My guess is the backing is hickory, and the main limb lam is yew. I've seen and owned a bunch of bows from this era, and never seen the extra lams in the middle, nor the metal arrow plate/wood shelf on yours. Along with the backset in the limbs, and the configuration of the grip material, this is a truly unique old bow!!(of course, you knew that!) Actually, the horn nocks look kind of familiar, but I can't put a finger on where that comes from.
Heck of a bow, Larry. Good find!