palæaspis

Century Dictionary and Cyclopedia

1. n. A genus of ostracoderm fishes of the order Heterostraci, with the head covered by a simple, triangular, dorsal shield from 3–5 inches long, notched at the orbits and without posterior spine, and by a quadrate ventral shield. One species is from the Salina group of the Silurian in Perry county, Pennsylvania, the other from the Old Red Sandstone of the Scottish Devonian.