most species of marsupial (metatherian) and placental (eutherian) mammals have evolved extra-gonadal testes, although a limited number of these mammals remain testicond or exhibit differing degrees of testicular descent. as a result of the epididymis being attached to the testis, and the cauda epididymis extending below the lower extremity of the testis (figure 1c), it was proposed that the epididymis was the prime mover in the evolution of testicular decent, whereby the cauda epididymis preceded the testis into a scrotal location.