bay, Devils Lake; Lake A; 

 Strawberry Lake; inlet of Lake A; North Washington Lake; 

 Mission Bay, Devils Lake; Lamoreau Lake. 



Var. major (Kiitz.) Born, et Flah. 



Lamoreau Lake. 



Genus anabaena Bory 



? Anabaena afiinis Lemm. 



Diam. trich. 5 [i; heterocysts spherical, 7 n in diameter 



Slough below Wheeler's Pond. 



