
THE ADDER'S TONGUE. 335 
the exotic species, which gives rise to four sectional groups :— 
8 Euophioglossum, in which the fertile branch is solitary, and the 
sterile ovate or linear-oblong, represented by our two indigenous 
species ; $ Ophioderma, in which the fertile branch is solitary, and 
the sterile ribbon-like dichotomously branched or more rarely 
undivided, represented by the O. pendulum of the Eastern Archi- 
pelago ; $ Rhizoglossum, in which the sterile and fertile fronds are 
distinct, represented by the O. Bergianum of South Africa; and 
$ Cheiroglossum, in which several fertile spikes are developed from 
the margin of the hand-shaped sterile frond near its base, repre- 
sented by the O. palmatum of the West Indies. 
The genus is widely distributed, occurring in most parts of the 
globe. On account of the simple form of their fronds, the species 
present much similarity of aspect; but though comparatively few 
in number, they may be regarded as more numerous than appears 
to be admitted by some modern botanists. They are, however, as 
in other simple-fronded genera, really difficult to discriminate. 
The name is derived from the Greek ophis, ophios a serpent, and 
glossa a tongue, and hence the vernacular name of Adder's Tongue. 

SYNOPSIS OF THE SPECIES. 
1. 0. vulgatum: larger; barren branches of the fronds ovate-obtuse, or some- 
times narrower and more elongated ; fertile branch linear. 
2. O. lusitanicum : minute ; barren branches of the fronds linear or linear-lanceo- 
late, fleshy ; fertile branch linear oblong. 

