IN MALE MONOTREJIATA 7 



free area. Only in the immediate region 

 of the mammary glands are there two narrow 

 slits through which the gland-ducts pass. 



How under these primitive conditions the 

 young feed themselves has not yet been 

 accurately observed. Even the secretion of the 

 mammary glands has not yet been analyzed, 

 so that we do not know its relation to the 

 milk of the higher Mammalia. 



It is of great interest that the male Echidna 

 as well as the male Ornithorhynchus have 

 their mammary glands just as strongly 

 develojjed as the female, and that the appear- 

 ance of the panniculus carnosus in both sexes 

 is identical. But in the male Echidna the 

 incubatorium is never found, for physio- 

 logical reasons, because pregnancy does not 

 occur. As regards this development of the 

 mammary glands in the male, it would be 

 very desirable to know how they behave 

 during the suckling-time of the young. It 

 is very much to be regretted that nothing 

 is known about this as about so many other 

 details of the life-history of these animals. 



We are now approaching our particular task 

 of examining how the Mouotremes came into 



