6 MAMMARY APPARATUS OF THE MAMMALIA 



Gl. mamm. 



Fig. 2. — Ornithorhynchus : Ventral View, showing 

 THE Mammary Glands. (After Klaatsch.) 



Gl. mamm.. Mammary glands ; d., cloaca. 



sink to a pouch, because here there is a 

 place of least resistance. But in the case of 

 Ornithorhynchus there is no such muscle- 



