f 



173 



Ecological Notes on the Mussels of Winona Lake.* 



i 



By T. J. Headlee and Jajees Simonton. 



In the summer of 1903 the writers, under the direction of C. H, 

 Eigenmami, made observations on tlie mussel distribution of Winona 

 Lalve with ti view to determining the reason for the same. We examined 

 the shore line fi-om 4 inches to 4 feet by wading, from 4 to 7 with 

 a clam rate, fi-om 7 to 86 feet with an iron dredge. 



The species found were determined by comparison with shells that 

 had been named by Call, Simpson and Balder. The nomenclature i& 

 that used by Call in his report on Indiana Mollusca, Geological Report, 

 1899, They were: Unio luteolus. Unio subrostratus, Unio glans, Unio" 

 fabalis. Unio rubiginosus. Anodouta grandis, Anodonta edentnia Mar- 

 garWana marginata. 



This is a deep kettle-hole lake. In general the beaches are composed 

 of sand and gravel, which shade off with varying rapidity into marly 

 sand, tlien into sandy marl, then into coarse white marl, and finally into 

 the fine dark marl that covers the bottom in all the deeper parts of the 

 lalve and which is the accumulation of plankton tests. The bottom 

 steadily grows softer as the proportion of dark marl increases. So soft 

 does it beeome that a small sounding lead sinks into it of its own weight 

 from G to 12 inches. In some places, especially tlie southwest side and 

 in the little lake the shalloAV part of the beach is formed of mucli which 

 shade>; off into marl without the presence of any sand or gravel. 



In geneiiil it may be said tliat the mussel zone extends from the 

 shore line to where the bottom changes to very soft marl. This region 

 will averag-e from 4 inches to 9 feet of Avater, although in some places 

 the mud comes to within a few feet of the water's edge, while in others 

 the sandy and gravelly bottom runs out into 22 feet of water. 



A. grandis is usually found just on the outer edge of the sand 

 and gravel bank, while A. edentnia appears most numerously a little 

 farther out. A few specimens of both species were taken closer in shore, 



"Contributions from the Zoological Laboratory oflndiana University, No. 62. 



