VERTEBRATA. 



VERTEBRATE animals are characterized by having 

 the brain and principal trunk of the nervous system 

 included in a bony articulated case, composing the 

 skull and vertebral column. They have all red 

 blood, and a muscular heart. The mouth is fur- 

 nished with two jaws moving vertically. They have 

 distinct organs of sight, hearing, smell, and taste. 

 The limbs are never more than four in number. 

 The sexes are in all cases separate. 



They are divisible into the following five classes : 



* With warm blood: heart with two auricles and 

 two ventricles. 



I. MAMMALIA Viviparous animals, suckling their 



young : breathing by lungs. Body generally covered 

 with hair, and furnished in most cases with four 

 feet. 



II. AVES Oviparous animals; breathing by lungs. 



Body covered with feathers ; furnished with two 

 wings and two feet. 



A 



