</a> Courtesy Smithsonian Institution National Numismatic Collection. Rare Currency at The Smithsonian The previous coin's older brother the 1849, Gold Rush era double eagle gold coin is valued by collectors the world over. It was the United States of America's first $20 denominational gold coin. Courtesy Smithsonian Institution National Numismatic Collection.
subspecies - (biology) a taxonomic group that is a division of a species; usually arises as a consequence of geographical isolation within a species. race. biological science, biology - the science that studies living organisms. taxon, taxonomic category, taxonomic group - animal or plant group having natural relations.
In biology, a species (abbreviated sp. , with the plural form species abbreviated spp. ) is one of the basic units of biological classification and a taxonomic rank. usable definition of the word species and reliable methods of identifying particular species are essential for stating and testing biological theories and for measuring biodiversity, though other taxonomic levels such as families may be considered in broad-scale studies.