Noun
a protective fold of skin in the eyes of reptiles and birds and some mammals
Source: WordNetIn addition to the protection of the upper and lower eyelids, crocodiles have a nictitating membrane that can be drawn over the eye from the inner corner while the lids are open. Source: Internet
The EC is also responsible for the pre-processing (familiarity) of the input signals in the reflex nictitating membrane response of classical trace conditioning, the association of impulses from the eye and the ear occurs in the entorhinal cortex. Source: Internet
The nictitating membrane as it covers the eye of a masked lapwing Nervous system The nervous system is large relative to the bird's size. Source: Internet