_urubú_ or vulture, that bird being considered too large, heavy, and ignorant of architecture to assist personally in the work. In the southern part of South America, where scattered thorn trees grow on a dry soil, these big nests are most abundant. "There are plains," Mr. Barrows writes, "within two miles of the centre of this town (Concepcion, Argentine Republic), where I have stood and counted, from one point within a radius of twenty rods, over two hundred of these curious nests, varying in size from that of a small pumpkin to more than the volume of a barrel. Often a single tree will contain half a dozen nests or more; and, not unfrequently, the nests of several different species are seen crowding each other out of shape on the same bush or tree." It would be a mistake to think that the widely different nesting habits I have mentioned are found in different genera. I have just spoken of the big stick nests, with or without passage-ways, of the Synallaxes, yet the nest of one member of this group is simply a small straight tube of woven grass, the aperture only large enough to admit the finger, and open at both ends, so that the bird can pass in and out without turning round. Another species scoops a circular hollow in the soil, and builds over it a dome of fine woven grass. It should be mentioned that the nesting habits of only about fifteen out of the sixty-five species comprised in this genus are known to us. In the genus Furnarius the oven-shaped clay structure is known to be made by three species; a fourth builds a nest of sticks in a tree; a fifth burrows in the side of a bank, like a kingfisher.