Long antique lace lappet in one piece, probably for a collar, we think. This measures 42" long end to end, and nearly 3 1/2" at the widest point, near the ends.
We believe this is probably bobbin lace rather than needle lace, but couldn't tell you if is was made by hand or machine made, or where it was made. I don't know a lot about lace, I'm sorry!
I've tried to get you good close-ups, though most of my photos here aren't the best, I know. I'd guess that this is linen rather than cotton, probably not newer than the mid-1800s.
It is a deep even ivory in color, and does have a few spots which I've left just as found. All in all, condition is amazingly good, it's been very carefully stored for well over 100 years.