Taxonomy was the part of biology dealing with the definition and classification of organisms. One taxonomic rank was the genus. (TNG: "The Chase", VOY: "Tattoo", "Distant Origin") Examples of taxonomic nomenclature, which were usually rendered in Latin include "Felis catus" (cats) (TNG: "Schisms") and "Homo sapiens" (Humans) (TOS: "Mirror, Mirror", "The Empath", Star Trek VI: The Undiscovered Country)
Numerous taxonomic Earth animal names appeared on Spock's phylum search mode including: Myotis volans, Sebastes mustinus, Sciurus griseus, Ciona intestinal, Ovis dalli, Crisia occidental, Chama arcana, Dasypus novem, Vulpes velox, Martes pennanti, Plethodon dunni, Alopex lagopus, Cancer productus, Podiceps auritus, Sebastes mustinus, Coleonyx brevis, Cervus elaphus, Tursiops tancts, Orcinus orca, Beardius baerdi, Ziphius cavitro, Physeter macro, Megaptera novaeangliae. (Star Trek IV: The Voyage Home)
Data's poem Ode to Spot included the line "Felis catus is your taxonomic nomenclature". When a malfunction of USS Enterprise-D computer in 2369 caused the overwriting of several ship files with Data's personal files, the line about the taxonomic name of cats appeared on a PADD instead of the text of Something for Breakfast. (TNG: "Schisms", "A Fistful of Datas")