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Show 1885.] TROCHILIDiE, CAPRIMULGID.E, AND CYPSELID.E. 907 the prominent, triangular, costal processes, with their borders them each of the latter supporting five articular facets. From the last ot these the sternal body becomes progressively wider to terminate in acute posteroexternal angles formed by the intersection of tne unnotched, slightly convex, xiphoidal border. So thin are the walls of the body of this sternum that we frequently find large vacuities existing in it that tend to be symmetrical in character for either side of the carina. This attenuity of the sternal body does not apply, however, to its margins the two lateral, as well as the hinder one, being characterized by a thickened deposit of bone. Upon a lateral view we are enabled to see that the sternum of this bwift develops quite a prominent manubrium, which stands between the coracoidal facets. These latter are of an oblong form, with their long axes parallel to the plane of the keel. The keel is thickened in front, and concave forwards. Its angle is rounded off, and the line of its lower margin nearly straight; it may, too, show deficiencies in its substance similar to those in the body. This keel to the sternum of the Swift is not so deep in comparison with the remainder of the bone as we often find it amono- the Passeres, and in this particular it is not to be mentioned with the extraordinary carinal development in Trochilus (Plate L X . fig 6) A glance at Plate L X . fig. 2, is sufficient to convince us that Panyptila has a shoulder-girdle differing in many important respects from the Humming-birds, as well as the typified arch of the Passeres. Its furcula is broadly U-shaped, with scarcely any hypocleidium developed below. The apices of the heads reach back to the scapulae, and they also possess the outer lateral abutments (fig. 2 z) for the heads of the coracoids, much as we found them in Nuttall's Whippoorwill. As for coracoid and scapula, the former has a prominent head directed forwards and upwards, a shaft shorter than in the Swallows • but otherwise both this bone and the latter differ in no leadin-details from the same elements as found in these birds. And at the same time it is hardly necessary to add, after what has gone before, that it, as a whole, differs fundamentally and in essential details from' the girdle in Trochilus. Swallows, as we know, have both sternum and pectoral arch agreeing with the Passerine type. This family also has the os humero-scapulare developed, a fact which intimates that the affinity between these two groups is still the closer. Of the Pectoral and Pelvic Limbs in the Humming-birds, Nightjars, and Swifts (Plate LXI. figs. 1, 3, and 4).-So far as 1 have examined them, the Caprimulgiue birds have their pectoral limbs constituted as in the ordinary representatives of the class. The humerus, in proportionate length with the bones of the antibrachium (fig. 1), has quite a straight subcylindrical shaft, a rounded and rather short radial crest, a pneumatic fossa and foramen, arched over in the usual manner by the ulnar crest, and finally a distal extremity |