22 EVERMANN AND CLARK 



the Muskrat, however, is the freshwater mussels or Unionidae. 

 At various places along the shore, wherever an object projects out 

 into the water, such as a log or pier, or fallen tree-top, there will be 

 found in autumn or early winter a pile of mussel shells where 

 muskrats have been feeding. These piles are frequently of con- 

 siderable size, containing sometimes a bushel or more of shells. 

 September 24, 1907, one of these piles on Long Point was examined. 

 It was off shore several feet and in water 18 inches deep. About 

 one-half of the shells were examined critically and counted. There 

 were 532 shells, representing 4 species as follows: Lampsilis luteolus, 

 358; Unio gibbosus, 167; L. iris 6; and L. multiradiatns, i. 



During the fall these operations are probably confined to mussels 

 which they find in shallow water near shore. In winter, however, 

 when ice-cracks form and extend well across the lake, the Muskrats 

 go far out on the ice, dive through the cracks and bring up mussels 

 which they eat sitting on the ice. At such times they get mussels 

 at considerable distances from shore. In the first days of January, 

 1905, a broad crack formed in the ice from Long Point to the 

 Norris boat-house. On January 4, a Muskrat was seen at the edge 

 of this crack about 1000 feet from shore eating mussels. It would 

 dive through the crack and after a little while reappear with a 

 mussel. Sometimes it dived 5 or 6 times before securing one. 

 It would then sit up on its haunches, holding the mussel in its paws 

 and, by much clawing and chewing, finally succeed in opening the 

 shell and removing the meat, which it usually licked out quite clean. 

 In some cases the muskrat failed to get the shell open. Usually 

 the shells are but little or not at all broken; even the hinge still 

 holds and the shells are scarcely injured. It is our observation that 

 the Muskrat, by inserting its claws or teeth between the valves 

 succeeds in cutting or tearing loose the adductor muscles so as to 

 permit the valves to spring open. Another Muskrat was observed 

 further out on the same crack, a long distance from shore, and the 

 ice along the crack between the two was pretty thickly strewn with 

 shells. The Muskrats apparently do not care so much for mussel 

 gills filled with eggs or glochidia, as these were usually rejected. 

 The stomach of a Muskrat examined at Washington, D. C., late 

 in the spring was found well-filled with mussel remains. Muskrats 

 also feed to a considerable extent on fish, crawfish and frogs. We 



