Mammijhous Animals, 511 



sequent classes. The class of mammiferous animals ought to 

 be placed at the head of the animal kingdom, not only because 

 it is the class to which we ourselves belong, but because it is 

 that which possesses the most numerous faculties, the most 

 delicate sensations, and the greatest variety of action, and in 

 which the assemblage of all their qualities appear so combined, 

 as to produce an intelligence more perfect, more fertile in 

 resources, less the slave of instinct, and more capable of pro- 

 gressive perfection, than what is found in any of the other 

 classes. 



As the quantity of respiration in mammiferous animals is 

 comparatively moderate, they are generally constituted for 

 walking firmly, with a continued motion, and all the joints of 

 their skeletons are fitted with a precision which determines 

 the regularity of their movements. Some animals of this class, 

 however, are able to raise themselves in the air by the aid of 

 membranes extended on the prolongation of their members, 

 of which the common bat furnishes a well known example. 

 Other animals of this class have their limbs so shortened and 

 contracted, that they can only move with ease when in water. 

 Cetaceous animals, as whales and seals, afford instances of 

 such a formation ; but they do not on this account lose the 

 general character of mammiferous animals. 



In all animals of this class the upper jaw is fixed to the 

 cranium, or skull ; the lower is composed of only two pieces, 

 and is articulated by a prominent joint or condyle (from the 

 Greek Jwndylos, a knuckle) to the temporal bone. The neck 

 is composed of seven vertebrae, except in one species, which 

 has nine. The head of mammiferous animals is always arti- 

 culated by two condyles to the first vertebral bone called the 

 atlas. Their tongue is always fleshy, and attached to a bone 

 called hyoides, which is composed of smaller pieces, and is 

 suspended to the skull by hgaments. Their two lungs are 

 divided into lobes, composed of an infinite number of cells, 

 and are always enclosed, without adherence, in a cavity formed 

 by the ribs and the diaphragm. Their organ of voice is always 

 at the upper extremity of the trachea or windpipe. 



Their residence, being on the surface of the earth, exposes 

 them less to alternation of temperature than many of the ani- 

 mals in the other classes. Their bodies have only a light co- 

 vering of hair, which is generally very thin in warm climates. 



Cetaceous animals, which live entirely in water, are abso- 

 lutely without hair. 



In all mammiferous animals, the generation is essentially 

 viviparous ; and, as before stated, they nourish their young 

 with their milk. There has, however, been one singular ani- 



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