252 FIRST PRINCIPLES OF NATURAL CLASSIFICATION. 
in any group which joined, and immediately blended into, 
the sub-typical (304.). We have seen that the feet 
are slightly, and often not at all, developed: an incapacity 
for quick motion is the natural result of such an organ- 
isation ; and hence it might theoretically be concluded 
that the feet are never used in the pursuit or capture of 
their prey. Now this is truly the case in numerous 
instances: natatorial types seize their food by the mouth 
alone ; and all such as do not swim, or pursue their 
prey by their wings, dart upon it from a fixed station, 
as if incapacitated to rove about in its search, like other 
animals, by the imperfection of their feet: the king- 
fishers, the herons, flycatchers, and innumerable other 
groups, are all well known instances of this habit, not to 
mention the whole tribe of Fissirostres among perching 
birds. The Cirripedes, or barnacles (the natatorial type 
of the Annulosa), and all others whose body is fixed, 
show us the same principle developed under a different 
aspect ; for here the habits of the animal at all times are 
so sedentary, that they seem absolutely incapable of 
moving from the spot where they complete their last or 
final change of form. The Hesperian butterflies (Hes- 
peride) are the most sedentary, in their larva state, of 
all true insects, for they fabricate and live in a little cell, 
formed by a leaf rolled into a cylinder. Every natural 
group, in short, contains some one representation of this 
type: we have not yet determined, however, whether ail 
internal feeders are of the natatorial (or apod) type. 
(312.) Let us now look for verifications of the fore- 
going theory among some of the best known animals ; 
all of which, in their own respective circles, belong to 
this type of form. First we have the whales, the 
leviathans of creation, before whose stupendous size 
even the elephant shrinks into moderate dimensions: 
the head is nearly as large as the whole body, the 
mouth is of vast size, and although a quadruped, it is 
apodal, or without feet. It lives in the waters, and the 
snout is so obtuse and blunt, that the extremity appears 
as if cut off. Next to these gigantic animals the hippo- 
