Talk:Plica semilunaris of conjunctiva

Contradictory information
I'm not an editor, in fact I'm thinking I'm not even writing this in the right place, but this article claims that there is only one species of primate with a functional nictitating membrane, but most lemurs have one. Can someone fix this? https://en.wikipedia.org/wiki/Lemur#Senses

It has contradictory information about the third eyelid. — Preceding unsigned comment added by Zsendukas (talk • contribs) 23:19, 29 April 2007 (UTC)

Vestigial organ?
How can it be a vestigial organ when it has a purpose (secreting rheum, to remove debris from the eye)? —Preceding unsigned comment added by Rmeden (talk • contribs) 14:46, 20 June 2009 (UTC)


 * Human vestigiality defines a vestigial trait as one that has lost "all or most" of its original function. This is certainly true of the plica semilunaris - it has lost much function, but not all. Hairy Dude (talk) 14:09, 11 May 2019 (UTC)

Not vestigial in everyone
The nictitating membrane is not a vestigial remnant in everyone. I know this because I have a functioning, but involuntary, nictitating membrane. Mine is white and opaque. I was told that this trait is common in Northern China and Mongolia, but I have never been able to confirm this. Does anybody know of a reference? (I am white and from european ancestry, not that it matters.) HairyWombat 21:48, 8 December 2011 (UTC)