When the children had finished applauding Olive's poetry--or was it really the Thrasher's own performance?--the Doctor went on: "We have seen that the West has one sort of a Thrasher in the sage-brush, and the East another, in our own gardens. I also told you that these birds were a kind of overgrown Wren; and before we call upon Mrs. Jenny Wren, I want to tell you about a bigger relative of hers that Olive and I knew when we were in the Rocky Mountains. He is called the Rock Wren--" "Oh! I know--because he lives in the Rocky Mountains," said Dodo, clapping her hands at this discovery. "Yes, that is partly the reason," resumed the Doctor, after this interruption, "but those mountains are very many, and varied in appearance, like most others: covered in most places with pine trees, but including in their recesses grassy meadows and silvery lakes. Some parts of those mountains are the home of the Rock Wren, but the little fellow is quite as well satisfied anywhere else in the western parts of the United States, if he can find heaps of stones to play hide-and-seek in with his mate, or great smooth boulders to skip up to the top of and sing. So you see the mountains and the Wrens are both named for the rocks. "Do these Wrens look like our kind and act that way?" asked Nat. "Ours always make me think of mice." "All kinds of Wrens are much alike," answered the Doctor. "They are small brownish birds with cocked up tails, not at all shy about showing themselves off, when they choose, but they must have some hiding-place to duck into the moment anything frightens them, and some odd, out-of-the-way nook or cranny for their big rubbishy nests. Some prefer to hide in marshes among the thickest reeds, some live in dry brush heaps, and some, like the Rock Wren, choose piles of stones. Their wings are not very strong, and they seldom venture far from their favorite retreats, except when they are migrating. "When your cousin Olive and I were in Colorado we climbed a mountain one day above the timber-line"-- "Do _all_ the trees out there grow in straight lines?" asked Dodo anxiously. [Illustration: Rock Wren.]