14 MUSSEL FAUNA OF MAUMEE EIVER. 



Hagen, and the river bottom appeared to be ahiiost overpopulated 

 with them. The young were often seen crowding up close to the 

 shore. As noticed above, many w^ere thickly covered wdth a growth 

 of protozoa, and some of the young Avere covered with a green algal 

 growth. In the mussel bed the crawfishes were seen sunning them- 

 selves on the rocks which projected out of the water, lifting them- 

 selves high upon the pincers in a most peculiar fashion. Upon 

 wading out to a large projecting rock situated in the river about in 

 the middle of the mussel bed they were found to be clustered thickly 

 on the sloping surface of the rock just at the water line, their heads 

 projecting out of the water. Many were found living in dead mussel 

 shells just below the bed; indeed, it was hardly possible to pick an 

 old shell or tin can out of the water without obtaining a crawfish. 

 Some of those thus captured were of very large size. The crawfishes 

 were frequently observed devouring the flesh of dead mussels, but it 

 is doubtful whether they were able to kill any, especially the larger 

 ones. They may possibly be an intermediate host of some of the 

 mussel parasites. The crawfishes were caught in considerable num- 

 bers, either by dip nets or minnow seines, for fish bait and were used 

 in the St. Joseph River. On July 2 a man was observed seining 

 craw^fishes just below the mussel bed at the riffles. The seine was 

 drawn over the bottom, which was covered with rounded pebbles 

 about the size of hen's eggs or larger, and the ends of the brails 

 poked about among the rocks. The crawfishes, of which it seemed 

 there was one under nearly every stone, backed up into the net and 

 ■^ere caught in great numbers. The fisherman wanted only -the soft- 

 shells and "peelers" (crawfishes about to molt) and threw the rest 

 back. A great number w^ere molting at the time. The " peelers " 

 can be easily distinguished from other crawfishes by pressing the 

 sides of the carapace, which arches up free from the body. They 

 also have a somewhat different color. The molted carapaces of 

 craw'fishes and gastroliths associated with them were quite common 

 along the shore of the river. 



No crustaceans except crawfishes were noted in the river itself, 

 though small Entomostraca were abundant at the edge of the river, 

 in overflow pools. 



Aquatic insects and larvae did not appear to be particularly abund- 

 ant so far as species were concerned; a few forms, however, were 

 quite common. The red "blood worm" (a Chironomus larva) was 

 present in large numbers, and along shore, just under the water 

 surface and attached to submerged objects by a short slender pedicel, 

 was a great number of small gelatinous pear-shaped objects full of 

 minute dots, probably o^gg bunches of Chironomus. Midges WH^.re 

 abundant, emerging in great numbers; on the morning of June 21 



