170 KAARE MÜNSTER STRØM. 



119. Micrasterias denticulata. Breb. 



This species occurred in a sample between the filaments of 

 Mougeotia parvula, Zygnema and Spirogyra. The specimens 

 were mostly resembling the var. angusto-sinuata Gay but also 

 the var. angulosa (Hantzsch.) W. & G. S. West, differing from 

 the former in having the subdivision of the lobes, from the 

 latter in having the incisions closed and very narrow, from 

 them both in having much shorter apical incisions. The cell- 

 wall was punctate. Size: long. 280 /n, lat. 212,«, lat. isthm. 34,5,«. 

 PL III, Fig. 9. 



Genus Cosmarium. Corda 1834. 



120. Cosmarium Ralfsii. Breb. 



Rare, I have only observed this species from a single 

 locality. 



121. Cosmarium undulatum. Corda. 



General, and often in abundance. Size: long. 53 f^i, lat. 37,&|«, 

 lat. isthm. 15 fi. 



122. Cosmarium subundulatum. Wille. 

 Somewhat rare. 



123. Cosmarium Cucumis. (Corda) Ralfs. 

 Somewhat scarce. 



124. Cosmarium Phaseolus. Breb. 



General, and often in quantity. Size : long. 27 «, lat. 27,5 jtf. 



124 a. var. elevatum. Nordst. 



Not so common as the principal form. I have probably 

 determined many of the specimens of which I have not seen the 

 vertical view to be C. subtumidum. 



125. Cosmarium tumidum. Lund. 



Not uncommon, and sometimes in quantity. Size: long. 35 jt/, 

 lat 27,5 /il, lat. isthm. 8,5 a. 



126. Cosmarium bioculatum. Breb. 

 Fairly general, but never in quantity. 



