Through the kindness of Mr. A. N. Burns, to whom I wish to express my appreciation, I had the opportunity of examining the Gyrinidae of the National Museum of Victoria. The study of this interesting material led to the discovery of a remarkable new species of the genus Macrogyrus from Central Australia, which will be described. Moreover, I am enabled to give a detailed description of the nearly legendary Macrogyrus venator Boisd., which was represented in the collection by several specimens from Wessel Island, proving its affinity with the Australian fauna and removing the doubts alleged heretofore. Besides new records concerning already known species, I am adding remarks supplementary to my paper on Australian Gyrinidae published in 1949 (Rec. Aust. Mus. 22 (2):171–199).