THE NATATORIAL OB 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 NATATORIAL or 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 



