120 
ON THE CLASSIPIOATION OF BIBOS. 
short, yet perfectly formed. Now it deserves especial 
attention that all groups which represent the Struthi- 
onidte in other circles, either have the fewest number 
of toes, or their disposition is variable ; as if this was 
the point in the circle where these members changed 
their character, and number, even in the genera. Hence 
it is that the whole of the typical Grallatorial birds have 
the hind toe so short, that it may be termed obsolete. 
By the same law we find nearly all the Charadriadce, 
or the plovers (the most aberrant of the GmlUitores), 
with only three toes, like most of the ostriches, which 
in every thing else they symbolically represent. Thus, 
also, we account for the disappearance of the hinder toe 
in the sub-genus Apte.rnus, or the three-toed wood- 
peckers, — the variation of the .structure of the foot, 
among the Ilalcyonida;, or kingfishers, — and in the Mu- 
sophugidce, or plantain-eaters, one genus of which 
(Coliuit) has all the four toes placed forward. Rach 
and all of these groups represent the StmthionideB in 
their respective circles, in which they are the most 
aberrant. We may now proceed to the variations of 
the toes in regard to situation. 
(110.) The toes vary in *their position no less than 
in their number, even in such birds as have only three. 
The direction of these members, in cursorial or three- 
toed birds, is forward, and their divisions are mostly 
cleft to the base ; but in the three-toed woodpeckers, 
where the hallux is wanting, one of those which are 
versatile, and which is generally 
called the exterior hind toe, is di- 
rected more backwards than usual ; 
so that there are two before, and 
one behind. The usual structure 
of the kingfishers is to have three 
anterior, and one posterior toe (Jig. 
63 . «) ; but in such as have only 
three it is the inner anterior toe 
which disappears, so that the hallux, 
which is wanting in Apternus, re- 
mains in the sub-genus Ceyx, (b. 6.) 
