n. [ From T. Allan, who first distinguished it as a species. ] (min.) A silicate containing a large amount of cerium. It is usually black in color, opaque, and is related to epidote in form and composition. [ 1913 Webster ]

a. [ Cf. F. allantoïque. ] Pertaining to, or contained in, the allantois. [ 1913 Webster ]

Allantoic acid. (Chem.) See Allantoin. [ 1913 Webster ]

{ ‖ } n.. (Anat.) A membranous appendage of the embryos of mammals, birds, and reptiles, -- in mammals serving to connect the fetus with the parent; the urinary vesicle. [ 1913 Webster ]

{ } a. [ Gr. &unr_; shaped like a sausage; &unr_; sausage + e'i^dos form. ] (Anat.) Of or pertaining to the allantois. [ 1913 Webster ]

‖n. pl. [ NL. ] (Zool.) The division of Vertebrata in which the embryo develops an allantois. It includes reptiles, birds, and mammals. [ 1913 Webster ]

n. (Chem.) A crystalline, transparent, colorless substance found in the allantoic liquid of the fetal calf; -- formerly called allantoic acid and amniotic acid. [ 1913 Webster ]