Genus: Ymersaspis EL FEHRI, GROHGANZ, SANSOM, BENTON & KEATING, 2026
Etymology: Scottish Gaelic, saighead, "arrow" and Greek, aspis, "shield"the typical epithet of osteostrachian genera.

Species: agassizi (LANKESTER, 1870) EL FEHRI, GROHGANZ, SANSOM, BENTON & KEATING, 2026
= Eucephalaspis agassizi LANKESTER, 1870
= Cephalaspis agassizi (LANKESTER, 1870) STENSIO, 1932
Etymology:

Holotype: OUMNH PAL-C 31380

Locality: Cradley, Herefordshire, England, Southern United Kingdom.

Horizon: Lower Old Red Sandstone.

Biostratigraphy:

Age: Lochkovian Stage, Early Early Devonian Epoch, Early Devonian.

Material: Nearly complete but deformed hedshield.