38 ANIMALIA VERTEBRATA, 



CLASS I. 



MAMMALIA. 



The mammalia are placed at the head of the animal kingdom, 

 not only because it is the class to which man himself belongs, 

 but also because it is that which enjoys the most numerous 

 faculties, the most delicate sensations, the most varied powers 

 of motion, and in which all the different qualities seem com- 

 bined in order to produce a more perfect degree of intelli- 

 gence, the one most fertile in resources, most susceptible of 

 perfection, and least the slave of instinct. 



As their quantity of respiration is moderate, they are de- 

 signed in general for walking on the earth, but with vigorous 

 and continued steps. The forms of the articulations of their 

 skeleton, are, consequently, strictly defined, which deter- 

 mines all their motions with the most rigorous precision. 



Some of them, however, by means of limbs considerably 

 elongated, and extended membranes, raise themselves in the 

 air 5 others have them so shortened, that they can move with 

 facility in water only, though this does not deprive them of 

 the general characters of the class. 



The upper jaw, in all of these animals, is fixed to the cra- 

 nium ; the lower is formed of two pieces only, articulated by a 

 projecting condyle to a fixed temporal bone; the neck con- 

 sists of seven vertebrse, one single species excepted which has 

 nine ; the anterior ribs are attached before, by cartilage, to a 

 sternum consisting of several vertical pieces; their anterior 

 extremity commences in a shoulder-blade, that is not articu- 

 lated, but simply suspended in the flesh, often resting on the 

 sternum by means of an intermediate bone, called a clavicle. 



