Fresh Water Algae in Vicinity of Montreal 421 



Family 3. Naviculaceas. 

 Navicula sp? 



Family 4. Gomphonemaceae. 

 Gomphonema geminatum. 

 On filaments of Mougeotia. 



G. eonstrictum. 



On filaments of Mougeotia. 



III. Cyanophyceae. 



Order I. Hormogoneales. 

 Family 1. Scytonemaceae. 

 Tolypothrix trunciola, Rab. 



Diam. of filaments 11-14 mier. 



Dull aeruginous, articulatious % as long as broad. 

 Heterocysts subsperical, singly at the base of the 

 branches, making a velvety black, fuscous sur- 

 face. 

 Mount Royal. 



Family 2. Nostocaceae. 



Nostoc Sp? 

 Verdun. 



Anabaena oscillarioides, Bory. 



Forming bluish-green stratum. Triehomes elon- 

 gated, joints sub-quadrate, distinct, heterocysts 

 barrel shaped. Cells 4-5 x 4-6 micr. Hetero- 

 cysts 6-8 x 7-9 micr. Spores 7-8 x 8-12 microns. 



Bout de Tile. 



