It perhaps will for ever remain an insolvable puzzle why Sir Raffles described under the name Mus sumatrensis a Mouse (after a drawing and a specimen) not from Sumatra, as the name should give reason to believe, but from Malacca, an animal after Major Farquhar not uncommon there and perhaps to be found in most parts of the Mahay peninsula. Sir Raffles’ paper has been read December 5, 1820, communicated by Sir Everard Home in the meeting of the Linnean Society of London, and it does not appear that one of the members has been struck by the remarkable perplexing contradiction! Mr. Temminck thinking it nonsense to bestow upon an animal from the Indian continent the name of an island where the animal is unknown, called it dekan instead of sumatrensis. The latter name however — being nonsense or not — is the first given and ought to be generally accepted. Temminck was quite right in separating the species from the genus Mus: title Nyctocleptes, he gave it the generic so that the correct writing of the Malacca-animal would have been Nyctocleptes sumatrensis (Raffles), if not Mr. Gray a couple of years previously had created the genus Rhizomys for the reception of a new species from China and that of Raffles’. The name for the latter stands therefore as Rhizomys sumatrensis (Raffles). In the course of later years there have been found on the Indian continent several other species of large Mice belonging to the genus Rhizomys; so it might have happened that in Sumatra too a distinct species, quite different from Raffles’ sumatrensis, had been procured — what a confusion would have been the indispensable and unevitable consequence!