There were either twelve sexes or none.
It's a sentence I still remember, from a book or a short story, and I'm guessing it was published before the turn of the century (i.e. 1900's). The main character is explaining to the reader what he knows so far about a species he is observing and I believe is even living amongst.
That's all I've got. I know it's thin, but I think it is so distinctive, and I have a hunch what I was reading was probably so well known, that someone will likely recognize it quickly.