Akademik

extinct small freshwater jawless fish usually having a heterocercal tail and an armored head; of the Silurian and Devonian

/euh nas"pid/, n. Paleontol.

any member of an extinct order, Anaspida, of small, freshwater jawless fishes of the Silurian and Devonian periods, characterized by a single nostril, narrow rows of scales, and, usually, an armor-plated head.

[ < NL Anaspida name of the order, equiv. to an- AN-³ + Gk aspid- (s. of aspís shield) + -a neut. pl. n. ending]