404 DISSECTION OF THE PIGEON 



down the floor of the mouth so as to expose the cavity fully. 

 Note the following structv/res. 



1. The posterior narial apertures are a pair of long narrow 



apertures, lying side by side in the roof of the 

 mouth. The anterior two-thirds of their length are 

 hidden by a pair of prominent folds of the mucous 

 membrane of the palate. 



2. The aperture of the Eustachian tubes is a median open- 



ing, behind the posterior narial apertures. 

 Pass a bristle through the aperture, and, along the right 

 and left Eustachian tubes to the tympanic comities. 



3. The tongue is triangular, ending in front in a sharp, 



forwardly directed point ; and produced behind into 

 a pair of backwardly directed processes, fringed with 

 fine horny papillae. 



4. The glottis is an oval aperture, with tumid lips, in the 



floor of the mouth, just behind the tongue. 



5. The entrance to the oesophagus is large and wide, and 



situated behind the glottis. 



B. The Abdominal Viscera in situ. 



Lift up the hinder end of the sternum, and cut through 

 its sides about midway between the dorsal and ventral su/rfaces. 

 Gut through the coracoids and clavicles about the middle of 

 their length. Detach the sternum with a scalpel from the 

 underlying parts, and remove it entirely. 



1. The falciform ligament is a median vertical sheet of 



peritoneum, connecting the dorsal surface of the 

 sternum with the underlying viscera : it is continuous 

 in front with the pericardium, and behind with the 

 omentum. 



2. The heart, which is still enclosed iu the pericardium, is 



large and conical, with the apex directed backwards. 

 It lies in the anterior part of the thorax. 



3. The lungs are spongy bodies lying at the sides of, and 



dorsal to, the heart, and very largely concealed by it. 



4. The liver is a solid, lobed organ, of a dark-red colour, 



lying behind, and at the sides of, the heart. 



