91 



he hummingbird, while the swallow shows an entirely different pattern, 

 closely resembling that of the finches. 



' Again, the breast- bone, or sternum, is a bone of great importance in 

 all flying birds, as it gives origin to the powerful muscles which move 

 the wings. Here, too, the swift and the hummingbird show a similar 

 model, the swallow and the finch another. 



' The swallow is not a singing bird, yet upon dissection, the syrnix, 

 or origin of voice, at the lower end of the windpipe, is found in one of 

 its most highly developed forms, as in the true songsters. Ages ot dis- 

 use do not seem in this instance to have caused a degeneration of the 

 organ. Upon the swift and the hummingbird, on the other hand, no 

 reproach can be cast for neglect of musical talent. In them the syrinx 

 is of an entirely different and much simpler form. 



' The foot of a swallow is, though comparatively small and feeble, 

 that of a true percher. It is covered with sadella, or scales, and has 

 the power of moving the hind toe independently of the other toes ; 

 this is indispensible for the grasping of a perch. The swift's foot, 

 unlike that of all other birds, is covered with smooth skin. The hind toe is 

 lacking in the power of independent motion, and in some of the genera 

 is turned forward alongside the others, instead of having an opposing 

 action like a thumb. Accordingly the posture of a swift when at rest is 

 either clinging to a vertical surface or squatting flat upon a level 

 one ; whereas, a swallow ^^B.y often be seen perching on a twig or 

 wire. 



' Lastly the swifts and hummingbirds have ten primary feathers in 

 the wing and ten in the tail, while the swallow and the singing perchers 

 have only nine in the wing but twelve in the tail.' 



For these reasons, then, among others, the swifts have been removed 

 from their. old proximity to the swallows, and grouped with the hum- 

 mingbirds and the goatsuckers, or nighthawks, under an order called 

 the Macrochires, or long-handed-ones, in allusion to the great length, 

 comparatively, of the outer joint of the wing, corresponding to the hand 

 in man. 



The Cypselidfe are world-wide in their distribution, species of one or 

 more of their six genera being found in every continent and in Aus- 

 tralia, all remarkable for their wonderful power of flight and for their 



