Sounds and silence, 19, 20, 23, 26, 27, 133, 134. Springs, use of, 204. Spruce Tree Colony, harvest time with, 83-98; tunnels in, 113-115. Stream-flow, effect of beaver on, 72-74, 213-217. Strength, 9. Subways. _See_ Tunnels. Swimming, method of, 6. Tail, uses of, 5, 6, 11; form and covering, 8; signalling with, 24, 31, 96; fabulous accounts of the uses of, 53. Teeth, 7-9. Three Forks, Montana, 42, 79; canal system at, 107-111. Trails, 111, 112. Transportation of dam and food material, 86-90, 92, 93; canals used in, 106-115; trails and slides used in, 111, 112, 115; tunnels used in, 112-115. Trappers, 164, 189-191. Traps, 35, 189. Trees, cutting. _See_ Cutting trees. Trimming trees, 12, 96. Trout, 205, 206. Tunnels, 85, 112-115, 198, 203, 206. Water. _See_ Stream-flow. Water-ouzel, 199. Water-supply, 85, 86. Weather-wisdom, 44-47. Weight, 7. Wells, food, 103, 104. _See also_ Basins. Whistle, 26, 37. Wildcat, 35. Willow Creek, 176. Wind River, 102, 175, 182, 188. Winter, beaver life in, 197-209. Wolves, gray, 191, 197. Wood, dead, 143, 144. Work, accomplished by beaver, 3-5. Young, birth and care of, 27, 28; growth and play of, 28. The Riverside Press CAMBRIDGE . MASSACHUSETTS U . S . A