.--wing to the tremendous degree of morpho- logical uniformity within the class Aves, presumably because of the restrictive physical demands of flight, the relationships of the higher taxa of birds are perhaps the most poorly understood of all the vertebrate groups. Particularly enigmatic have been the relationships of the major groups of the massive order Passeriformes. The order Passeriformes has been subdivided classically on the basis of syrinx mor- phology into two major groups, the "oscine" passerines (suborder Passeres), which possess a complex syrinx with more than three pairs of intrinsic syringeal muscles, and a heterogeneous group known as the "subosdnes," which have been thought to be the more primitive because they have an anatomically simpler syrinx than that found within the osdnes (Ames 1970, Peabody Mus. Nat. Hist. Bull. 37). The "suboscines" comprise several groups, presently given subordinal rank by most authors Figure I. Alizarin-stained stapes of A, Spreo superbus (oscine: Starling); B, Xiphocolaptes promeropirhynchus (New World suboscine: Woodhewer); and C, Pitta angolensis (Old World suboscine: Pitta). All approximately X40. Stapes may be prepared after extraction from the ear either by coating them with a conductive substance such as gold for scanning electron microscopy, or by staining with Alizarin Red S and placing them in vials containing glycerine. Alizarin-stained specimens are more easily studied with conventional light microscopy, and are easily photographed under any normal scope; all specimens in Figure 1 were prepared in this manner. (see Wetmore 1960, Smithsonian Misc. Coil. 139 (11); Storer 1971, Classification of birds. Pp. 1-18 in Avian biology, vol. 1 (D. S. Farner and J. R. King, Eds.), Nexv York, Academic Press), xvhich occur in both the Nexv and Old World regions, pri- marily in tropical and subtropical zones. The question of the relationship of Nexv to Old World groups has been a subject of great controversy for more than a century, and at present there is little agreement because the possession of a simple syrinx in these zoogeographically isolated groups may represent the retention of a primitive character state rather than an indication of evolutionary affinity. The form of the small afan bony stapes vas examined in several groups at the turn of the century (Krause 1901, Die Columella der VSgel, Berlin, R. Friedlinder and Sohn), but no comprehensive study has ever been achieved. I have examined the morphology of the bony stapes in more than 1,1300 species. I have discovered that (1) the vast majority of birds (most of the nonpasserine orders, and the entire "osclne" passerine assemblage) possess a bony stapes resembling the primitive reptilian condition, with a flat footplate, and a straight bony shaft (Figure 1A). The xvide- spread occurrence of this type of stapes probably represents the retention of the prim- itive condition. The major groups of the "suboscines" (Table 1) share a derived morphology of the stapes, characterized by a large bulbous footplate area perforated usually by one large (often one large and one small) fenestra (Figure lB, 1C, and Figure 2). In this condition the shaft is similar to the primitive condition, but is necessarily shortened by the expansion of the footplate. The similarity of the stapes in the Old World Eurylaimidae and Pittidae, and the Nexv World Furnariidae, Dendrocolaptidae, Formicariidae, Conopophagidae, Rhinocryptidae, Cotingidae, Pipridae, Tyrannidae, and Phytotomidae is strong evidence for a common origin of these Nexv and Old World groups. A study of the morphology of the stapes in all birds is currently being prepared for publication in monograph form. Figure 2. SEM photo of the stapes of the Ovenbird, Furnarius ruJus, a New World suboscine bird, approximately X 50. TABLE 1 SPECIMENS OF SUBOSCINE BIRDS EXAMINED  Number examined 2 Number examined 2 Genera Species Genera Species Eurylaimidae 2 2 Cotingidae 21 30 Furnariidae 30 53 Pipridae 9 18 Dendrocolaptidae 10 23 Tyrannidae 70 124 Formicariidae 27 39 Phytotomidae 2 2 Conopophagidae 2 2 Pittidae 1 9 Rhinocryptidae 2 2  Material from the rare Oxyruncidae, Acanthisittidae, Philepittidae, Menuridae, and Atrichornithidae is still incomplete. 2 All but four of the families of the oscine passefine birds were examined. This work was supported by a grant from the University of North Carolina Re- search Council. R. W. Storer (University of Michigan), and R. L. Zusi (National Museum of Natural History) permitted me to use collections under their care. I wish to thank W. H. Zucker for instruction and help with the SEM work (Figure 2) that was done in the laboratory of R. Mason, Jr. (Pathology, University of North Carolina), and H. C. Mueller and R. H. Wiley for comments on the manuscript.- ALAN FEDUCCIA, Department of Zoology, University of North Carolina, Chapel Hill, North Carolina 27514. Accepted 21 Nov. 73. (This paper was subsidized by the University of North Carolina Research Council.)