Manchester Memoirs, Vol. liii. (1909), No. 14. 7 



so far only been found in Guiana. The only species 

 recorded in Europe, is C. Corinaldi Menegh., which was 

 once found near Pisa, but has apparently now dis- 

 appeared.* 



On our last two visits to the Reddish Canal, we were 

 much interested to find patches of Vallistieria spiralis 

 with its characteristic female flowers. This plant we had 

 not observed before, possibly owing to the likeness of its 

 leaves to those of young submerged plants of Alisina, 

 which are common along the banks of the canal. I am 

 told by Mr. Hardy, of the Manchester Museum, that the 

 Vallisneria was planted in the canal nearly 40 years ago. 

 Though planted between the swing bridge and the 

 mill (that is, near station 9), it has spread now along the 

 canal, and has established itself in several patches, all of 

 which are in the warmest regions of the canal. Thus one 

 clump was found near Broadstone Mill (station 4) to east 

 of the inflow from that mill, and one to the west of the 

 inflow (station 5). Two other patches occurred near the 

 inflow from Reddish Mill (station 6 and 7), and a fifth 

 and sixth ones at stations 12 and 13, that is, close to the 

 inflow from the furthest mill. The temperature of the 

 canal varied on the occasion of our last visit, from 39° to 

 76°F. at various points, and Vallisneria grew in water 

 which, for the most part was over 70°F. It will be seen, 

 therefore, that this plant has selected definite positions 

 apparently, according to the warmth of the water. 



In concluding we should like to acknowledge the help 

 received from Mr. T. G, Osborn and Mr. W. Brierley in 

 our preliminary survey of the alien vegetation of the 

 Reddish Canal, which we hope to follow up more closely. 

 At present we may say that the aliens so far noted, have 



* De Toni J. B. " Sylloge Algarum." Patavia. 1889-1907. 



