AL'LANITE, n. A mineral named from Mr. Allan, of Edinburg, who first recognized it as a distinct species. It is massive, of a brownish black color, and conchoidal fracture. A siliceous oxyd of cerium.
ALLANTOIS'or ALLANTOID', n. [Gr. a sausage, and form.]
A thin membrane, situated between the chorion and amnios in quadrupeds, and forming one of the membranes which invest the fetus in those animals.
