Before the beginning of this year the only records of the occurrence of fossil marsupials in Western Australia consisted of the account of the discovery of Diprotodon bones in the Kimberley district by Mr. E. T. Hardman, the Government Geologist, in 1882, and the finding of a lower jaw of this animal in 1895 in a gully near Lake Darlot in the Eastern Goldfields by Mr. Arthur, who presented it to this Institution. This jaw was so much weathered that it was valueless except for the fact of its establishing the existence of that marsupial so far inland. The Museum Committee sent an expedition to Lake Darlot in 1898, and in 1908 the Hon. Dr. Hackett sent out at his own cost Mr. Young, who was with Mr. Arthur when he found the jaw in 1895. Both these parties were unsuccessful.