20 



PRELIMINARY NOTE ON THE BREEDING OF ORNITHOBIIYNCHUS 



IN 1920. 



By Harry Burrell. 



Since Part I. of my paper, ''Field Notes on the Life History of Monotremes," 

 appeared in Part 8 of Vol. I. of this journal, I have spent another breeding sea- 

 son in the field. So much additional material, and so many new observations have 

 accrued, that I have felt it advisable to delay the publication of Part 2 until this 

 new matter can be incorporated in it. Meantime the material collected is of such 

 prime importance as to justify the present brief account of it. 



Professor Harrison, of the Sydney University, on learning that I proposed 

 to make another trip in 1920, impressed upon me the importance of properly pre- 

 serving any embryonic material obtained, and I have to thank him and his second 

 in command, Mr. E. A. Briggs, as well as Mr. W. Graham, the laboratory as- 

 sistant to the Department of Zoology, for sending me off adequately equipped 

 with fixing fluids and full instructions as to the methods of using them. The 

 same gentlemen also obtained for me from the Chief Secretary's Department a 

 permit to collect for the University embryological specimens of Ornithorhynchus, 

 which is, of course, totally protected. I also took with me a thermometer, which I 

 had carefully standardised before leaving Sydney, for the purpose of obtaining 

 the temperatures of the nesting burrows, and of the females captured in them. 



The locality chosen for my operations was the same as in 1919, namely, the 

 Manilla district. Last year, it will be remembered, I spent the month of October 

 in this district, during a period of record drought, and dug out six nests contain- 

 ing young, two with one, three with two, and one with three young, all of which 

 were in a fairly advanced condition. The youngest showed hair appearing be- 

 neath the skin, while the oldest were fully furred. 



In the spring of 1920 I was kept informed by Mr. J. Maclean, of Retreat 

 Station, Macdonald River, of the condition of the rivers, and of the numbers of 

 platypus observed. Tn July the three rivers, Manilla, Macdonald, and Namoi, 

 were all in flood, and ten feet above normal level. Falls of rain during the two 

 succeeding months maintained the rivers in a flood condition. 



Platypus were reported plentiful, and, as my objective was eggs, I estimated 

 what I considered the right time to go, and proceeded to Manilla in the middle 

 of September. The sequel proved that I had judged aright, as the following 

 tabular statement of results shows : — 



Sept. 20. — Nest with one egg. 



do. 20. — Female with two intra-uterine eggs. 



do. 22. — Nest with twin eggs. 



do. 27. — Nest with one young. 



do. 28. — Nest with twin eggs. 



do. 28. — Nest with one egg. 



do. 30. — Nest with twin young. 

 Oct. 2. — Nest with twin eggs. 



do. 2. — Nest with twin young.. 



do. 3. — Nest with triplet young. 



do. 4. — Nest with twin young. 



do. 6. — Nest with twin eggs. 



