ANISODACTYLI. 343 



leaves, and others are to be sought for in the corollas 

 of plants, into which they have plunged for the sake 

 of the sweet juices which accumulate there. 



Birds of this family bring us to the margin and 

 surface of the waters, with those races whose habit 

 it is to prey on the wing ; but there are still those 

 tribes which feed chiefly by perching on the stems 

 or the twigs of trees, or walking on the ground ; and 

 we shall find that, though there are great differences 

 in the sternal apparatus, both of those which have 

 the one habit and those which have the other, ac- 

 cording as they combine it more or less with the 

 action of the wings, yet there are characters descrip- 

 tive of each, that run through the whole. 



STERNA OF THE ANISODACTYLI. 



Some birds included in this order use the wings 

 more and some less, but as they are all more 

 or less walkers on the boles of trees, and other sur- 

 faces, on which, from their form, and especially from 

 their position, there can be but little stability arising 

 from the ordinary pressure of gravitation, which is 

 the principal means of stability upon horizontal sur- 

 faces, they require to be birds of very ready wing, 

 which can instantly throw themselves upon that part 

 of their organisation, in the event of their claws miss- 

 ing hold. The wing required for this purpose must 

 have muscles of considerable power, and also firm 

 feathers. Such wings have to be used in all positions 

 of the body ; sometimes both, and at other times only 

 one of them can act, and they often strike against 

 trees, branches, and other hard substances, so that 

 they require more strength in their whole structure, 

 than wings which are used only in the free air. 



Some of these birds also feed on the wing, and 



