8 ZOOLOGY. 



Libellula {jyl. T-l, Jig. 44) ferruginca occurs from Spain to Java. Peltis 

 pusilla, a coleopterous insect, inhabits China, Madagascar, and Brazil. 



Tlie brightest colored and the larger forms of animal life are generall}'- 

 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 specie's of fish to leave rivers in 

 othej 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 vertebras, whence the animals provided 

 Avith it are named Yertebrata ; 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 Yertebrata 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 withj^Z. 74, represents 

 the oi'ders 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 Yertebrata lies in 

 the nervous system, which is not developed as a brain and spinal marrow, 

 but as a nervous ring round the oesophagus, 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 

 Radiata, Mollusca, and Articulata. 



The Kadiata are named from the arrangement of the parts around an 

 axis somewhat as in plants, whence they are also called Zoophyta. The 

 Mollusca or soft animals, which include the shellfish, are characterized by 

 the soft pulp3^ 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 

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