THE NATATORIAL OR AQUATIC FORM. 249 
and habits belonging to their kind. These families of 
beetles live only on fresh vegetables: they are diurnal, 
and sport in the glare of day, “‘ pure” in their food, 
elegant in their shapes, and beautiful in their colours. 
(308.) III. The characters belonging to aBERRANT 
groups, when viewed as a whole, for reasons already given, 
are too varied to admit of general application, further 
than that they depart much more from those which belong 
to pre-eminent types than these latter do from the sub- 
‘typical. It will, therefore, be necessary to consider aber- 
rant groups as naturally divided into three distinct types. 
We shall, for the present, distinguish these by the names 
which we have assigned to them in ornithology,—the only 
division of zoology wherein they have been accurately 
traced. It may be objected to this plan, that to desig- 
nate a type of quadrupeds or of insects by the same 
term as that which is appropriated to birds will lead to 
a confusion of ideas. But, on the other hand, as these 
types, throughout the animal kingdom, are found to 
present certain characters in common, the advantages of 
designating them by common names are abundantly 
obvious. Hereafter, when the subject has undergone 
deeper investigation, we shall suggest more compre- 
hensive and appropriate names. For the present, there- 
fore, we shall term them the Aquatic, the Suctorial, 
and the Rasorial: these, collectively, form the aberrant 
circle of every group in the animal kingdom. 
(309.) The nararorraLor AQuATIc types, represented 
by the natatorial order of birds, as the name implies, are 
more especially inhabitants of the waters. They possess 
many and striking peculiarities, modified, indeed, in the 
most astonishing manner, but more conspicuous, perhaps, 
throughout all natural groups than any of those be- 
longing to other types. We shall consider these cha- 
racters under the heads of structure and economy, and 
exemplify our remarks by some familiar instances. 
I. As to structure,—aquatic types are chiefly remarkable 
for their enormous bulk, the disproportionate size of 
their head, and the absence or very slight developement 
