Erayga "Genus" waxa uu tilmaamayaa kala soocida taxonomic ee bayoloji oo ay kooxuhu isu geeyaan noocyada xidhiidh dhow la leh. Masaskan waxaa laga helaa Waqooyiga iyo Koonfurta Ameerika, waxayna caan ku yihiin rafaadka kala duwan ee dabadooda, kuwaas oo ay u isticmaalaan digniin digniin ah marka loo hanjabo.Haddaba, macnaha qaamuuska ee ereyga "Genus". Crotalus" waxaa loola jeedaa kala soocida taxonomic ee koox jilbisyo sun ah, oo loo yaqaan rattlesnakes, oo ka tirsan qoyska Viperidae.