a reversed position,—that is, tail up and head down. This has an obvious advantage, in that the builder can see what is going on beneath him, and shows, too, how near the ground the nest will come when finished; but it sometimes happens that he gets so absorbed in his work that a person can approach quite near, but I never knew him to become entangled in the loose ends that hang about him. The oriole at times offers us a wonderful example of ingenuity. It occasionally happens that too slight a twig is selected, and when the nest is finished, or, later, when the young are nearly grown, the structure hangs down too low for safety or sways too violently when the parent birds alight on it. This is a difficulty the bird has to contend with, and he has been known to remedy it by attaching a cord to the sustaining twigs and tying them to a higher limb of the tree, thus securing the necessary stability. A more familiar evidence of the intelligence of birds is when the vireos are disturbed by the presence of a cow-bird’s egg in their nest. To get rid of it, they often build a new floor to the nest, and so leave the offending egg to spoil. But there is displayed here an error of judgment that I am surprised to find. The birds that take this trouble certainly could throw the egg out, and, I should think, preserve their own eggs, which invariably are left to decay when a new structure is reared above the old. I believe even three-storied vireos’ nests have been found. There is one common swallow that is found well-nigh everywhere, which burrows into the sand; and when we think of it, it seems strange that so aerial a bird should build so gloomy an abode for the nesting season. This bank swallow, as it is called, selects a suitable bluff, facing water, and, with closed beak, turns round and round with its head to the ground, thus boring a hole big enough to crawl into. It turns into a gimlet for the time, and uses its beak as the point of the tool. This is odd work for a bird that almost lives in the air; and then think, too, of sitting in a dark cave, sometimes six feet long, until the eggs are hatched. On the other hand, the barn swallow makes a nest where there is plenty of light and air, and is a mason rather than a carpenter or miner. The mud he uses is not mere earth and water, but is made more adherent by a trace of secretion from the bird’s mouth; at least, my experiments lead me to think so. To build such a nest would be slow work did not the two birds work together and carry their little loads of mortar with great rapidity. They waste no time, and use only good materials, for I have noticed them, when building, go to a quite distant spot for the mud when a pool was directly outside of the barn in which they were building. To all appearance the nest is of sun-dried mud, but the material has certainly undergone a kind of puddling first that makes it more adherent, bit to bit, and the whole to the rafter or side of the building.