Lake Maxinkuckee, Physical and Biological Survey 143 



11. RIVULARIA DURA Roth 



Not a plankton-alga ; obtained from hand-gathered material. 

 The following is a note on the Weedpatch vegetation, August 28, 

 1900 : "All these plants are covered thickly with Rivularia, some 

 in quite large colonies. It was also found on Chara, collected the 

 same date. On September 12 (1900) sticks in Lost Lake were 

 thickly covered with globular brownish-black beads of Rivularia 

 and bright green beads of Chsetophora. A good deal of Rivularia 

 was noted, attached to Potamogetons at McSheehy's pier, Septem- 

 ber 20. 



Rivularia is one of the most abundant algse in the lake, thickly 

 dotting stems and leaves of water-plants with brown or blue-green 

 hemispherical gelatinous masses about the size of a pinhead or 

 somewhat larger. It is, indeed, at times difficult to find an example 

 of water plant in the lake which is not more or less thickly dotted 

 with these colonies. It is found the year round, but is probably 

 more abundant in summer. It is never found free-floating in the 

 lake. It is probable that fishes sometimes nibble it off the leaves, 

 especially off the Chara where it stands out in bold relief. In the 

 collections it appears associated with (Edogonium, Bulbochaete, 

 Oscillatoria, etc. 



12. RIVULARIA HAEMATILES Agardh 



Like the other species, this is not a plankton alga ; it is probably 

 not common, and was obtained on only two occasions, once Septem- 

 ber 12, and again on September 29, 1900. We have no notes con- 

 cerning it except the records of its occurrence. 



13. CALOTHRIX FUSCA B. & F. 



Not a plankton alga but obtained by hand-gathering along with 

 Chaetophora, Cladophora, etc., and various desmids. Fairly com- 

 mon and well distributed near shore. 



14. SPIRULINA JENNERI Kuetzing 



Very common in a red, gelatinous coating on west shore by 

 Chadwick's, August 13, 1906, with Anahaena stagnalis and Proto- 

 coccus. The exceedingly slender filaments have a peculiar spiral 

 appearance. 



15. OSCILLATORIA TENUIS Ag. 



Not common ; obtained in one of the vertical plankton hauls and 

 represented in four other collections. It was probably more com- 

 mon in the neighborhood of Norris Inlet. Floating, black, slimy 

 masses, composed of Oscillatoria, may occur now and then in the 

 lake, one such being observed September 12, 1900. 



