Freshwater Mussels pay 
STUDIES OF THE BIOLOGY OF FRESHWATER MUSSELS. 
III. DISTRIBUTION AND MOVEMENTS OF WINONA LAKE 
MUSSELS.! 
WILLIAM RAY ALLEN. 
INTRODUCTION. 
Many summers have been more or less devoted to the study of lake 
Unionidae by the writer. An account of the feeding mechanism and 
survey of the food materials was published in 1914. A further study of 
ingestion, food selection and digestion by experimental methods appeared 
in 1921. While attempting to account for the assortment of food ma- 
terial, further study was made of the distribution and effectiveness of 
the organs of special sense. A paper on reactions to chemical and phys- 
ical stimuli is now ready for the press. Some of the statements which 
are made in the following pages, e. g. reactions to light and pressure 
sense, are based upon data fully discussed in the above paper and may 
here seem arbitrary. To what extent the animals assume a definite place 
in the lake in response to these physical and chemical stimuli, it is the 
province of the present paper to show. 
Previous Survey. Headlee and Simonton’s careful exploration of 
the mussels of Winona Lake (’03) revealed eight species—Lampsilis 
luteolus, L. subrostratus, L. glans, Micromya fabalis, Quadrula rubigin- 
osa, Anodonta grandis, A. edentula and Margaritana marginata. I have 
translated from the synonymy of Call (’99) to that of Simpson (’99). 
In many summers’ collecting I have added but one species and only a 
single specimen—Quadrula plicata, 175 mm. in length, taken off Yar- 
nell’s Point. It is a river form, and having no direct access from the 
outlet on account of the dam, it probably owes its introduction to an 
accidental fish host or to human agency. 
Headlee and Simonton state that Lampsilis luteolus and Anodonta 
grandis greatly outnumber the other species. They show that the 
mussel zone lies upon or near sandy and gravelly banks; that distribu- 
tion toward the shore is limited by waves and muskrats, and outward by 
the soft character of the bottom. Furthermore. they believe that the 
“black marl” of. the deeper water destroys any mussels which go too 
far out by stopping up the gills. 
The Anodontae were found by Headlee and Simonton in the edge 
of banks where sand and mud intergrade, edentula being more of a 
mud-dweller than grandis. Lampsilis luteolus was found to be the most 
cosmopolitan, found principally upon sand and gravel. Fabalis and 
glans occurred in deeper water, on relatively firm bottom. Subrostratus 
inhabited the outer portion of the range of luteolus. 
1 Contribution from the Zodlogical Laboratory of Indiana University No. 188. 
