Many thanks for these important gretian revivals, Alan! In her chapter on UK introductions of 1838–1848, Nicolette Gray¹ remarks that “the Grecian and the Roundedare both founded on the simple idea of taking the corner off the letter.”
As you have so astutely observed, US wood-type designers further developed this concept starting in 1846.²
¹Gray, N. (1938): XIXth Century Ornamented Types and Title Pages, page 42. Faber and Faber Limited, London.
²Kelly, R.R. (1977): American Wood Type, 1828–1900|Notes on the Evolution of Decorated and Large Types, pages 272–277. Litton Educational Publishing, Inc./Van Nostrand Reinhold Company (New York 1969). Reprinted by DaCapo Press, Inc. (New York 1977).