well, the human vagina is most certainly not an inverted penis- the vagina, while not sexually aroused, is collapsed, forming an "X", if you were to take a cross section. When sexually aroused, however, the vagina engorges w/ blood (just like the penis) and becomes mor dougnut-shaped (in cross-section)
The vaginal canal is internally angled to the same degree that the penis is angled away from the male's torso, so the angles match nicley. However, the shape of the uterin/vaganal junction does not resemble the head of a penis, so I'd say he's a bit off (without haing seen any of this drawings)
it is currently thought that the head of the penis is designed to pull out the sperm of a rival male during copulation, freeing up the area for your sprem (your as in the guy curently mating) The foreskin and the riged head work well for pulling liquid out, and leaving it on the outside of the vagina.
