PLACENTA IN PERAMBLES 125 



intra-uterine nutritional arrangements. Both genera are 

 absolutely on the verge of extinction. The intra-uterine 

 development of Thylacinus will probably never be known, 

 and it is extremely unlikely that detailed investigation will 

 be possible in the case of 8 a r c o p h i 1 u s . 



Under these circumstances it is a pleasure to acknowledge 

 gratefully any help extended towards an investigation of the 

 ontogenetic and phylogenetic relationships of this fast dis- 

 appearing fauna. 



First, in this way, I inust express my most grateful thanks 

 to the Trustees of the John Ralston Bequest and particularly 

 to their chairman, Dr. Ij. (t. Thompson, these gentlemen having 

 placed at the disposal of the University of Tasmania a sum of 

 money to be used chiefly in marsupial investigation. It is 

 mainly by their financial aid and unswerving support that 

 the important collection of embryological material in the 

 University of Tasmania has been brought together. 



Secondly, I am indebted to the Committee of the British 

 Association for the Advancement of Science, who, at their 

 Australasian meeting in 1914, placed at my disposal a grant 

 with the object of procuring material for the study of the brain 

 and embryology of marsupials. 



The preliminary portion of the examination of the material 

 of the present paper was carried on in my own laboratory, but 

 lack of facilities for consulting almost all the literature, and 

 other disadvantages of isolation in Tasmania, led me to consult 

 my old friend Professor 8. J. Johnstone as to the possibility 

 of accommodation in one of the laboratories of the University 

 of Sydney. 



This was arranged and the work was carried on under these 

 altered conditions. 



Still more recently, by the courtesy of Professors Hill and 

 Watson, I have been acconnnodated at l^niversity College, 

 London. I am indebted to the Senate of the University of 

 Sydney and to the Research Committee of that University 

 for a grant from the McCaughey Bequest to defray the cost 

 of the plates illustrating this paper. 



