The value of a herbarium is much enhanced by the possession of 'types', that is, the original specimens on which the study of a species was founded. Thus the herbarium at the British Museum, which is especially rich in the earlier collections made in the eighteenth and early nineteenth centuries, contains the types of many species founded by the earlier workers in botany. It is also rich in types of Australian plants from the collections of Sir Joseph Banks and Robert Brown, and contains in addition many valuable modern collections.