18 THE ANIMAL KINGDOM. 



held analogous to the brain, is but little larger than the others. 

 The covering of the body is divided by transverse folds into a 

 certain number of rings, of which the teguments are in some 

 hard, in others soft, but to the interior of which the muscles are 

 always attached. Articulated limbs are often attached to the 

 sides of the annulated portions of the trunk, but it is also frequent- 

 ly destitute of those organs of movement. To these animals 

 Cuvier has given the name of ARTICULATED ANIMALS, (Ani- 

 malia Articulata.) 



In this division is observed the transition from the circulat- 

 ing system in closed vessels, to a nutritive process by simple 

 imbibition ; and also a corresponding transition from respiration 

 by circumscribed organs to respiration performed through the 

 medium of tracheae or air-vessels dispersed through the body. 

 The organs of taste and sight are very evident in the animals 

 of this division. Their jaws, when they have any, are invaria- 

 bly lateral. One family alone possesses the organ of hearing. 



The animals comprehended under the fourth general form 

 are usually known under the name of Zoophytes. They ap- 

 proach in structure to the homogeneous character of plants. 

 Neither a distinct nervous system, nor particular organs of sense, 

 are perceptible, and but obscure vestiges of circulation. Their 

 respiratory organs are almost always on the surface of their bo- 

 dies. The intestines of the greater number consist merely in a 

 cavity without an outlet. The lowest in the series, which are al- 

 so the last of the animal tribes, exhibit nothing but a homoge- 

 neous pulp, possessed of motion and sensibility. In the preced- 

 ing divisions the organs of movement and sense are disposed 

 symmetrically on both sides of an axis ; but in this they have a 

 circular arrangement round a common centre. This form of 

 existence Cuvier arranges under the head of RADIATED ANI- 

 MALS, (Animalia Radiata.) 



The term Zoology includes the whole of the Animal kingdom; 

 besides which different departments have received particular 

 names, such as Ornithology for the birds, Ichthyology for the 

 fishes, Entomology for insects, and Conchology for the testa- 

 ceous Mollusca. 



