576 



ANATOMY OF VERTEBRATES. 



the cartilaginous rings, fifteen in number, are broad, entire, and 

 slightly overlap each other : the bronchial annuli are bony, and 

 are continued ot that texture through a great part of the lungs. 

 The right lung is divided into three lobes, of which the smallest, 

 448 ib. n, fills the interspace 



between the heart and dia- 

 phragm: the left lung, o, 

 is undivided. 



In the Echidna the tra- 

 chea is narrower : there 

 are twenty- two tracheal 

 hoops, which are disunited 

 behind ; very firm cartila- 

 ginous annuli are con- 

 tinued along the larger 

 branches of the bronchus 

 for some way into the 

 lung. 



In the condition and 

 structure of the respira- 

 tory organs all the marsu- 

 pial species adhere to the 

 mammalian type ; the only 

 tendency to the Ovipara 

 is in the entireness of the 

 tracheal rings in certain 

 species. In the Phalan- 

 gista fuliginosa, where I 

 counted twenty-nine rings, 

 the first four-and-twenty 

 were entire; below these 

 they were divided posteri- 

 orly, the interspace grow- 

 ing wider to the twenty- 

 ninth ring. In the Da- 

 syurus macrurus the rings of the trachea are twenty-three in 

 number, and are incomplete or rather ununited behind. In the 

 Perameles the tracheal rings are divided posteriorly by a fissure. 

 The lungs in the Wombat consist of a single lobe on both the right 

 and left sides, with a small lobulus ' impar' extending from the right 

 lung to the interspace between the heart and diaphragm. In Ma- 

 cropus major the right lung has two notches on the anterior margin, 

 the left lung is undivided. In Macropus Parryi both lungs had 



Capillaries of the air-cells ; luug of Cow ; magn. cclxvii 



