8 ZOOLOGY. 
Libellula (pl. 74, fig. 44) ferrugimea occurs from Spain to Java. Peltis 
pusilla, a coleopterous insect, inhabits China, Madagascar, and Brazil. 
The brightest colored and the larger forms of animal life are generally 
found in the warmer zones, as the large crocodiles and gigantic serpents 
among reptiles, and the lions and tigers among cats. There are, however, 
some exceptions, as some of the largest whales inhabit cold climates, whilst 
the American mastodon was larger than any recent elephant. 
Man exercises considerable influence upon the distribution of animals. 
Cultivation, and the removal of forests, together with hunting and fishing 
upon a large scale, drive them to other localities, and reduce their numbers ; 
whilst steam navigation causes certain species of fish to leave rivers in 
other respects well adapted to them. For his own use, man transports 
various domestic animals, some of which, like the horse and ox in South 
America, have formed large wild herds. Goats and dogs occur similarly in 
certain islands. Some animals have been so long domesticated, that the 
original stock is unknown, if it still exists, as in the case of the cat and 
camel. 
The animal kingdom is usually separated into two large sections by the 
presence or absence of an internal skeleton; a separation, however, which 
is not natural, as the two sections are not of equal value, as will appear 
when we speak of the divisions. The essential part of such a skeleton is 
the spine, composed of a series of vertebrae, whence the animals provided 
with it are named Vertebrata; and those without it Evertebrata or 
Invertebrate animals. The latter section is much the richest in genera and 
species ; it is separated into three great divisions (the Vertebrata forming 
another) and many minor groups; and, from the difficulty which they 
present, there still remains a good deal of uncertainty in the classification 
of certain portions. The following sketch, together with pl. 74, represents 
the orders according to the classification of Cuvier somewhat modified, and 
generally in inverse order. 
Instead of an internal skeleton, many of the evertebrate animals are 
provided with a kind of external skeleton for the protection of the inner 
soft parts. The chief distinction between them and the Vertebrata lies in 
the nervous system, which is not developed asa brain and spinal marrow, 
but as anervous ring round the cesophagus, or as a double chord, with bead- 
like swellings at various intervals, as if the brain were divided into different 
centres of vitality, giving rise to various nerves. Hence, in dividing an 
insect into several parts, each seems to have nearly the same amount of 
vitality. .Cuvier divides this section into THREE Divisions, which are named 
Rapiata, Mortiusca, and ARTICULATA. 
The Radiata are named from the arrangement of the parts around an 
axis somewhat as in plants, whence they are also called Zoophyta. The 
Mollusea or soft animals, which include the shellfish, are characterized by 
the soft pulpy and slimy nature of the body, which is inclosed in a kind of 
mantle; they.are generally without regular limbs, and some are without a 
head. Their power of locomotion is generally limited, and some are 
altogether sedentary. The Articulata are distinguished by a ringed or 
212 
