Sentence:  Even in the mid seventeenth century a country gentleman might regard his <WSD>caul</WSD> as a treasure to be preserved with great care, and bequeathed to his descendants. 
Meaning of the word marked with <WSD> tags:  The amnion which encloses the foetus before birth, especially that part of it which sometimes shrouds a baby's head at birth (traditionally considered to be good luck). (from 16th c.)