propterus

from The Century Dictionary.

• noun A genus of ganoid fishes of the family Macrosemiidæ, characterized by an elongated deep body, rhomboidal or almost six-sided scales deeper than long, a long dorsal fin subdivided into a high anterior and lower posterior portion, massive pectoral and pelvic fins, and a short pointed snout. The vertebræ are ring-like. From the Upper Jurassic.