96 



The Ohio Journal of Science [Vol. XVI, No. 3, 



Like the last several zones mentioned, it has a bottom rich 

 in humus, while the water ranges from six to twelve inches 

 (1.0 to 3 decimetres) in depth. Typha latifoUa grows here to 

 the practical exclusion of everything else, save for an occasional 

 space which may be called — 



The Spirodela Habitat — These spaces are usually a couple 

 of yards or more (1 to 2 metres) in diameter, and are open 

 areas of water rather closely hedged in by Typha, with occasional 

 straggling plants of Sparganium. The water here is, of course, 

 quiet and usually about three to six inches (.7 to 1.5 decimetres) 

 in depth, richly strewn with colonies of Spirodela polyrhiza and 

 Lemna trisulca, principally the former. 



The Castalia Station 



