2232 THE BUSTARDS, THICKNEES, AND CRANES 



order, in that the nasal apertures of the skull are in the form of long slits (schizo- 

 rhinal); while they agree with the trumpeters in the absence of any notch in the 

 breastbone, and also in the presence of a very large aperture on the inner face of the 

 lower end of the metacoracoid. Their canon bone resembles that of the ducks (see 

 figure on p. 2089) and flamingoes, in that the fourth trochlea is much shorter than 

 the second a feature which at once distinguishes this bone from the correspond- 

 ing one of a heron or stork, in which the three trochlese are subequal (see figure 

 on p. 2054); and they differ from the bustards in the V-shaped furcula. In the 

 presence of bare tracts, some distance up the neck, the cranes approximate to the 

 trumpeters and rails; and they are further characterized by the oil gland being 

 tufted. Their plumage undergoes a double annual molt. 



Cranes are now represented by about sixteen species, of which the greater 

 number are confined to the Old World, while there are none in South America. 

 Geologically, they are a somewhat ancient group, as remains referred to the exist- 

 ing genus have been obtained from strata of Upper Eocene age. This harmonizes 

 with the view of Mr. Beddard, by whom cranes are regarded as the ancestral stock 

 from which originated the rails, the Limicolce, and most of the other birds treated of 

 in this chapter. It will, however, scarcely support his opinion that the herons are 

 likewise descended from the cranes, seeing that a member of the latter existed in the 

 London Clay, belonging to the lower part of the Eocene period; while it is scarcely 

 likely that the canon bone of the heron could have been derived from that of 

 a crane. 



Although the members of the family have been arranged under sev- 

 eral genera, it seems on the whole preferable to include all but the 

 crowned cranes in the typical genus ( Grus) . In the ordinary cranes the long and 

 straight beak is of moderate length, compressed and pointed, with the nostrils 

 placed in a groove near the middle, and partially closed behind by membrane; the 

 wings have the third quill the longest; a large part of the tibia is bare; the front of 

 the metatarsus is covered with scutes, and the toes are short, with blunt nails. 

 Generally there is a naked region about the eye and the base of the beak, while oc- 

 casionally the entire head may be devoid of feathers. They are birds of large size, 

 with the plumage either gray or white; and the elongation of the inner secondaries 

 into a kind of false tail, gives them a peculiarly-graceful appearance. Inhabiting 

 extensive plains and swamps, and endowed with a powerful and long- sustained 

 flight, most cranes are in the habit of performing migrations of great length. The 

 windpipe being lengthened and arranged in coils within a cavity in the breastbone 

 enables them to utter, when alarmed or on the wing, a loud trumpet-like call, which 

 is often audible at a distance of a couple of miles. Terrestrial in their habits, it 

 is said never perching on trees, all the cranes build on the ground; their huge 

 nests being placed in swamps, and the two or occasionally three eggs having a 

 greenish ground more or less spotted with reddish. 



The common crane (G. rinerea}, which some three centuries ago 

 P nested in the British Islands, where it is now but a rare visitor, is the 



typical representative of the genus, and is characterized by the mod- 

 erate length of the beak, which is high and sloping at the base, and straight in its 



