taxonomical advances stand among the most engaging of all lessons to the philosophic ornithologist. External appearances, it has taught among other things, are by no means a safe guide to the orderly classification of any series of objects. Some old works upon my library shelves, formerly considered "standard" and "classic," contain many chapters in those premises which are highly instructive on this point. One of them now open before me places, according to its author, such utterly diverse bird-groups as the trogans, the kingfishers, the swifts, the goatsuckers, and the humming birds, all among the Passeres. Linnæus and a number of his successors had no better appreciation of the truth, for the scientific light shed over such fields was to them still quite dim. He placed, with all confidence, the Caprimulgi in his order Passeres. Later, this created the usual intelligent, incredulous smile of the scientific taxonomer, and in the next epoch we find in their writings an "order" created to contain, among other types, the swallows, the swifts, and the goatsuckers! Then, too, think of Huxley, who as late as 1867, upon osteological grounds made a division Cypselomorplhæ, to which he restricted the swifts, the humming birds, and the goatsuckers. A decision of that kind coming from such an influential quarter has carried with it the weight of conviction to the minds of our most recent ornithological writers and systematists. And we find Elliott Coues, in his last revised edition (1890) of his Key to North American Birds, still adhering to the old order Picariæ, in the first group of which, the Cypseliformes, he places the swifts (Cypselidæ), the goatsuckers (Caprimulgidæ), and the humming birds (Trochilidæ). But a far more unnatural grouping is seen in the Manual of North American Birds, by Mr. Robert Ridgway, where an order Macrochires is retained to contain the goatsuckers, the swifts, and the humming birds, and in this he is followed by the check list of the American Ornithologists' Union. What special kinship the systematist sees between a humming bird and a whip-poor-will, the morphologist in these days certainly fails to appreciate. Anatomically the writer has examined in great detail several species of different genera of both humming birds and goatsuckers, as he also has many swifts and swallows, and is of the opinion that the Caprimulgi are most nearly related to the owls, while the swifts are but profoundly modified swallows. To thoroughly appreciate such affinities it is necessary that we should have before us the so-called "outliers" of the various groups just named.
Representatives of the suborder of birds, United States species of which we are here considering, are found in many parts of the world, though they appear to be entirely absent from the avifaunæ of Polynesia and New Zealand. In South America, in Asia, in Africa, and in Australia we meet with goatsuckers of the most