HART'S-TONGUE (Phyllitis), the name given to a genus of ferns, formerly known as Scolopendrium, meaning "like a centi pede," from the numerous lines of fructification on the leaves. P. Scolopendrium (S. vulgare) is common in Europe, including Great Britain, and extends into Asia and North America, but is very rare in the latter continent, occurring only locally in central New York, Tennessee, Ontario and New Brunswick. The thick, leath ery, glossy fronds reach a length of 18 in. There are ten spe cies of Phyllitis, mainly tropical and subtropical. (See FERN ; PTERIDOPHYTA.