Sciuropterus setosus, collected by Horner in the neighborhood of Padang (Sumatra) and described by Temminck in the »Fauna japonica”, seems to be such an extremely rare animal, that the type-specimen — an adult female — is the only individual hitherto observed by collectors and naturalists. Mr. Anderson is one of the few authors which have paid some interest to our little animal, but he has been not very successful in his remarks and observations. For, having studied in our Museum all our specimens before publishing his bulky work ¹), he came to the remarkable conclusion that Temminck’s setosus is a not fully grown specimen of Sciuropterus (Pteromys apud Anderson) pearsonii Gray, Trouessart (Catalogue des Rongeurs, 1881) blindly accepted Anderson’s view, but incorrectly gave the locality, as we find in Trouessart’s Catalogue »Birmanie supér., Sikkim, Darjiling”, instead of Sumatra”. Transiently I observe that Temminck’s »Fauna japonica” has been published in 1850, not in 1847, as Anderson and Trouessart quoted.