32 MUSSEL FAUNA OF THE KANKAKEE BASIN. 



even more apparent here; the river was shallow and full of riffles 

 and the bottom was almost continuous rocks, with little sand or mud 

 between them. But the shores still showed the obnoxious black 

 clay mud. 



Fortunately, the muskrats had been busily at work eating the 

 smaller mussels with some of the large ones, and had collected large 

 •piles in many places. The mud on shore was nearly a solid network 

 of muskrat tracks, with here and there the long groove where they 

 had dragged a shell too large to lift and carry. They evidently had 

 no trouble in finding plenty of mussels, although we could not locate 

 the live ones among the rocks. The 15 species listed were all obtained 

 from the muskrat piles, and, as will be seen, include Q. Tnetanevra^ 

 which evidently prefers localitias with a very rocky bottom. 



Station 29. Month of the Iroquois River. — Where the Iroquois 

 joins the Kankakee, there are two or three small islands, raised 

 but little above the level of the water, but giving support to a mass 

 of dense underbrush. 



Here again the muskrats had nearly covered the mud around the 

 roots of the bushes with nicely cleaned mussel shells of many 

 species — probably all that can be found in the vicinity. Two Q. 

 laekryTTiosa were found alive at the water's edge; all the others 

 collected were the shells from the muskrat piles. 



Station 30. Kankakee^ III. — Several pearlers had been at work on 

 this portion of the river and about 1 mile above the city of Kankakee 

 were two large piles of shells close to the water's edge on the south 

 bank. The first pearler, and evidently the more experienced one, had 

 collected only L. luteolus.^ but his pile of shells did not show proof 

 of having yielded many pearls. The other party had collected all 

 species indiscriminately, and 14 different kinds were found in the 

 pile. None of these shells gave evidence of ha\dng been much para- 

 sitized and probably did not yield very large returns. They gave 

 us a fine collection from the locality, however, without the trouble 

 of wading and hunting for them. 



The selection of luteolus as a pearl producer is worthy of notice, 

 since it coincides exactly with our own experience in the whole 

 Kankakee Basin. The pearl problem is quite possibly different in 

 each river. In some rivers Q. undulata or plicata are regarded as 

 the pearl-bearing shells; in others, L. ligamentinus, and so on. In 

 the Kankakee Z. luteolns was the most prolific, and indeed the only 

 species that one could count on to yield them, but the pearls were 

 all, though perfectly spherical and of good luster, of very small 

 size, called by the pearlers " mustard-seed pearls." 



Station 31. Custer Park., III. — Just below the city of Kankakee 

 there are five large dams across the river within a few miles, while at 

 Altorf and Wilmington thei-e are rapids with a sudden descent of 20 



