269 



SCANSORIAL OR CLIMBING FEET. 



The principal object to be accomplished by 

 these feet, is not simple adherence to an upright 

 overhanging surface, as in the case of the swallows 

 and swifts, or progressive motion along the boles 

 and branches of trees, as in that of the anisodac- 

 tyti. It is, in the more perfect specimens, motion 

 from branch to branch, and in the others stability on 

 the boles of trees, with the body in an upright position. 

 Feet which accomplish these purposes are all zygo- 

 dactylic, or yoke-toed, that is, they have the outer toe 

 very readily reversible, so that the foot presents two 

 toes to the front and two to the rear, both nearly of 

 equal power ; and where there is a different function 

 to be performed, that is done chiefly by modified arti- 

 culations of the other parts of the foot and leg. 



The extremes of this kind of foot are perhaps those 

 which are found in the woodpeckers and the parrots. 

 The woodpeckers are trunk birds, and when upon 

 trees, they are insectivorous ; the parrots, on the 

 other hand, find no food upon boles or large branches, 

 but subsist chiefly upon fruits, and ramble about 

 among the smaller twigs and sprays in quest of them. 



Thus, though both are climbers, they climb so very 



