200 VERTEBRATES. 



The Manati has no voice nor cry, for the only noise it makes 

 is by fetching its breath. Its internal parts somewhat resemble 

 those of a horse ; its intestines being longer, in proportion, than 

 those of any other creature, the horse only excepted. 



CHAPTER VIII. 



DIVISION I.— VERTEBRATES. 



CLASS II. — BIRDS. 

 GENERAL CHARACTERISTICS. 



Nature has ailapted the organic structure of Birds to the 

 purposes of flight. The long neck is capable of great extent and 

 variety of motion ; and the horny beak which is affixed to the 

 mouth, is destitute of teeth. The breast-bone, which is very large 

 and strong, in order to support the action of the wings, is supplied 

 in front with a large projection, for the attachment of those strong 

 muscles which put the wings in motion The wings, composed 

 of nearly the same number and kinds of bones as the anterior 

 extremities of quadrupeds, are covered with long and wide feathers 

 or quills, which are so arranged as to be capable of acting upon 

 the air, raising the bird from the ground, and conveying it from 

 place to place. The tail is furnished with feathers that may be 

 stretched out in the form of a fan, and serve to balance the animal, 

 as well as to direct its flight. The feet are generally furnished 

 with four claws, but sometimes with only three. The bones of the 

 leg and thigh are very similar to those of quadrupeds. 



Like the Mammalia, the heart of birds is constructed with 

 four cavities, two auricles, and two ventricles. Their lungs, which 

 are commonly called the sole, are affixed to the sides of the ribs 

 and back, and cannot be dilated or contracted to any great extent ; 

 but, to compensate for this seeming defect, Nature has furnished 



