138 WILLIAM RAY ALLEX. 



not refuse minute dead animals or small fragments of sloughed 

 and decaying animal tissue. In many cases bits of material 

 seemingly the carapaces of small Crustacea are found to resist 

 digestion throughout the alimentary canal. However most of 

 the animal matter consists of shapeless unidentifiable fragments. 



In order to determine the ability of mussels to capture and 

 digest living animals, a few were kept without food for several 

 days, then a rich culture of Paramecium was added. This was 

 found to be of sufficient nutrient value to regenerate the crystal- 

 line style in part. The digestive tract was seen to be filled again 

 with half assimilated material. Few living Paramecia were 

 discovered beyond the stomach, thus corroborating Vogt and 

 Jung's statement ('94) that digestion is nearly completed in that 

 organ. 



In the second place, the plant material does not consist so 

 largely of diatoms, there being probably as many other algal 

 forms. Very few desmids were observed, in fact only three 

 genera which I could identify with certainty. But Winona Lake 

 does not produce many desmids, and it is not probable that they 

 are discriminated against where they exist more abundantly. 



The following is a list of genera recognized. There were several 

 more which I could not identify. 



DlATOMACE.K. OTHER 



Amphora Anabcena 



A rachnoidiscus Aphanocapsa 



Cocconeis Ccclastrum 1 



Cocconema Cylindrocapsa 



Coscinodiscus Eudorina 1 



Craspedodiscus Glococystis 



Cymbella Leptothrix 



Epithemia Lyngbya 



Fragilaria Merismopedia 1 



Gomphonema (Edogonium 1 



Melosira Oscillatoria 



Navicula Pandorina 1 



Phurosigma Pediastrum 1 



Surirella Protococcus 



