Early motorcycle seat.

I got an e-mail from a lady a couple weeks ago who said she had an antique bicycle seat. I finally got over to her shop today and ended up buying it. But as soon as i seen it i was skeptical it was off a bicycle due to the size. Its very early and heavy. the seat itself is 13" long by about 12 1/2" wide. So is it off a motorcycle or a bicycle? I added a pic of it on the seat thats on my Whizzer to show the size. Also any help on value.

Thanks for any help.
Robert