MUSSEL FAUNA OF THE KANKAKEE BASIN. 



13 



A, grandis^ and L. ligamenthms. None occurred in the shifting sand, 

 but where the sand was firmly packed and among the rocks they were 

 placed almost as thick as they could lie. Z. ventricosus and U, 

 gihhosus were most abundant and occurred in about equal numbers. 

 The ventricosus were all upright, the tips pointed upstream, and 

 the entire mussel buried with the exception of the large brown 

 siphons. The gihhosus were more active, moving about in every 

 direction, and often found lying flat on one side. S. costata was also 

 very common and when buried, with only the crinkled edge showing, 

 was easily mistaken for undulata. A single L. rectus was found 

 lying upon its back and spawning. Nearly all the costata also were 

 gravid, and most of them contained one or more dorsal baroques, 

 yellowish in color. The Q. coccinea nearly all had pink nacre. 



The shells obtained at this station were of large size, particularly 

 the pocketbooks (Z. ventricosus)^ and of excellent luster. And it 

 is certain that a qualitative examination would show them to be as 

 valuable as any obtained during the entire summer. 



Station 8. Yellow River at Burr Oak. — This is the station where 

 the boat and outfit were launched for the trip down the river. The 

 conditions were identical with those at Hibbard, except that the 

 current was a little swifter — 4 miles an hour. Potamageton natans, 

 Cladophora^ and Tetraspora were found in patches on the mussel 

 beds. As before, the mussels were found mostly in the gravel and 

 hard sand and were completely buried, except the siphons. Many 

 of the ventricosus and some of the gihhosus were spawning and it 

 was noticeable that the small fishes, especially Notropis hlennius^ 

 Boleosoma^ and Semotilus^ which were the ones most abundant, kept 

 playing about near the spawning mussels. 



Station 9. County Line Bridge^ ^ miles west of Burr Oak. — This 

 was a broad, pond-like stretch of river, with a sluggish current, 

 plenty of spatterdock and white water lilies, a bottom of hard mud 

 and fine gravel, and banks of seepy blue clay. 



Not many mussels v/ere collected here — just enough to show that 

 they were still scattered plentifully along the river bottom. 



Station 10. Zinc Bridge at Oher. — The water was shallower than 

 at the preceding station, with a maximum depth of only 2 feet, and 

 a current of 5 miles an hour ; the other conditions were the same. 



The mussels were thickly scattered everywhere, with especially 

 dense beds along the shore. The small fish were again noticed play- 

 ing about in the immediate vicinity of the spawning mussels. 



L. ventricosus has a habit of moving its bright yellow siphon 

 fringes, which are much enlarged during spawning, back and forth 

 in the water. This undulatory motion seems to attract the small 

 darters and minnows, particularly Notropis hlenniusy which could 



