Molluscs,

such as the octopus, the sepia, and the calamary, have
sexual intercourse all in the same way; that is to say, they unite
at the mouth, by an interlacing of their tentacles. When, then, the
octopus rests its so-called head against the ground and spreads abroad
its tentacles, the other sex fits into the outspreading of these
tentacles, and the two sexes then bring their suckers into mutual
connexion.

Some assert that the male has a kind of penis in one of his
tentacles, the one in which are the largest suckers; and they
further assert that the organ is tendinous in character, growing
attached right up to the middle of the tentacle, and that the latter
enables it to enter the nostril or funnel of the female.