that is a nice old mitt, definitely a keeper with the hook and grommet back. Looks to be in good shape. if that is your first find, you did well. The Decker Safety mitt is shown in this illustration from an A.G. Spalding ad from the 1890's. The back view is at far right. The extra layer of leather and edge band on top of the finger stalls was invented by Harry Decker in 1889 for protection of catchers fingers.

here is the 1889 patent drawing.

The perimeter lacing feature you mention was another patent by Harry Decker in 1891 and was meant as an improvement in adjustment or adding of interior padding resulting from wear and tear. Below is a picture of a mitt with the perimeter lacing and the Decker style finger guard. There are other photos and info at
http://www.baseballglovecollector.com that is quite interesting.
