The number of mammalian type specimens in the ZMA is incredibly modest when one realizes that this institution was firmly established as a scientific taxonomical collection during the last quarter of the 19th and the first decades of the 20th century, in a country governing and studying one of the richest mammal regions in the world, i.e. the Dutch East Indies (present-day Indonesia). Indeed, this modest number of mammal types is not due to a lack of collecting and acquisitional efforts, but largely to two exceptional conditions prevailing in the first half of the 20th century.
Firstly, professor Dr Max W.C. Weber, director of the ZMA from 1898 to 1922, and his successor Dr L.F. de Beaufort, ZMA director from 1922 to 1949, exchanged many unidentified mammals newly acquired from the Dutch East Indies for fish specimens with the British Museum (Natural History) in London. There, Mr. Oldfield Thomas described the new species among them and, as can be expected with exchanges, only seldom sent a specimen back. Secondly, although sometimes Weber and De Beaufort themselves undertook taxonomical and biogeographical work on mammals (e.g. Weber, 1890-1891; De Beaufort, 1911), prior to 1945 there has never been a taxonomist on the ZMA staff who was explicitly responsible for the maintenance and study of the mammal collections. This lack of a curator of mammals is one of the underlying causes enabling the liberal use of mammals as material for exchange, and the ensuing serious impoverishment of the ZMA mammal collection.