﻿EXTERNAL ANATOMY. SWIMMING FEET. 1 59 



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 with ease upon the snow, whatever may be its 

 depth beneath. The foot of the rails (Rallidce), 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 {Rallidce) is the scan- 

 sorial group of the Grallatores, and equally represent 

 the Cracidce.* 



(137.) For a swimming, or natatorial foot, we have 

 been prepared by the genera Phalaropus, Fnlica, and 

 Podoa : the last of which is perhaps the connecting fink 

 between the RallidcB and the Anatidce, or ducks: the long 

 legs, however, of the waders 

 are still continued to the Fla- 

 mingo, the most aberrant type 

 of the circle of the Anatidce, 

 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 the 

 Anatine circle. The typical 

 form of a natatorial foot is to 

 have the tarsus very short, the 

 three anterior toes lengthened, and united by a mem- 



* Fig. 86. c represents the bill of a most singular rail from Senegal ; 

 while tne hinder toe and claw (rf) does not differ in the least from that of 

 the generality of the species (b). It is our Rallus carinatus of the Ap- 

 pendix, and of the " Birds of Western Africa." 



