422 



PROCEEDINGS OF THE ACADEMY OF 



[July, 



Table II — Effect of Myriophyllum. 



Effect of Sediment. — The gizzard of Lymncea columella, like the latter, 

 is usually filled with fine sand. However, in dissecting a number of 

 individuals of Lymmea columella that had been raised in clean battery 

 jars I found no sign of sand. In a few individuals I found some grains, 

 when a dihgent search of the jar failed to reveal any more. It seems 

 that this individual had in its crop the only grains of sediment that the 

 jar contained. 



