30 MUSSEL FAIJKA OF THE KANKAKEE BASlN. 



River, and hence did not bring quite as much per ton. They showed 

 us a good collection of pearls and baroques obtained from their mus- 

 sels, and just as we landed they picked a large spherical pearl the 

 size of a pea out of the mantle of an L. ligamentinus. We looked 

 over their pile of shells and took samples of the different species ; the 

 great bulk of the pile was ligamentinus and ventricosus. 



We secured the following species which had not been found in 

 the river above: L. ellipsiformis^ common; Q. tuberculata^ several; 

 Q. metanevra^ rather common; A. truncata^ frequent; S. edentulus^ 

 two; S. costata., common and large; O. ellipsis^ two. Some of the 

 L. rectus had white nacre, but most were pink; the U. gihhosus 

 showed purple, pink, and white nacre^ with considerable difference 

 in shape and size of shells. 



Station 25. Waldron, III. — The river was shallow and rocky and 

 very difficult to navigate below Momence, but the water was fairly 

 clear, so the shells could be seen on the bottom. There was consid- 

 erable Potamogeton lonchites and water willow along the water's 

 edge. Beds of mussels could be seen in various places, especially 

 near the riffles ; but as the mussel fishermen at Momence had worked 

 this part of the river thoroughly, no stop was made until we were 

 close to Waldron. Here was found a pile of freshly cleaned shells, 

 about one-quarter of a ton, which had been left by pearlers. Sam- 

 ples of the different species were selected and kept; the pile was 

 nearly all L. ligamentinus., with some L. ventricosus and U. gih- 

 hosus; the other species listed occurred in small numbers. One of the 

 L. rectus had white nacre, the first white-nacred one seen; the rest 

 were pink. Both the ligamentinus and the ventricosus had been 

 gravid in considerable numbers when captured. 



At Waldron an 8-foot dam prevents all intercourse with the river 

 farther down. 



Station 26. Watsel>a, Iroquois River. — This river is the chief tribu- 

 tary of the Kankakee in Illinois as was the Yellow River in Indiana. 

 Like the main river, the character of this tributary changes radi- 

 cally at Watseka. Nearly half the river basin, 800 square miles, lies 

 in Indiana, and is of the same type as the Kankakee Basin in that 

 State, marshy and sandy. 



Just before reaching Watseka, 111., it crosses the so-called Iroquois 

 moraine and afterwards traverses an old lake bed. There is much 

 more fall in the river, but it is never as rapid as the Kankakee. The 

 great amount of dry prairie land it drains makes it a " flashy " 

 river, subject to rapid rise and fall, and hence the upper portions 

 of it are not very rich in mussels. Furthermore, in the vicinity of 

 Watseka the banks of the main river and of Sugar Creek, a large 

 tributary from the south, are so steep and slimy with clay that it 

 was practically impossible to do any wading. The collection of 



