146 DAYS OUT OF DOORS. 



depressions, both wider and deeper than these, and all 

 leading directly from the shore line of the pond toward 

 the brook. One that I followed from end to end was 

 deeply impressed with the tracks of a musk-rat that two 

 nights before had walked instead of swam to the middle 

 of the pond. I thought of mussels and looked for their 

 shells, for I always associate the mollusk with this animal, 

 but found no trace of them. This led me to wondering 

 what the musk-rats here did eat, and I found the bones of 

 frogs and a bird at the opening of another burrow on the 

 opposite side of the pond. The bird was a small heron, and 

 I will not presume that the musk-rat caught it ; that it 

 found the bird is far more likely. One feature of the 

 mammal's habits was evident a meat diet is preferred, if 

 not essential. In the tidal creeks a mixed one is the rule, 

 for many tender roots of water-plants are devoured. 



A word here about the mussels that in most places 

 constitute a large proportion of the musk-rat's food. The 

 shells that accumulate about the burrows and feeding- 

 grounds of the rat are not without scarification always, 

 as has been so persistently claimed. Directly below the 

 cliff, in Adams County, Ohio, whereon rests the Serpent 

 Mound, Brush Creek meanders over a rough and troubled 

 course, and is almost stayed at certain points by the huge 

 rock masses that have fallen into the channel. Here 

 musk-rats abound, and mussels are abundant. Upon 

 several projecting rocks I found scattered shells that 

 clearly exhibited tooth-marks, and several that were 

 broken about the edges, as teeth and toe-nails tugging at 

 them would be likely to break them. As a whole, my 

 gatherings would never lead one to suppose that valves 

 were ever parted without injury. Such, however, is the 

 case, and I have heard but a single explanation, although 

 I have asked many observers meaning by the latter- 

 trappers and others who had had abundant opportunities 



