398 Canadian Record of Science 



with Myriophyllum. A small streamlet of water 

 which flowed down a steep bank into this pond 

 was filled with almost a pure mass of Ulothrix. On the 

 brick flags of the floor of the conservatory, I noticed a 

 thin blackish green scum which proved to be a mixture 

 of Calothrix, Tolypothrix, Scenodesmus and Lyngbya. 

 The metal horse-trough on the driveway contained 

 Ulothrix, some filaments of Spirogyra and Zygnema, and 

 a good many Palmellaceae. 



(4) Back River: 



The Riviere des Prairies, which is also known as 

 Back River, is very shallow in some places, especially at 

 Sault au Recollet. Here, along the edge of the water, 

 Elodea was very plentiful. Entangled with this was a 

 great deal of Hydrodictyon, Spirogyra and Zygnema. 

 Later on, in the winter, Mougeotia developed in the 

 aquaria in which these collections were placed. Clado- 

 phora also occurred here, showing its preference for 

 running water. A small brook emptying into the river 

 contained an enormous amount of Spirogyra, Vaucheria, 

 CEdogonium and Zygnema growing together attached 

 to stones on the bottom. The Spirogyra was very 

 luxuriant and dark green in color. 



( 5 ) Bout de l 'Ile : 



This is the extreme eastern end of the island, where 

 the Riviere des Prairies and the St. Lawrence join. Both 

 rivers are very deep at this point and flow swiftly, con- 

 sequently algal growth is scanty. Along the edge of the 

 Riviere des Prairies, Stigeoclonium was abundant on the 

 Leda clay, which always appears to be a favourable sub- 

 stratum for it. All along the edge of the St. Lawrence 

 great mats of Vaucheria and Microspora were found 

 having evidently been brought down by the current 

 and caught in tufts of Elodea. Nearly all were 



