522 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



the marsupial pouch. The former are found in 

 all the Mammalia, but in the Monotremata they re- 

 main at a low or indifferent stage in so far as the ducts 

 do not emerge to a common orifice, but open separately, 



Fig. 214. Diagrams of the Arrangements of the Ducts of the Mam- 

 mary Glands in various Mammals. 



A, Adult echidna ; B, human eiuhryo; c, adult Homo; D, adult mouse; E, embryo 

 of Bos ; F, adult Eos. (After Klaatsch.) 



either on the surface of the integument (Ornitho- 

 rhynchus), or in a special mammary pouch (Echidna) 

 (Fig. 214; A). In all other mammals, " true " or 

 " false " teats are developed, the former being found 

 when, as in man, the ducts of the gland converge and 

 open on an uprising projection (Fig. 214; c), or a 



