This certainly isn't "The Great" one - but the tune is easy enough to find:

Silkie

Lyrics: Elizabeth Scarborough
(With adaptations by Muriel Doris)
SUNG TO THE TUNE OF:
"Lucille"
© Harold Bynum and Roger Bowling


CHORUS:
You picked a fine time to leave me, you seal.
The babe that I bore you just makes my head reel.
He'll only eat kippers, has four lovely flippers,
Loves to dive down the well for his meal.
You picked a fine time to leave me, you seal.


Oh, you were a silkie, or that's what you told me,
Though I'd have sworn you were a man.
A right comely boy, oh, you gave me much joy, oh,
But I never did understand.
I'd have cause to regret once you got your feet wet,
For a silkie, as I've come to know,
On hitting the water can swim like an otter
And balance a ball on his nose

CHORUS

Though we parted friendly, I think you should send me
Some child support, that is my wish.
Since I moved to Ohio, It's so hard, you don't know,
Just to keep that poor kid in fish.
And if I should remarry, it must be to some faery
Of silkie descent, or at least
To some understanding and most undemanding
Boy in the employ of Greenpeace.

CHORUS


As printed in "The Folk Process," SING OUT, Vol 41 No 2, Aug/Sept/Oct 1996

John