18 



MUSSEL FAUNA OF THE KANKAKEE BASIN. 



cysts. Some specimens contained 30 or more of the adult para- 

 sites, besides innumerable young swarming over the gills or the 

 mantle. 



The bed of mussels along the center of the north shore gave a 

 remarkably fine opportunity to study the activities of the mussels 

 in the natural beds, as the perfectly clear, calm water enabled one 

 plainly to see them carrying on their life processes. The species 

 examined was the Anodonta grandis of the lake, a plump, inflated 

 form which probably represents the subspecies footiana. 



The inhalent aperture was very large^ black exteriorly and for 

 some distance in. It was possible to look in far enough to see the 

 gills. Long papillae in approximately a single row project directly 

 across and nearly to the center of the siphonal opening; most are 

 single, but a few may be forked. The incoming current of the mussel 

 is not nearly as strong as the outgoing, since the latter has a much 

 smaller cross-section for the same amount of water. Minute red 

 water mites ventured to the very orifice of the inhalent aperture but 

 were not swept in, while small objects coming near the exhalent 

 opening would be driven away with some force. 



The exhalent opening was black for some distance in, then faded 

 out to white. It was possible to see the posterior opening of the 

 alimentar}^ canal and the water-tubes running down into the gills 

 of the living mussel. These mussels were quite apathetic; they did 

 not close up at near approach, which must have caused both shock 

 of waves and shadow. One, taken from the bed, closed only for a 

 moment, then opened and began feeding while held in the hand. 

 Eiver mussels in general are more sensitive, and sometimes close 

 when simply a shadow passes. 



Station 12. Potato Creeh^ Kankakee River. — Having finished the 

 workable portion of Yellow River, our attention was next directed 

 to the headwaters of the main Kankakee. 



At its source this river forks like the Yellow River, the west fork 

 rising in the Fish Lakes^ the east fork in the swamp southwest of 

 South Bend. We found conditions here similar to those at the head- 

 waters of Yellow River, but with this difference: While the east 

 fork and the main river have been dredged recently down to the 

 entrance of the Yellow River and about 10 miles beyond, many of 

 the tributary creeks have been left in their original conditions; and 

 since the west fork has been dredged only here and there, the Fish 

 Lakes^ at its source, remain practically unchanged. We were thus 

 able to combine in our examination natural with artificial conditions, 

 and we found an even stronger contrast between the two. 



This entire section was worked by short drives from Walkerton, 

 in the extreme southwest corner of St. Joseph County, since it was 



