CHAPTER II 



skeleton of urodela and anuka skin colour- changing 



mechanism- poison-glands spinal nerves respira- 

 tory organs suppression of lungs urino -genital 



organs fecundation nursing habits development 



and metamorphosis 



Skeleton of the Urodela 



The vertebral column. — The number of vertebrae is smallest in 

 the terrestrial, greatest in the entirely aquatic forms, and is excep- 

 tionally large in the eel-shaped Amphiuma. In the following 

 table the sacral vertebra is included in those of the trunk. , 



The vertebrae of the Urodela and those of the Apoda differ 

 from those of all the other Tetrapoda ^ by possessing no special 

 centra or bodies. That part which should correspond with the 

 centrum is formed either by the meeting and subsequent complete 

 co-ossification of the two chief dorsal and ventral pairs of arcualia 



' Credner's term for all Vertebrates higher than fishes. 



