CLOTHING FEATHERS. 91 



The feathers on the under parts are distinguished 

 as those on the breast, the flanks, the centre of the 

 belly, the thighs, and the vent. But some of these 

 names must be understood with limitations. Thus 

 what are usually called the thighs are in reality the 

 legs of the bird, the thigh bones being to a consider- 

 able extent imbedded in the muscles, and capable of 

 but little motion, except in those species which have 

 great action in their feet. That which is called the 

 belly of a bird also requires explanation ; for it does 

 not, even in any of the species, answer to the soft ab- 

 domen to which that name is given in the mammalia; 

 and in swimming birds the sternum and ribs extend 

 so far backward as that a portion at the vent only, of 

 a size sufficient to allow the expulsion of the eggs, is 

 unprotected by bones. 



The feathers of the under part are, generally speak- 

 ing, smaller in size, and softer and more downy in 

 their texture than those on the upper part. The 

 differences of character indicated by them are not so 

 great or at all events not so striking as those indicated 

 by the upper part. In general, however, there is the 

 same gradation from the more perfect air birds to 

 the more perfect swimmers, the last of which, espe- 

 cially those which inhabit the colder seas and do not 

 migrate far toward the equator in winter, abound in 

 down of the finest description. This down consists 

 partly of a second feather produced at the end of the 

 barrel or tubular part of the principal one, and partly 

 of a separate clothing, each particle of which has its 

 own insertion in the skin, and which has no distinct 

 shafts, or any of the common characters of feathers. 

 This down, whether produced on the feather or on 

 the skin, is always frizzly or flocculent, as well as soft. 

 It thus has no general direction, like the feathers, 



