Ischiopagus twins. Lower abdominal aras are fused and extremities consequently displaced laterally. Only one pelvis is present, associated with single normal external genitalia, the latter located between right leg of left twin and left leg of right twin. the legs are normal except for clubfoot. Opposite legs are fused into a single composite limb. Viscera of one was in situs inversus position. Aortas were fused. The heart of one twin was hypoplastic and circulation through that twin was in reverse direction through arteries and veins.