Natural "contact lenses" in vertebrates.
D000717:Anatomy, Comparative; D000818:Animals; D001001:Anura / Q000033:anatomy & histology; D002645:Chickens / Q000033:anatomy & histology; D004372:Ducks / Q000033:anatomy & histology; D005123:Eye / Q000033:anatomy & histology*; D005399:Fishes / Q000033:anatomy & histology; D008116:Lizards / Q000033:anatomy & histology; D009541:Nictitating Membrane / Q000033:anatomy & histology*; D012754:Sharks / Q000033:anatomy & histology; D012911:Snakes / Q000033:anatomy & histology; D014714:Vertebrates / Q000033:anatomy & histology*