EXTERNAL ANATOMY. 
■SWIMMING FEET. 
159 
themselves sink, and plunge any other sort of bird into 
the water not one third the weight of the jacana ; who 
thus appears, at a distance — where its fragile support is 
not seen — to walk upon the surface of the lake. It is 
precisely upon this principle that the snow shoes of the 
Canadians are constructed, by which they are enabled to 
walk wdth ease upon the snow, whatever may be its 
depth beneath, 'fhe foot of the rails (Uullidw), whose 
habits lead them to the edges of muddy ponds, and who 
habitually live in marshes and swampy grounds, exhibit 
a subdued modification of the same structure : the toes 
are remarkably long; but as these birds roost upon the 
low boughs which overhang the water, and even in trees 
eight or ten feet from the ground, their claws (fig-. 86 . b) 
are consequently small in comparison, and sufficiently 
curved to render them instruments of prehension. It is 
quite evident that this family is the scan- 
sorial group of the Grallatores, and equally represent 
the Cracidm* 
(137.) I’or a swimming, or natatorial foot, we nave 
been prepared by the genera Phalaropus, Fulica, and 
Fodoa: the last of which is perhaps the connecting link 
between the RaMda and the Anatidai, or ducks: the long 
legs, however, of the waders 
are still continued to the Fla- 
minyo, the most aberrant type 
of the circle of the Anatida, 
to which, in every other re- 
spect, it has an intimate and 
unquestionable affinity, as will 
subsequently more fully ap- 
pear when we come to tlie 
Anatine circle. The typical 
form of a natatorial foot is to 
have the tarsus very short, the 
three anterior toes lengthenod, and united by a mem- 
» Fin. 86. c represents the bill of a most singular rail from ^“8^1 j. 
while the hinder toe and claw (d) does not ditt'er in the least tro 
the generality of the species (6). It is onr Halim carinatus oi cne Ap- 
pendix, and of the “ Birds of Western Africa.” 
