As quoted from Brophys' Book on Marlin:
"In 1922 when the newly formed Marlin Firearms Corporation was formed, under the leadership of John Moran, a bull's-eye design became the new Marlin trademark. It not only was used on printed matter but also was inlaid into the bottom surface of the buttstock of each firearm. A statement about the bull's eye by Marlin Firearms Company was as follows:
Every single Marlin bears a "birthmark" which instantly identifies it. Customers in your store have but to glance at the butt of the gun to know it is a Marlin. The bulls'-eye-symbol of accuracy- is the most fitting kind of trademark for Marlin, make and breaker of World's target records. Inlaid in black and white on the butt of every Marlin arm, it makes not only a complete identification, but a beautiful accent of decoration.
You will realize what an enormous helpful thing this is, saving you time and paving the way for a sale. Your years of selling experience will tell you that merchandise which can be immediately identified has selling value almost beyond price.
The bull's-eye trademark is still in use today, and except for a year or two during the Depression years of the 1930s, the bull's-eye has been installed in the stock of every Marlin model of rifle and shotgun. It has not been used on "brand name" or Marlins' Glenfield line of guns.
The location of the bull's-eye in the stock is usually 4 to 4 1/2 inches forward of the toe of the stock.
Frequently, the bull's-eye is incorrectly thought to be the location where a lower sling swivel should be installed (lower sling swivels are usually about 3 inches from the toe of the stocks)
That about wraps it up, hope it helps. Understand that the above is from a book published in I think 1989, things have changed some since then. Mr fixit.