34 



MUSSEL FAUNA OF THE KANKAKEE BASIN. 



Station 31^^ Mazon Creek^ Gardner^ III. — This is another tributary 

 of the Kankakee from the north and in its general features closely 

 resembles Forked Creek. It consists mainly of rather shallow pools 

 connected by slender threads of water, with numerous sand and gravel 

 bars. The bottom is practically all pebbles and sand, with almost no 

 mud. Water willows are thickly distributed, with large patches of 

 spatterdock, but there were not many algse. 



The mussels were found mostly along the edges of the sand bars 

 and were usually small in size. Many of them were actively 

 crawling about and lay at the ends of long furrows. Pearlers had 

 been at work here also, and many recently killed shells were seen 

 along the banks, mostly Q. undulata.^ with some L. luteolus. The 

 muskrats were evidently abundant and had left many dead shells 

 scattered along the w^ater's edge, chiefly the small L. ellipsiformis 

 and young specimens of Q. undulata^ S. complanata, and S. edentulus. 



The L. ellipsiformis was particularly abundant and an excellent lot 

 was obtained. The young S. edentulus and S. complanata were all 

 bright-rayed. One edentulus and most of the ellipsiformis were 

 gravid, and in the former was a single large Atax ingens^ the only 

 parasite found. The dead shells of luteolus ^ however, looked as if 

 they had been well parasitized and had contained many pearls. One 

 pearl about the size of a small buckshot was obtained from a living 

 specimen, which contained many marginal cysts. This pearl was 

 perfectly spherical, and though fresh, was of rather poor luster. 



Station 35, Mouth of the Kankakee River. — The Des Plaines River, 

 which joins the Kankakee to form the Illinois River, is simply an 

 immense sewer bringing down the Chicago drainage. Both rivers, 

 but especially the Des Plaines, are full of the characteristic algae 

 and other vegetation which grow in such waters, and the combi- 

 nation of a copious vegetation with the sewage has effectually killed 

 off all the mussels in the vicinity. Not a single living specimen 

 could be found in either river, but there were hundreds of dead 

 shells along the banks, most of them old and well bleached, but still 

 capable of identification. The species listed from this station are 

 all such dead shells. 



Since this finishes the examination of the Kankakee Basin, it 

 will be well to sum up the general results of the work in the form 

 of brief statements : 



SUMMARY OF MUSSEL DISTRIBUTION. | 



1. The Kankakee River and its two principal tributaries, the 

 Yellow and Iroquois Rivers, present a very rich and varied mussel 

 fauna throughout their entire lengths, except in those portions which 

 have been artificially dredged. 



