﻿122 ON THE CLASSIFICATION OF BIRDS. 



but there is no breadth of sole, the tarsus is much more 

 lengthened, and the toes, instead of being thick and 

 strong, are slender and weak. These birds never climb, 

 but as they sit much, and often very long, upon 

 branches, it is necessary their feet should be of such a 

 form as to enable them to preserve an equal hold on all 

 sides : we accordingly term their feet grasping. Next 

 come the trogons, whose toes are arranged quite dif- 

 ferently, although, like the last mentioned groups, they 

 have two before and two behind, but the latter are 

 perfectly posterior ; and as they are altogether inca- 

 pable, from the manner of their insertion, of being 

 moved from their ordinary position, the trogons might 

 be termed the only birds whose toes are absolutely in 

 pairs : they are, perhaps, the most sedentary birds in 

 creation, and hence their feet, which are also the 

 weakest, seem to be constructed for the sole purpose of 

 sitting still. We shall retain the appellation of Gressorial 

 to this form, the characters of which are, in addition 

 to the toes being disposed in pairs, that the two anterior 

 are by far the longest, and are connected together to 

 nearly half their length ; the two posterior being sepa- 

 rated, and the outer one nearly half the length of the 

 inner. 



(112.) The true Scansorial foot is seen only in the 

 woodpeckers. We must still consider these birds in 

 the same light as we have done the parrots, that is, in 

 having the toes placed in pairs ; for although the base 

 of the outermost seems to be on the same level with 

 that of the two which are anterior, this outer toe can- 

 not be brought even half way forward, at least in any 

 of the species we have examined in a fresh state, with- 

 out violence ; and, indeed, this latter faculty is not at 

 all required by the habits of these birds, for they never 

 use the foot either in feeding or in grasping. On flying 

 from one tree to another, the woodpecker generally 

 alights upon the upright stem, rather than upon an 

 horizontal branch, and immediately begins, in a per- 

 pendicular attitude, to explore the bark, and detect the 



