Bifurcated nose pads are specialty nose pads, meaning they really fit very few eyeglass frames. These nose pads are hard plastic nose pads with a metal insert or base that is a straight post with a V cut on the end of the post. As you can see the post is a straight rectangular piece. Although this looks very solid, the end is cut to allow the metal to be split or opened more. Meaning flattened after the post is inserted through the small opening in the nose pad arm.
One of the last remaining, the bifurcated nose pads are still around much due to the fact that the split pin and square pin nose pads took the popularity for fitting antique eyeglass frames.
Below you can see the lineup of the three special mount nose pads. the bifurcated (located on left) followed by the square pin nose pad (middle), and last, but not least, the split pin nose pad(right).