(syn. Passerculus Ϯ Baird's Sparrow P. bairdii) Gr. κεντρον kentron spur; ονυξ onux, ονυχος onukhos claw; "CENTRONYX, Baird. ... Hind toe very large; the claw rather longer than its digit, and in its elongation resembling Plectrophanes, but more curved; the digit and claw together rather longer than the middle toe and claw" (Baird 1858). Var. Centhronyx.