Of male animals

that have their testicles placed frontwards, some
have them inside, close to the belly, as the dolphin; some have them
outside, exposed to view, close to the lower extremity of the belly.
These animals resemble one another thus far in respect to this
organ; but they differ from one another in this fact, that some of
them have their testicles situated separately by themselves, while
others, which have the organ situated externally, have them
enveloped in what is termed the scrotum.