420 CORACIIFORMES 



grouped together by Nitzsch as Macrocltires (long-hauded forms) 

 from the length of their manual bones, though really the parts 

 of the wing nearer the body are proportionally most elongated. 



Swifts certainly differ from Humming-birds in the broad, flat 

 skull, the short curved bill, and the extremely wide gape, besides 

 their comparatively sombre coloration ; but these facts cannot be 

 allowed to militate against an alliance so strongly confirmed by 

 many points of structure, while nothing but the pardonable 

 ignorance of former times caused the Family to be united with 

 their Passerine analogues, the Swallows. The Cypselidae agree 

 with the Trochilidae in the number and colour of their eg-gs, 

 and the extraordinarily deep keel of the sternum, which, with 

 the long wings, gives so great a power of flight. 



Fam. XI. Cypselidae. — Of this group three Sub-families may 

 be recognised, (1) Macropteryginae, (2) Chaeturinae, and (3) 

 C]/2}sclinae. 



The short but robust metatarsi are scutellated anteriorly, the 

 scales being nearly obsolete in the Chaeturinae ; fairly powerful 

 claws terminate the free toes, which are all directed forwards in 

 the Cypselinae, though the hallux is somewhat laterally inclined 

 in Fanyptila, and is said to be occasionally versatile in the 

 other Sub-families. The middle and outer digits in the Cypse- 

 linae have the further peculiarity of possessing only three joints, 

 while the metatarsi or even the toes are feathered. The ten pri- 

 maries, and especially the exterior, are extremely long, with thick 

 narrow outer webs ; the short secondaries vary from six to eight. 

 The square or forked tail has ten rectrices — not uncommonly 

 rigid and pointed — as against twelve in Swallows. The furcula 

 is U-shaped; the tongue sagittate; the syrinx tracheo-bronchial 

 (the muscles not being inserted on the bronchial rings) ; the 

 aftershaft is large or small; the adults have a little blackish 

 down on the unfeathered spaces ; the nestlings are blind and naked. 



The coloration is usually greenish -black or mouse -brown, 

 occasionally with a white chin, breast, or rump ; a rufous collar 

 or chestnut ear-coverts occur in Macropteryx and Cypselo'ides, 

 where alone the males differ from the females, and the young 

 from both. The Family ranges over the whole world, with the 

 exception of the extreme north and south, New Zealand and 

 some other islands ; the six genera containing about eighty species 

 varying in size from about four to fourteen inches. 



