In*ter`ca*la"tion (?), n. [L.
intercalatio: cf. F. intercalation.]
1. (Chron.) The insertion of a day, or
other portion of time, in a calendar.
2. The insertion or introduction of anything
among others, as the insertion of a phrase, line, or verse in a
metrical composition; specif. (Geol.), the intrusion of a bed
or layer between other layers.
Intercalations of fresh-water species in some
localities.
Mantell.