MONOTREMATA

Monotremata, order Monotremata

(noun) coextensive with the subclass Prototheria

Source: WordNet® 3.1

Mon`o*trem"a*ta, n. pl. Etym: [NL., fr. Gr. (Zoöl.)

Definition: A subclass of Mammalia, having a cloaca in which the ducts of the urinary, genital, and alimentary systems terminate, as in birds. The female lays eggs like a bird. See Duck mole, under Duck, and Echidna.

Source: Webster’s Unabridged Dictionary 1913 Edition