Gardner & Murdock, Green St., Boston (1825-1841) were successful makers of unusual planes. Most that I have seen are either of exotic woods, unusual forms or both.
This is an ebony, possibly Gaboon ebony, single iron block plane. The blade is set at 40 degrees, a slightly lower angle than usual for such a plane. Not quite a mitre plane but not quite a smooth plane.
The angle and the single iron, along with the ebony, fits the bill for the product Gardner & Murdock produced. Although I have no proof of this, I have always suspected that they made planes to order, either for their own customers or as a sub-contractor to other Boston area planemakers.
9 inches long, 1 1/8" wide, 1 5/8" iron set at 40 degrees. The mouth is very tight at 3/8", as befits such a plane. The breast measures 7/8" in height. The sides are straight, thus I feel safe naming this as a strike block plane.