202 AFFINITIES AND GEOGRAPHICAL 



the world, antecedent to a time of cultivation, were wholly 

 covered with marshes. On came the tide of population behind ; 

 it behoves them to spread landward for subsistence. The con- 

 sequence was a modification of the hitherto natatorial forms of 

 these birds, to suit a strolling life upon soft sand sand in 

 marshes. The webbing of the toes shrunk, being no longer 

 required for swimming ; the toes were elongated, so as to give 

 support upon a yielding ground or bottom ; the tarsi were 

 also lengthened, to raise the body of the bird above the shallow 

 water in which it walked : at the same time the animal ac- 

 quired a greater length of neck and of bill to enable it to feed 

 in these waters. The result is the Wading Birds (Gfrallatores 

 of Cuvier) ; merely a transformation of their swimming pro- 

 genitors. In some parts of the earth, however, the regions 

 adjacent to the sea were not marshes, but extensive sandy 

 plains, presenting means of subsistence somewhat scantier, 

 but still not to be neglected. The consequence was a branch 

 of the swimmers, adapted by length and strength of limbs for 

 that rapid progression from one place to another which is re- 

 quired by animals placed on extensive wastes. This branch 

 comprises the Running Birds (Cursores), the Ostrich in Africa, 

 the Emeu and Cassowary of Australia, the Khea of America, 

 the Apteryx of New Zealand ; characterized by an extinction 

 of the hind toe, which is not needed in their field of existence, 

 and a reduction of the wings for the same reason in a modified 

 degree, with, however, an approximation to mammalian cha- 

 racters, in the hair-like appearance of the feathers, the presence 

 of a diaphragm in the visceral cavity, and other structural 

 minutiae. 



The three subdivisions of the first stirps are with tolerable 

 distinctness seen, passing each into its several progeny among 

 the waders. Looking at once to external features, and to habits 

 and characters, we readily select, as the descendants of the 

 anatine birds, the Ardeidce (Herons, Spoonbills, and Storks), 

 the most brilliantly plumaged of the Waders, as the Ducks are 

 of the Swimmers, and equally addicted to a foul kind of ani- 

 mal diet, being, as is well known, amongst the most active 

 scavengers of eastern and other cities. The anserine birds 

 claim a progeny in the Gruidce (Cranes), whose form of head, 

 and the position of the eye, as well as the elevation of the hind 

 toe upon the leg, remind us of that family, while their con- 

 stancy to a pure vegetable diet is equally conspicuous. The 

 Phalleropes, Gallinules, and Coots, reappear in a variety of 



