408 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



(Vol. 10 



Odessa, I; Lake P. 



The specimens were rather smaller than usual, but were other- 

 wise typical. 



Var. arcuatum (Br6b.) Ehrenb. 



Outer margin 150° of arc; length 150-164 n; breadth 17-18 p. 

 Lake Etta; Lake P. 



CI. eboracense Turn. ( = St. cucumis Wolle, Desm. United 

 States, pi. 7, /. 17, 18. 1892). PL 21, fig. 9. 



Outer margin 100-110° of arc; length 240-250 n; breadth 

 40-43.5 n. 



North Twin Lake, near Wing. 



The specimens agreed very well with the figures and dimensions 

 given by Wolle, although they are considerably larger than 

 British examples according to West, Brit. Desm. 1 : 140. pi. 16, 

 f. 7, 8. A striking peculiarity is the frequent sigmoid form of 

 the cells, nearly every cell being twisted so that the true curvature 

 is very difficult to obtain. As far as could be ascertained the 

 only species hitherto known which possesses sigmoid cells is CI. 

 sigmoideum Nordst. & Lagerh. (West, Brit. Desm. 1: 153. pi. 

 19, f. 1-4), but this species is very much more slender than the 

 present specimens which, except for this peculiarity, are typical 

 examples of CI. eboracense Turn. 



CI. lanceolatum Kutz. 



Outer margin 32-42° of arc; length 365-500 [l; breadth 50-62 v.. 



Odessa, H; Odessa, I; Eastgate's Pond. 



CI. Leibleinii Kutz. 



Outer margin 120-150° of arc; length 100-135 |*; breadth 

 15-18 [x. 



Odessa, I; North Twin Lake, near Wing. 



The specimens were not exactly typical, since there was only a 

 slight and often scarcely perceptible median swelling instead of 

 the pronounced one usually present. They seemed in many 

 ways intermediate in form between CI. Leibleinii and CI. Dianae, 

 but they were certainly too stout to be referred to any form of 

 the latter. 



