"...you know. it's a pity all Molly knows about mermaids involves swimming, singing, underwater exploring" Jane started as she and Carl got seated within the Clamshell. "those other stories i'm thinking your thinking of are inappropriate for those under 18 dear" Carl assured.
"well... it's just... with Molly asleep, her being 11 now and still a lonely child... and how personally though I rather Molly not know. such stories are my favourite porn" Jane seductively suggested while fingering Carl where his cock was hidden within his own tail before getting more blunt "ever dreamed of doing the dirty with a mermaid".
at first Carl was hesitant but the more Jane toyed the more pressure he felt and the thinner his resistance to the idea got. still Jane had a point, even after Molly was born they never stopped having sex at home but nothing ever resulted and at this point both had accepted that maybe they had reached their childbirth limit. but as the pressure eventually caused his cock to burst out big from it's hidden merman pocket Carl's resistance shattered as he embraced his willing wife, his cock going deep into her waiting mermaid vigina and the clamshell closed up as they let the passion overtake them.
"mmmm... you did not answer my question" Jane reminded Carl after a brief lip-lock. "only times I ever dreamt of mermaids you were one... most beloved and beautiful of all" Carl answered as the pair twisted their tails together while Jane's vigina clamped down tight to keep Carl's cock within her has long as desired.
the experience was new, wonderful and invigorating all in one with Jane enjoying it as Carl removed her seashell bra and let it float aside before he buried his head into her breasts. Jane joyfully followed by moaning in pleasure and sucking both Carl's neck and shoulders.
before they knew it the couple was rolling about in pleasure while switching between various position of kissing and enticing more pleasure out of each other and time seemingly stopping to have meaning. not that the intertwined tails, strong cock knot or tight vigina clamp did anything to remind the couple of this. right now all they cared about was taking advantage of this limited opportunity.
eventually however the climax arrived as Carl then Jane felt it as Carl started unloading all his built up cum into Jane, seemingly gallons upon gallons of it while Jane embarrassed joyfully and willingly the affection it showed Carl still had for her, more even as she could not remember the last time this much was resulted. still the pressure was more then the physical bonds could manage so soon the tails untwisted before Carl started shooting out of Jane as both his cock unknotted and her vigina unleashed it's grip, yet the semen tgat was still coming was now being sucked into Jane through her vigina.
but just before either could question this the orgasms hit them like Tsunamis, so pleasurable it blocked out all worries and so powerful the vibrations unleashed a shockwave powerful enough to blow the clamshell back open.
"now that...*gasp* was instance" Carl announced in gasps as his body finally relaxed while he and Jane just looked over to Molly's still closed clamshell. "I'm surprised Molly is still asleep through that" Jane returned in wonder. "*yawn* best not to wake her then" Carl suggested. "maybe this birthday holiday will be better then I assumed" Jane agreed as she and Carl finally went to sleep: