100. =Foot joint= (_Podarthrum_). The junction of the tarsus below
with the foot.
101. =Podotheca= (_Podotheca_). The horny or skinny covering of
lower tibia, tarsus, and feet.
102. =Knee= (_Genu_). The junction of the thigh with the leg,
usually concealed by the skin.
103. =Heel joint= (_Suffrago_). The junction of the leg with the
tarsus.
103½. =Tarsus= (_Tarsus_). The third joint of the leg and next to
the tibia; covered generally with horn, sometimes with naked skin or
feathers, never with flesh; the toes are articulated to its lower
extremity. This joint corresponds to the ankle joint of the human
body.
104. =Instep=, or =Front of tarsus= (_Acrotarsium_). The anterior
face of the tarsus, usually covered by small plates, which in the
higher groups are united into one; sometimes covered by skin.