114 Mammalia. Respiratory System. 



7. Species that are Micfe. 



Of the Eodentia, the Porcupines are mute, save at the rut, when 

 the male emits a low grunt. 



Of the Artiodactyla, the Giraffe is mute, save at the sexual seasoD. 



The Marsupialia as a rule have little or no voice. 



8. The Trachea, &c. 



Rings ossified. 



In Ornithorhyncus the bronchial annuli are bony. 



Eings not closed anteriorly. 



Cete. In the BalcenidcB the rings are interrupted by a membranous 

 portion on the anterior surface ; a peculiarity which is unique 

 among Mammals. 



Bings are complete 



in some Perissodactyla {e^g. Horse), Artiodactyla {e.g. Ruminants)^ 

 Cete, and Marsupialia. 



Kings overlap 

 in most Sectorialia. 



Trachea convoluted. 



In-Enamellata. In Bradypus tridactylus the trachea is convoluted 

 as in the Nilotic* Crocodiles ; it descends nearly to the diaphragm, 

 and then curves upwards again before it divides into the two bronchi. 



Trachea divided ly median senium. 



Modentia. In the Cape Jerboa (Helamys) is found a tracheal 

 structure recalling the early division of the tube in Reptiles ; the 

 Trachea being divided a littlebeyo i i the Larynx into two canals by 

 a median septum; as if the bronchi began there, and were continued, 

 adhering, some way before diverging to the lungs. 



Trachea divides into three m'<in bronchial trtcnh 



in most Artiodactyla {i.e. Ruminantia and Hog) and in the Cefe. 



Bronchi with spiral coils. 



Sirenia. In the Dugong the cartilages of the bronchial tubes are 

 continued spirally into one another. 



9. The Lungs. 



Simple and undivided 



in Bimana, Proloscidia (where, however, the right lung sends off 

 a lobular process), and Cete. 



* Not in the Alliffatov orGaviaL 



