150 
SYSTEM OF NATURE. 
air, on trees, on tlie ground, or in the water, the quadruped and the bee¬ 
tle are alike gifted with the ability to seek it. If we pass from placentals 
to marsupials and birds, we shall find a similar diversity in food, and a 
similarly diversified mode of obtaining it.* If we proceed still another 
step, and compare the Carabina with the Ferina or Accipitrina, we shall 
find the analogy still holding good. The Dytiscites, the otters and the 
ospreys take their prey in the water; the Staphylinites, the hyaenas and 
the vultures seek for flesh in a state of putrefaction; the Cicindelites, 
the hawks and the tigers prey only on living animals; the Carabites, 
foxes and owls prowl about by night: we shall find similar analogies 
existent in the most minute ramifications of all the groups. Indeed the 
study of Natural History is a study of degrees or grades of difference. 
The Vertebrata and Pterota are distinguished from each other by a 
broad and marked structural discrepancy : their organs of support, cir¬ 
culation and respiration, are formed on different plans. The divisions 
of Vertebrata and Pterota are distinguished by minor differences, prin¬ 
cipally by the varied development of the four or ten organs of locomo¬ 
tion with which they are respectively provided. The first difference is 
one of internal structure; the second is rather the adaptation of struc¬ 
ture to diversified economy, as in placentals, birds, reptiles and fishes, 
or in butterflies, flies, bees and beetles. The subdivisions are distin¬ 
guished by what might be called sub-differences. In birds and butter¬ 
flies (Lepidoptera) these sub*differences occur chiefly in the mouth, legs 
and wings. By a little attention to these particulars equivalent divisions 
will be readily established, and universal order must result. 
* It should here he remarked that marsupials, birds, both classes of reptiles, both 
classes of fishes, also Lepidoptera, Diptera, Hymenoptera, Orthoptera, Hemiptera and 
Neuroptera, divide in a similar manner, the primary divisions of the fourteen classes being 
exact equivalents. 
LUXFORD Sc CO., PRINTERS, RATCLIFF HIGHWAV. 
