LIFE HISTORY OP JIOXOTREilKS, 



235 



have at times found what 1 consider to be litter here and there in the subway, but 

 never actual nests. It would apparently be a simple matter for these animals to 

 scratch out an old nest, and replace it with new material, but this is evidently 

 not done. The exception referred to contained no less than four nests in different 

 positions (Fig. 3), three of which were in various stages of dilapidation, while 

 the fourth, though scanty in material, contained twins. Mr. Hoy examined 

 these four nests with me. and agreed that they bore the appearance of having 

 been built at different periods, probably at yearly intervals. The bank in which 

 this burrow was placed was unusually faulty for the purpose, having a sandy sub- 

 soil. It was on a beautiful stretch of water about three miles below the New 

 England water-falls, where the river is actually bridged in places by rocks, so 

 that when the water is at a low level, as in periods of drought, the river becomes 



Fio.'4. — A typical platypus haunt on the Manilla River at Manilla. H. Burrell, Photo. 



a chain of ponds which prevent the platypus from travelling far. Possibly, 

 therefore; the animal or animals which successively inhabited the four nests had 

 become river-locked, so to speak, and were compelled to make shift in the only 

 available faulty quarters. We dug out three other unoccupied burrows in the 

 same bank, each of which had evidently been abandoned on account of the surface 

 sand collapsing while the nesting chamber was being excavated. The platypu". 

 was perhaps compelled to shift along the bank until it chanced to find the old 

 burrow in the only part which could be used for the purpose, and it made itself 

 content by burrowing on past the vacant nests. Though I have found adult males 

 in those temporary burrows which are used for resting purposes only, I have 

 never observed one in any of the breeding-burrows I have examined; the female 

 has been their only adult inhabitant, while even she is not always at home with 



