||Che*lo"ni*a (k&esl;*lō"n&ibreve;*&adot;), n. pl. [NL., fr. Gr. chelw`nh a tortoise.] (Zoöl.) An order of reptiles, including the tortoises and turtles, peculiar in having a part of the vertebræ, ribs, and sternum united with the dermal plates so as to form a firm shell. The jaws are covered by a horny beak. See Reptilia; also, Illust. in Appendix.