660 



MAMMALIA 



[CH. 



Prototheria, in Crocodiles and in Urodela. The young are quite 

 incapable of feeding themselves, but each becomes attached to the 

 opening of one of the ducts of the milk-gland, and the area of 

 attachment becomes drawn out into a teat, and therefore the 



FIG. 329. Petrogale xanthopw. The Rock Wallaby with young in pouch. 

 After Vogt and Specht. 



mother by compressing the muscles of the belly squeezes the milk- 

 gland and forces milk down their throats. In order to allow the 

 young one to breathe at the same time, the back of the soft 

 palate is wrapped round the upper end of the windpipe, which 



