This bookplate is a black and white engraving depicting the arms of William Gilliland, Sr., the pioneer patriot, explorer and settler of New York's Champlain Valley. A description of the Gilliland Arms may be found in this reference:
Bessboro: a History of Westport, Essex Co., N.Y.
By Caroline Halstead Royce
"The first owner of land in Westport, William Gilliland, who surveyed the boundaries of Bessboro in 1764, bore arms, --'azure, a lion rampant argent,' that is, a silver lion standing upright on a shield of blue. The crest is a right hand with a mailed wrist, clenching the handle of a dagger, the helmet above the shield is that of an esquire, and the motto is 'Dieu et mon pais' ('God and my peace' in old French). These arms are still used on the bookplate of the Gilliland family,
"Next we may hang the arms of the Irish Bessboro, an earldom of the Ponsonby family in the south of Kilkenny, which Gilliland doubtless had in mind when he named this patent, although we know of no real connection between him and the Ponsonby estate...."
The bookplate is among the collection of Lew Jaffe, who kindly permitted this photo to be displayed in the Gilliland Trails library collection. The only difference I noticed between the bookplate and the description in Royce's book is that the hand above the shield is clenching not a dagger but a sword.
– Kate Maynard