What is the X in X-mas?
1771, collective name for animals of a certain region or time, from Late Latin Fauna, a Roman fertility goddess, wife, sister, or daughter (or some combination thereof) of Faunus (see faun).
Popularized by Linnaeus, who adopted it as a companion word to flora and used it in the title of his 1746 catalogue of the animals of Sweden, "Fauna Suecica." First used in English by naturalist Gilbert White.
fauna fau·na (fô'nə)
n. pl. fau·nas or fau·nae (-nē')
Animals, especially the animals of a particular region or period, considered as a group.
Animals, especially the animals of a particular place and time.