Sentence:  The <WSD>iridal</WSD> dark-brown of her serious eyes had the enigmatic opacity of an Oriental hypnotist's look (in a magazine's back-page advertisement) and seemed to be placed higher that usual so that between its lower rim and the moist lower lid a cradle crescent of white remained when she stared straight at you. 
Meaning of the word marked with <WSD> tags:  Pertaining to the iris of the eye.