SPECIES OF MAMMALS OF THE PACIFIC AREA 13 



When not seeking food the animals are active making or alter- 

 ing the long earthen burrows which they mine in the banks of 

 streams. The building of the nest which will contain the eggs 

 and young takes place about twelve days after mating, in Oc- 

 tober. To prevent shrinkage the eggs must be kept in a satu- 

 rated atmosphere. Quantities of leaves and grass, soaked in the 

 water, are gathered together, then wadded into tight packets 

 beneath the tail, and so are carried to an enlarged nest cham- 

 ber at the end of one of the tunnels. A series of earthen plugs 

 is maintained between the nest chamber and the several outlets. 

 They are believed to keep the atmosphere of the chamber moist 

 by checking air movements. Nest building is a strictly "busi- 

 ness" affair. When working at it the mother practically stops 

 feeding; she completes nest construction with the water-soaked 

 leaves in some eighteen hours. The first egg is apparently laid 

 within a day or two, the developmental period of the egg within 

 the mother's body having lasted about fifteen days. 



Incubation of the eggs requires some nine to ten days more. 

 During that time the mother platypus remains in her burrow 

 for periods of several days at a time. She eats little or nothing 

 and emerges merely to defecate. After the hatching of the eggs 

 the mother reverses her time-table; she again spends many 

 hours in the water feeding ravenously, and between times retires 

 to the burrow to feed the babies. For the first few days after 

 the eggs have hatched the mother seems to secrete no milk. 

 During that time she scratches the mammary area of her body 

 a great deal, which activity possibly helps to induce her milk 

 to flow. She does not wean her young until they are about four 

 months old and nearly as large as herself. At approximately 

 that time the mother develops a fine new coat of glossy fur. 



The baby platypus is a singularly helpless creature, quite as 

 helpless as a human baby. It remains unable to crawl until it 

 has grown almost as large as its parent, the only movements of 

 its limbs being feeble scratching efforts. It is nursed by the 

 mother until it is almost fully grown and has attained the weight 



