24 



NORTH AMERICAN FAUNA. 



[NO. 16. 



Tlie banks of the more periusmeiit streamlets are so M'ell supplied 

 with moisture that the heather and other i)lants, often mixed with 

 alpine mosses,^ form a sod which, growing thicker eacli year, gradually 

 comes to overhang and tinally bridge the swiftly running water. Even 

 away from these sod bridges, which for long distances completely hide 

 the winter, the space between the constantly protruding banks is so 

 narrow that only the middle part of the stream can be seen. 



The icy rivulets abound in cascades, miniature waterfalls, and crys- 

 tal pools, bordered by overhanging banks of moss, heather, and dwarf 

 alpine laurel, and adorned by the waving heads of the scarlet i)ainted 



FlU. 11.— Aliiiiatiiie riiscailc on iippi'i- S(iiiaw Ci-it-k, f iciiiirntcd liy watiT sliixw.s and ouzels. 



cups and cream-colored parnassias. They are ideal homes for the water 

 on/.iil {Cincl us me.ricdnus), the large water shrew {Xeosorc.r n((ri()((t<>r), 

 and the mountain vole {Microtiis itiortht.r). The latter animal is i)ar- 

 ticularly abundant, and its dark burrows, almost hidden among the 

 plants, may be found opening out on the vertical overhanging baidcs 

 only a few inches above the water, so that whenever the occupants 

 come out they may plunge in the icy stream before proceeding on their 

 journey. Miid<s occur lower down along the streams, and still lower, 

 otters. 



' The prevail in;; m 

 num. 



oil tlio i),inl<s of till- ;il[)iiic >ti(:iiii.s i.s .1 iilminii niiini <indrogy- 



