that connect the Orders and Families of Birds. 409 
it at some distance from the Owls, in which the same members 
are comparatively strong; while the wide gape of its mouth serves 
to divide the families still further*. A connecting link has been 
however supplied by an Australasian group, the Podargus of 
M. Cuvier, which harmonizes these discrepant characters. We 
have an opportunity of observing among the specimens in the 
collection of the Society, how far the bill of this extraordinary 
genus combines the different forms of that of the two genera, and 
how far the legs, still maintaining the characteristics of Caprimul- 
gus, such as the unequal length of the toes, are related to those of 
Strix by their superior robustness. Here, indeed, there is a beau- 
tiful gradation of affinities. All the front toes of Caprimulgus are 
united by a connecting membrane as far as to the first joint: those 
of Strix are divided to the origin ; while those of Podargus par- 
take of the characters of both, in having the middle toe connected 
which the serration can be applied. "There are many other groups of birds, possessing 
the same character, to which the same application of it can never be assigned. We 
may observe, for instance, that the greater part of the genus Pelecanus of Linnæus pos- 
sess this character. This group of the Natatores meets the Birds of Prey, as we shall 
have occasion to observe hereafter, on the opposite side of that circle which embraces 
the whole class : and thus on both sides of the order we find a similar construction 
in the groups immediately approaching it. Many of these birds, whose feet are natu- 
rally ill adapted by their webbed structure for laying hold of any object, are yet found 
to incubate among trees, where the serrated claw may give them a firmer power of - 
prehension: they are also asserted to seize their prey occasionally by the foot; in 
which act the structure of the nail, as in the case cited from Mr. White respecting 
the Caprimulgus, may be peculiarly useful.—See p. 418. Notes * and +. The family 
of Ardeide among the Wading Birds equally exhibit an analogous construction in 
the middle nail. Here, again, this character seems adapted to their mode of life in 
enabling them to hold their prey more firmly in those slimy and muddy situations 
where it might otherwise elude them : while, at the same time, it may assist their feet, 
(which, like those of the Pelecanide, are naturally ill suited for grasping,) in their hold 
among the trees, where, like some also of the latter family, they build their nests. 
* « Rostro minimo nigro, Rictu oris ingenti, Pedibus brevibus exilibus ab aliis qui- 
buscunque Noctuis abunde distinguitur." Rai Syn. Av. p.27. 
with 
