The collection of Bats hereafter described has been presented to the Leyden Museum by our well known correspondent Dr. C. G. Young from Berbice, New Amsterdam, British Guyana. This collection tells us that, although our knowledge about the Bats may have increased during the latest years, much remains to be done before we can pretend to know exactly these most interesting creatures: especially the study of the South-American Bats is very difficult by lack of sufficient material. Therefore every addition may be called welcome.