Sentence:  Some months ago casts came to me from a friend in England, one showing six incisors in the deciduous <WSD>mandibulous</WSD> dentition of a child of about six years of age, and the other showing six incisors in the permanent dentition of the same patient at, I think, eighteen or twenty years of age. 
Meaning of the word marked with <WSD> tags:  Pertaining to the mandible.