362 



CHORD AT A. 



The smaller feathers are called coverts and contour 

 . feathers, according to their size and structure. The filo- 

 plumes are still smaller feathers, resembling hairs, with a 

 thin shaft terminating in a very small vane. They can be 

 seen still attached to the skin after plucking. The scales 

 on the legs and claws are epidermic and closely similar to 

 those found in the reptiles. 



After plucking, the skin may be removed from the 

 ventral surface by a median incision from head to cloacal 

 aperture (see Plate VIII.). The greater part of the body 



Fig. 257.— View of Respiratory Organs of the 

 Pigeon. (Slightly Diagrammatic.) 



Trachea. 



Clavicular-Sac. 



The median sac is the interclavicular. 



is seen to be occupied by the " breast," a mass of muscles 

 lying on the large sternum. The central keel (or carina) 

 of the sternum may be seen in the middle line. The 

 pectoral muscle can be cut away from its point of origin 

 along the sternum and clavicle, and thence forward. It 

 is inserted into the large deltoid ridge of the humerus. 

 It is evident that on contraction this muscle will depress 

 the wing. Under it lies the subclavian muscle, originating 

 from the sternum and passing upwards by a tendon which 

 can be followed through a foramen in the shoulder-girdle, 

 called the foramen triosseum, on to the upper side of the 



