A review of the extensive collection of Sminthopsis in the Australian Museum in 1929, revealed a wide range of variation in. the structure of the pads of both manus and pes in specimens hitherto allocated to the fat-tailed species, Sm. crassicaudatus. These pads become so shrunken and distorted by drying that spirit series are essential, and there is no doubt that lack of such material has resulted in far too great a range being accorded to individual species in the past.
In his remarkable Catalogue of 1888 Thomas gave the range of crassicaudatus as the "Whole of Australia (not yet recorded from the extreme north)", and included Ramsay's Antechinus froggatti from Derby, N.W. Australia, in the synonymy of that species. Examination of Ramsay's holotype, however, provides characters warranting the distinction of the Derby form, and it is proposed later on to deal with several races occurring in eastern Australia, as indicated by the Museum material.