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GENERA OF CLASS III. 
Mopsea. Tree-like, with pinnated branches ; rind 
thin and adherent, covered with very small but long 
bags, bent in towards the stem, dispersed or subver- 
ticillated. 
Isis. Tree-like Polypidom ; rind very thick, friable, 
not adhering to the axe, from which it is easily de- 
tached ; cells dispersed and superficial. 
Adeona. Stem articulated like the axes of this 
order, but surmounted with a fan-shaped expansion, 
which is irregularly sown with small cells on each of 
its surfaces, and pierced with round or oval apertures. 
