1885.] TROCIIILFD/E, CAPRI MULGI D.E, AND CYl'SKLID.E. 907 



the prominent, triangular, costal processes, with their borticrs behind 

 them, each of the latter su|)porting five articular facets. From tlie 

 last of these the sternal hotly becomes progressively wider to termi- 

 nate in acute postero external angles formed by the intersection of 

 the unnotched, sliglitly 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 atteuuity of the sternal body does not apply, however, to its 

 margins, the two lateral, as well as the hinder one, being charac- 

 terized by a thickened deposit of bone. 



TJpon a lateral view we are enabled to see that the sternum of this 

 Swift develops quite a prominent manubrium, which stands between 

 the coracoidal facets. These latter are of an oblong form, w ith 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 among the 

 Passeres, and in this particular it is not to be mentioned with the 

 extraordinary carinal development in Trochilus (Plate LX. fig. 6). 



A glance at Plate LX. fig. 2, is sufficient to convince us that 

 Panyptila has a shoulder-yinlle 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 (tig. 2 z) 

 for the heads of the coracoids, much as we found tliem 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- scapular e 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, Night- 

 jars, and Swifts (Plate LXI. figs. 1, 3, and 4). — So far as I have 

 examined them, the Caprimulgine 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 



