CLASS II. BIRDS. 55 



and a doubt still exists if it be not oviparous. This is the 

 belief of the inhabitants of New Holland, who assert that it 

 Jays two eggs; and the dissection of the animal has led to 

 the opinion that the eggs, if not laid, are hatched within the 

 body of the parent, by its own heat, but just before the birth 

 of the offspring. The male has, upon each of its hind feet, 

 a spur, perforated by a small canal, through which, it is said, 

 it can eject a poisonous fluid when it inflicts a wound. It is 

 an aquatic animal, inhabiting the rivers and marshes of New 

 Holland. Its feet are webbed, to adapt it for swimming. 



SECTION III. 

 Class II. Birds. 



BIRDS being intended for flight, Nature has adapted the 

 structure of their organs to this purpose. Their anterior 

 extremities, being designed to support them in the air, serve 

 none of those purposes to which they are applied in quad- 

 rupeds ; and they therefore invariably stand and walk upon 

 two feet only. The neck is long, and capable of a great 

 variety and extent of motion ; and the mouth, being furnished 

 with a hard, horny beak, is without teeth. The breast-bone 

 is very large and strong, in order to support the powerful 

 actions of the wings, and has in front a large projection, in 

 shape like a keel, that serves for the attachment of the strong 

 muscles which put the wings in motion. The wings are 

 composed of nearly the same number and kind of bones as 

 the anterior extremities of quadrupeds, and are covered witli 

 long and wide feathers or quills, so arranged as to be capable 

 of acting upon the air, raising the animal from the ground, 

 and conveying it about from place to place. The tail is also 

 furnished with feathers that may be stretched out in the 

 form of a fan, and serve to balance and direct the flight. The 

 feet are furnished generally with four claws, but sometimes 

 with only three. The bones of the leg and thigh resemble 

 very nearly those of quadrupeds. 



The heart of*birds is constructed, like that of the Mamma- 

 lia, with four cavities, two auricles and two ventricles. They 

 have, of course, a double circulation, one through the lungs, 

 and the other through the body. Their lungs, however, are 

 arranged differently. They are fixed against the back and 

 sides of the body, and covered by a membrane, which, being 



