INTRODUCTION. 



21 



shoulder-blade, the humerus or arm, the cubitus or fore-arm, 

 and the hand, with the muscles and quills. The Posterior 

 Extremity consists of the femur or thigh, the tibia or leg, 

 the tarsus, or what is commonly but erroneously called the 

 leg, and the toes, with muscles and other parts. All these 

 parts, excepting the bill or anterior part of the jaws, the 

 .eyes, the tarsi, and the toes, are generally covered with fea- 

 thers, attached to the skin. 



Fig. 1. 



The Bill is composed of two mandibles, an upper, 1, and 

 a lower, 2, formed of horny substances ensheathing the jaws. 

 In the upper mandible are distinguished the base, the ridge, 

 of which the outline is named the dorsal line, the sides, the 

 edges or margins, and the point. In the lower mandible are 

 seen the base, the two crura or branches, their junction or 

 the angle, the ridge and its dorsal line, the edges, and the 

 point. 



