28 EXTERNAL PARTS 



The parts of legs which are bare of feathers need close 

 observation, as the kind and arrangement of the scaly covering 

 of these parts have much to do with the classification of 

 birds. The commonest arrangement is to have a distinct row 

 of squarish scales down the front of the tarsus, as in the Eng- 

 lish sparrow. Sometimes such a row is also found down the 

 back, as in most snipes ; occasionally there is found a row down 

 the outside of the tarsus, as in the flycatchers. These large, 

 squarish scales are called scxtella, and the tarsus is described 

 as scnteUate in front,' in front and behind,- or in front and along 

 the outer side,^ as the case may be. In the bluebird and in 

 some others these front scales are so completely grown together 

 as %o look like a continuous covering ; such a tarsus is said to 

 be booted.* In many cases a portion of the tarsus, and in the 

 geese the whole, is covered with small scales not very regularly 

 arranged. These seem to form a fine network, and portions 

 having such scales are said to be reticulate.'^ 



The scutellate portions are different from the reticulate in 

 another way. Scutella show as somewhat overlapping scales, 

 and the whole forms a solid covering, but the small scales 

 which form the reticulation are rather imbedded plates not 

 touching at their edges, and the covering is apt to be more 

 or less loose and ])liable; rarely, these plates are elevated at 

 their centers, and thus form tubercles, as in the fish hawk; 

 such a leg is said to be granulated.^ Sometimes a row of plates 

 of any kind will be so roughened, in a regular way, as to be 

 properly called serrated.*^ 



The toes are almost invariably scutellate along the top. The 

 tibia, when bare of feathers, has scales much like those of the 

 tarsus, and of course the same words are used for their descrip- 

 tion. In some cases this part is covered with loose skin with- 

 out any scales at all. 



