10 



MUSSEL FAUNA OF THE KANKAKEE BASIN. 



water. In addition the bottom of the lake, wherever it can be seen, is 

 entirely covered with plants, Chara and Potamogeton. In following 

 around the entire lake margin only a single spot was found free from 

 this vegetation. Finally the water itself is filled with a suspended 

 plankton which is entirely vegetative, made up mostly of minute 

 algse {Clathrocystis and Lynghya) . 



All the water plants are covered with a fuzzy growth of Meso- 

 carpus^ which also forms in floating masses, and with the ClatJv- 

 rocystis collected in large curdlike lumps. Such a lake does not 

 afford good conditions for either fish or mussels and both were very 

 scarce. A careful examination of the entire margin of the lake 

 yielded only 7 specimens of the " fat mucket " (Lampsilis luteolus) , 

 of which 5 were dead, 16 specimens of Anodonta grandis, 14 of 

 which were dead, and 1 dead Anodontoides femtssacianus suhcylin- 

 draceus. As it was of interest to know the food and parasites of 

 mussels living under such conditions, the four live specimens were 

 examined, with the following results: In A. grandis^ Atax was 

 abundant, with an occasional Cotylaspis. The distomid of Osborn ^ 

 was exceptionally abundant and made the nacre very rough, but 

 gave a dark discoloration instead of the usual salmon tint. The 

 stomachs yielded Clathrocystis and C cdosfherium in abundance with 

 some Pediastriim, In Z. luteolus both marginal cysts and the dis- 

 tomid of Kelly w^ere fairly abundant, with no other parasites. 

 Small pearls were found in the margin of one mantle and a small 

 dorsal baroque in the other specimen. The stomachs were filled with 

 Clathrocystis and Cosmarium well fused into a dark gritty mass. 



Station 5. Above the dam at Plymouth. — This dam was built 60 

 years ago, but has been washed out and rebuilt several times, the 

 last time without any fishway. It backs the water up the river 

 about 4 miles ; this dead water and the river for 2 miles above were 

 thoroughly examined, as well as the side lagoons, which are common 

 along the dead water. The center of the dead water was too deep 

 for wading and there were so many snags it was impossible to 

 dredge it. Elsewhere the mussels were widely scattered and not 

 many were found alive. In some places the banks were too soft and 

 miry, in others too hard and solid for mussels, and it was only the 

 infrequent spots between the two that yielded any returns. 



On examining the mussels for parasites the following were found : 

 In L. luteolus there were many cysts along the mantle margin and 

 the distomid of Kelly was fairly abundant. In many of the speci- 

 mens there were small pearls and in some of them dorsal baroques. 

 In A. grandis^ Atax was the most common parasite, with a few 



1 This name is applied to a distomid which was found by Prof. Osborn to be the cause 

 of salmon discoloration in Anodonta grandis ; investigations undertaken since the above 

 was written lead to the belief that the distomid in question, which produces a chocolate 

 instead of a salmon-colored stain, is of a different species. 



