 Agassiz provides several potential solutions : the species of lobster could have a single genus " by the side of all the other classes with their orders , families , etc . " , or a family with one genus and one species , or a class with one order and one genus , etc . Agassiz concludes a single species is sufficient to derive the entirety of the hierarchy : at the time , this would have been " a distinct genus , a distinct family , a distinct class , a distinct branch . " The point of the sunfish is not observing characteristics that distinguish individuals , species and genus , but rather characteristics that are held in common higher up the taxonomic hierarchy . Scudder 's observation that finally satisfies Agassiz is that the sunfish has bilateral , paired organs ; a characteristic that Winsor notes is common to all vertebrates . 
