Webster 1913! I am shocked, appalled and dismayed! This is a most unhelpful and self referential definition.
Lucky for you (and the many many noders who, I'm sure, will be needing this write up for enriching their lives and linking their excellent nodes to) factgirl is here to bail you out.
All land vertebrates' limbs (including humans') are based on this original scheme: tassel-finned or fringe-finned beasts emerged from the water with a limb architecture of one bone from the shoulder or hip, two bones from the elbow or knee, and several bones from the wrist or ankle. The tassle/fringe pre-finger/toes are what make them members of the the Crossopterygii.