MUSSEL FAUNA OF THE KANKAKEE 'BASIN. 11 



Cotylaspis. The distomid of Osborn was abundant, producing a 

 dark discoloration and rough nacre like that found at the Lake of 

 the Woods. 



Station 6. Below the davv at Plymouth. — This station offered a 

 pleasing contrast to the preceding. The water was shallow, the 

 maximum depth being 2 feet, the bottom was firm sand and gravel, 

 and the current was about 3 or 4 miles an hour. From the dam to 

 the mill race we found good collecting ; below there the river became 

 deeper and there were not as many mussels. 



Of the specimens obtained one small L. ventricosus had a very 

 thin shell with pink nacre ; ^4 . imhedllis was quite common and five 

 were obtained that were gravid; one L. parvus was also found 

 gravid; a few L. iris and large A. calceola were found along the 

 shore. 



In addition to the mussels collected by the authors here, Mr. 

 Aaron Greenwaldt, who had collected shells from the river for the 

 State Geological Survey, presented the Bureau of Fisheries a beauti- 

 ful collection of 125 shells very perfectly cleaned and kept with the 

 two valves tied together. For this valuable present the authors 

 here return sincere thanks. The collection included the following 

 species, the number of specimens being given after each : Q. coccinea, 

 16; Q. ruhiginosa^ 6; Q. pustulosa, 3; Q. undulata (from above the 

 dam), 6; S. costata, 12; S. compressa, 7; A. imhedllis, 1; S. eden- 

 fulus, 2; x4. grandis, 10; L. iris, 6; L. luteolus, 20; L. ventricosus, 

 21 ; U. gihhosus, 15. 



Of the small fishes obtained at this station the straw-colored min- 

 now (Notropis hlemiius), chub {Semotilus atromaculatus) , and 

 Johnny darter {Boleosoima nigrum) were particularly abundant and 

 many of each species were put back into the river. A consider- 

 able number of the young straw bass {Micropterus salmoides) and 

 grass pike {Esox vermieulatus) were also caught, but only one or 

 two samples were kept. We were told there was a severe attack of 

 the " pearl fever " here during the previous year and that the boys 

 brought out and examined mussels by the barrel without material 

 results. If so, they must have disposed of the shells, since none were 

 found except a single pile, containing about a ton and a half, a short 

 distance below the dam. 



Station B. Pretty Lake. — Pretty Lake, situated 3 miles southwest 

 of Plymouth, is a typical glacial kettle hole, nearl}^ circular in out- 

 line and about half a mile in diameter. The water is remarkably 

 clear and has a fine greenish tint, like that of Lake Maxinkuckee. 



It is fed by springs, the entire northeastern shore being covered 

 with them, and at present has no outlet. There is a single inlet at 

 the northwest corner which is a dry run most of the time, but the 

 presence of a large gravel delta testifies that at times it discharges 



