134 
ON THE CLASSIFICATION OP BIBDS. 
thrushes possess very little of the first of these indica- 
tions, but the breadth of the claw is apparent in all their 
minor groups. Nature advances another step in the genus 
Partis, where, as we see in P. major, {fig. 70. o) the fore 
toes are very unequal in length, 
and the hinder, — as Linnaus 
well observes, — strong and 
large ; equal, in fact, to the 
middle toe. Now the Pari are 
well known arboreal birds, not 
only living among trees, where 
alone they seek their food, hut 
exploring the most slender 
branches and twigs in a man- 
ner almost peculiar to them- 
selves : these habits render 
them in some degree, climbers, 
and they have consequently, in the greater deve- 
lopment of the hind toe, one of the scansorial cha- 
racters. Let us now see how the same structure is 
developed, but under a totally different form, in a 
genus which belongs to the very same family. We 
allude to the Mniotilta varia, VieiUot, or black and 
white creeper of Wilson ; now this bird unquestionably 
belongs to the warblers, and yet it runs up the trunk of 
a tree almost with the same facility as a nuthatch ; the 
hinder claw (i) is consequently much more lengthened 
in proportion, than that of the titmouse, in order to 
support and keep the body in equihbrium, whereas the 
hind toe of the Pants is used for grasping, for the 
bird itself never climbs perpendicularly like the Mnio- 
tilta : it may, indeed, rather be said to hang than 
climb; and as greater strength of muscle is requisite 
for the first than for the last of these positions, we 
consequently perceive that the foot of the titmouse 
is much stronger than that of the Mniotilta, although 
the latter bird makes the nearest approach to legitimate 
climbing. 
(122.) Leaving these and similar representations of 
