146 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. 



