In 1894, William Augustus Horn, a wealthy South Australian pastoralist and miner, organised an exploration of Central Australia. The Victorian government commissioned Walter Baldwin Spencer (1860-1929), Professor of Biology at the University of Melbourne, to participate as the expedition zoologist. Spencer not only joined the group on its arduous journey but also edited a major publication on its results. The Horn Expedition collected animals of all sorts for the museum, including numerous rarely encountered species. The collections were supplemented by material supplied by local landholders. Many of the species represented are now considered extinct or threatened, making the examples from the expedition a unique resource for research and education.
Several authors published their findings on the expedition's vertebrate collections in research journals and in the four volumes edited by Spencer. Under agreement, the expedition's specimens were dispersed across several institutions; 19 birds were sent to the British Museum (Natural History), but many mammals were deposited with Museum Victoria. Spencer and E.R. Waite examined the mammals obtained by the Horn Expedition. Spencer described five new taxa: the Fat-tailed False Antechinus, the Sandhill Dunnart, the Kowari, the Stripe-faced Dunnart (through individual variation in the species the Stripe-faced Dunnart received two names; these two animals are now correctly identified as being of the same taxon). Waite was especially interested in rodents, describing three new species: the Central Rock Rat, the Shark Bay Mouse and the Sandy Inland Mouse. The museum's specimen of the Spinifex Hopping Mouse was originally retained by Spencer at his university office and not received at the museum until two decades later. The species was not recognised as new until 1922. Today, the carnivorous Mulgara is considered to be vulnerable in its arid habitats. The museum's specimen is an adult male collected at Charlotte Waters, where the species was regarded as common in 1894.