132 
GENERAL OENITHOLOGY. 
have a narrow membranous margin running the whole length. The same thing is evident in 
a great many waders, and on the free borders of the inner and outer toes of web-footed birds. 
In the grouse family 
{Tetraonidce), mar- 
ginal fringes are 
very conspicuous ; 
there being a great 
development of hard 
horny substance, 
fringed into a series 
of sharp teeth or 
pectinations (fig. 
35). These forma- 
tions appear to be 
deciduous, that is, 
to fall off periodically, hke parts of the claws of 
some quadrupeds (lemmings). 
Fig. 52. — Totipalmate foot of a 
pelican; reduced. 
Fig. 53. — Lobate foot of a coot ; reduced. 
Fig. 53 Us. — Lobate foot of pbala 
rope, Lohipes hyperboreiis ; nat. size. 
Claws and Spurs. — With rare anomalous exceptions, as in the case of an imperfect 
hind toe, every digit terminates in a complete claic. The general shape is remarkably constant 
in the class ; variations being rather in degree than in kind. A cat's claw is about the usual 
shape : it is compressed, arched, acute. The great talons of a bird of prey are only an en- 
largement of the typical shape ; and, in fact, they are scarcely longer, more curved, or more 
acute than those of a delicate canary bird ; they are simply stouter. The claws of scansorial 
birds are very acute and much curved, as well as quite large. The under surface of the claw 
is generally excavated, so that the transverse section, as 
well as the lengthwise outline below, is concave, and the 
under surface is bounded on either side by a sharp edge. 
One of these edges, particularly the inner edge of the middle 
claw, is expanded or dilated in a great many birds ; in some 
it becomes a perfect comh, having a regular series of teeth. 
This pectination (Lat. pecten, a comb), as it is called, only 
occurs on the inner edge of the middle claw. It is beautifully shown by all the true herons 
{ArdeidcB) ; by the whip-poor-wills and night-hawks {CaprimulgidcBj fig. 41): by the frigate 
pelican (Tachypetes) ; and imperfectly by the barn owl (Aluco flammeus). It is supposed to 
be used for freeing parts of the plumage that cannot be reached by the bill from parasites ; 
but this is very questionable, seeing that some of the shortest-legged birds, w^iich cannot 
possibly reach much of the plumage with the comb, possess that instrument. Claws are 
more obtuse among the lower birds than in the insessorial and scansorial groups, as the 
columbine and gallinaceous (rasoriaV) orders, and most natatorial families. Obtuseness is 
generally associated with flatness or depression ; for in proportion as a claw becomes less 
acute, so does it lose its arcuation, as a rule. This is well illustrated by Wilson's petrel 
{Oceanites oceanicus), as compared with others of the same family. Such condition is carried 
to an extreme in the grebes (Podicipedidce) , the claws of which birds resemble human finger- 
nails. Otherwise, deviations from curvature, without loss of acuteness^ are chiefly exhibited 
by the hind claw of many terrestrial Passeres, as in the whole family Alaudidce (larks), 
and some of the finches {FringillidcB) , as the species of long-spur " {Centrophanes). But all 
the claws are straight, sharp, and prodigiously long, in birds of the genus Parra (fig. 
53 ter) ; these ja^anas being enabled to run lightly over the floating leaves of aquatic plants 
by so much increase in the spread of their toes that they do not slump in." Claws are 
