This is the wikipedia entry for the "Mermaid Problem" as it appeared from Google cache on February 17, 2010. It was deleted from Wikipedia on February 25, 2010.
Mermaids at Play, 1886, by Arnold Böcklin
The Mermaid problem is an observation occasionally mentioned in literature, concerning the difficulty of having sexual intercourse with a mermaid. Although mermaids are commonly depicted as beautiful, variably nude, and enticing, a man attempting to have sex with one would be thwarted by the typical portrayal of the creature: a fish from the waist down, with no vagina. More generally, it can also be a joking reference to the unusual sexual interest many non-human characters seem to have with humans in fantasy or science fiction, and potential physical issues therein. A reverse mermaid, or a mermaid with the fish half on top and human legs is typically referred to as a "Merfish".
* 1 Mythical biology
* 2 Historical perspective
* 3 Examples
* 4 See also
* 5 References
If the mermaid were biologically a fish below the waist, theoretically they would reproduce as most fish do, by external fertilization, requiring a human male to deposit his seed underwater onto her eggs. (The confusion is further compounded by the fact that mermaids are usually depicted with a navel and breasts, which would suggest placental vivipary rather than ovipary.) However, this situation is sometimes rectified by portraying mermaids as having genitalia more similar to dolphins than fish. Since most mermaid sightings observe that the mermaid has a human upper body, complete with breasts, and a navel, we must therefore assume that the mermaid is in fact a mammal. The "fish" part below the navel must then be more akin to that of a dolphin, with the sexual organs being similar to that of a dolphin. The female dolphin has one slit in its lower belly, which contains both the anus and the vagina. Hence, making mermaid-human sex (as depicted in many myths, legends, and stories,) perfectly biologically possible. Another theory is that mermaids have the ability to change into human form, e.g. the fishtail splitting into two legs when it dries, and again turning into fishtail when the legs touch with water. A prominent example of this is the Touchstone Pictures film Splash where the Mermaid character Madison, portrayed by Daryl Hannah, transforms into human form and sustains a romantic and sexual relationship with Allen Bauer, portrayed by Tom Hanks, while retaining many of her undersea habits and mannerisms. A French idiom, finir en queue de poisson (to end with the tail of a fish), makes reference to this difficulty; it refers to a promising start that ends in disappointment. It originates from a line in Horace's Ars Poetica: Desinit in piscem mulier formosa superne (the beautiful woman ends in a fish's tail).
Interestingly this was not always an issue. In the past it was not uncommon for a mermaid (actually a medieval siren or melusine) to be portrayed as having a split tail, with a vagina located (or merely implied to be) between the two parts. H. P. Lovecraft's short story "Dagon" and the logo of the American coffee chain Starbucks are examples of this. In the original version of the logo the mermaid is shown spreading her tail apart up to her head. While this has been cropped out, and the drawing in general slightly reworked over the years, her tails are still visible around the edges.
In the Futurama episode "The Deep South", Fry befriends and romances a mermaid from the lost sunken city of Atlanta. He later has his hopes dashed after attempting sex with a very confused partner, who expected sex more typical of a fish. As he runs away from Atlanta he laments, "Why couldn't she have been the other kind of mermaid, with the fish part on top, and the lady part on the bottom?"
The other kind of mermaid.
In the Red Dwarf episode "Better than Life", the Cat solves the same problem while playing a virtual reality game when he dates a mermaid with exactly that physical description. When ship's mainframe Holly notes "Somehow I'd imagined she'd be a woman on the top and a fish on the bottom," the Cat replies "No, that's the stupid way around!" Coincidentally, Craig Charles (who plays the character David Lister on Red Dwarf) also plays the title role in the Channel 4 sitcom Captain Butler, who is enticed to wed a mermaid but reconsiders as he finds out he has to be transformed into a half-man-half-fish hybrid with the "fish half on top".
The poet/songwriter Shel Silverstein made this problem the centerpiece of his humorous song "The Mermaid", about a sailor who is warned against falling in love with a mermaid, which he proceeds to do. The lyrics read in part, "From her head to her waist she was my taste but the bottom part was a fish." The song ends with the sailor dejected after being dumped by his new mermaid love, but finding consolation when "her sister swam on by, and set my heart awhirl / For her upper part was an ugly old fish but the bottom part was girl!" The song is covered on the Great Big Sea album The Hard and the Easy. The album's cover features a "reverse mermaid" with an enticing pair of crossed legs in high heels, with the upper body of a fish. The back artwork shows a regular mermaid.
Another example of a reverse mermaid is a surrealist painting by René Magritte which depicts a mermaid with a fish torso and woman's legs which has washed up on shore.
The folk song "The End of the Tail", a parody response to the Meg Davis song "Captain Jack and the Mermaid", hinges on this issue of a mermaid's lack of traditional female parts.
In season 27, episode 1, of Saturday Night Live, a sailor (played by Will Ferrell) crash landed on an island and met a mermaid, played by host Reese Witherspoon. He wanted to know who her parents were and was confused about her being half woman half fish. The mermaid then introduced her father who sang about how he has "had sex with a lot of things" and about her own fish genitalia, grossing out the sailor. The father also addresses his view: "It's no crime to hump a fish".
In the Family Guy episode "Lois Kills Stewie," Lois Griffin is saved after being gunned down on a ship at sea and falling overboard by a merman whom Lois describes as "kind of the reverse of what you'd expect a merman to be," being that he had the upper body of a fish and the legs of a man, his loin covered with a seashell. He offers to make love to her, but she turns him down due to his awkward appearance; the merman "puts a huge hole in [her] logic" by saying that having a man's lower body is the only way he can have a penis.
The webcomic Penny Arcade also makes a joke on this subject when Gabe remembers his younger "Undersea adventures" or, rather, his attempts at having them. The comic closes with him asking Disney's Little Mermaid "Where the hell is your vagina?"
In a short story called "The Fisherman and his Soul" by Oscar Wilde a man falls in love with a mermaid and goes to live with her under the sea. After wisdom and wealth fail to entice him back to land, he returns to see the beautiful legs of a dancing girl.
A simple joke goes along the lines of a fisherman catching a mermaid, but deciding to let her go. His assistant asks "Why?" to which the fisherman replies, "How?"
P. C. Cast wrote of this particular problem in her novel "Goddess of the Sea" from her Goddess Summoning series. Within, the mermaid in question does have sex with a merman, though it is never fully explained.
In Piers Anthony's novel Mercycle, a race of merfolk who are the genetically modified descendants of normal humans appear. Although they appear to have a standard tail, the tail is actually divided in two in a structure closely based on human legs. In the standalone novel Mute, Anthony described a mermaid whose tail began at her knees. And In the Xanth series mermaids only appear as mermaids when they are in the water, turning into humans when they go on land.
In a short story by Francesca Lia Block titled "Mer", from her book Nymph: Nine Erotic Stories, the mermaid and the main character share a fulfilled sexual relationship through the use of oral sex, eliminating the necessity of a vagina.
The third and fourth installments of the adult film series Talk Dirty To Me feature mermaids who look to have sex with human men. In both films, the mermaids' tails automatically appear when the mermaids are in water, just like in the mainstream film Splash. When they are dry, however, the mermaids are able to change their tails to legs and back, at will.
In the mythos of contemporary poet Paul Shepard, the 'mermaid problem' is not regarded as a problem at all, but as the mermaids' essential significance. In his The Siren Idea, Shepard's antihero narrator claims that an unnamed rival "invented" mermaids. This is presented as an act of plagiarism, derivative of the narrator's previously formulated "Principal of Impenetrable Beauty, [...] proving the sublimity of unconsummatable [sic] lust." 
Alice Munro's story "Too Much Happiness"  includes a reference to a Russian mathematician attempting to solve the "mermaid problem" with mathematical theories.
In the episode "The Laughing Fish" of Batman: The Animated Series, there is a gag referring to this where The Joker seems to be flirting with Harley Quinn by asking her to "be [his] little mermaid." He then puts a giant fake fish head over her head, to which Harley responds, "You're really sick, you know that, boss?"
I've decided to post this whole thing as I think it's a shame that Wikipedia decided to delete it.