406 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



Genus rivularia Roth. 



Rivularia coadunata (Sommerfelt) Foslie in Tilden, Minn. 

 Alg. p. 291. pi 20, f. 16, 17. 1910. 



Cut-off Pond, Stump Lake: associated with Chondrocystis 



Schauinslandii. 



R. nitida Ag. 



Dion Lake. 



Genus gloeotrichia Ag. 



Gloeotrichia echinulata (Smith) Richter in G. M. Smith, Wis. 

 Geol. & Nat. Hist. Surv. Bull. 57: 63. pi 11, f. 5, 6. 1920. 



Lake Metigosche; Strawberry Lake; Crow Lake; Carpenter 

 Lake; Fish Lake. 



Family Glaucophyceae 



Genus asterocystis Gobi 1 



Asterocystis smaragdina (Reinsch) Forti in De Toni, Syll. 

 Alg. 5: 691. 1907 (Callonema smaragdina Reinsch, Contr. Alg. 

 Fung. p. 41. pi 16. 1875). PI. 21, figs. 6-8. 



Gordon Lake; Dion Lake; Lake Isabelle; Ensign Lake. 



The figures of Reinsch illustrate an alga growing epiphytically 

 on Cladophora with lax and almost dichotomous branching. 

 The North Dakota specimens occurred in 4 different collections, 

 3 of which were plankton hauls. Only in two of the samples 

 were the specimens at all frequent, and in one of these they 

 were exclusively very young plants growing epiphytically. In 

 the other three cases the specimens were distinctly free-floating. 

 The young plants mentioned above consisted merely of short 

 unbranched filaments, but in the better-developed and free- 

 floating individuals, branching was usually very profuse (pi. 

 21, fig. 6). The lax branching figured by Reinsch was observed 

 in only one individual, and in all others the branching was so 

 intricate that the polarity of the plant could only be traced with 

 great difficulty. 



1 The arrangement of De Toni (Vol. 5. 1907) has been followed in placing this 

 problematical genus in the Myxophyceae. It is, of course, possible that its affinities 

 are more with the Banyiales. 



