G. PLEXAURA. 213 



pedicelled and urceolated at the summits of the 

 branches. 

 Norway. 



SCARLET. 



52. Gorgon I A coccinia. Branching ; branches 

 short, dispersed, and formed like Cladonias (some 

 exotic lichens) ; axe horny ; rind scarlet ; height from 

 three to five centimetres. 



Australasia. 



RED. 



53. Gorgon I A coralloides. Upright, and almost 

 dichotomous ; polypi projecting, and starry ; rind 

 red. 



Mediterranean. 



PLEXAURA. 



Tree-formed Polypidom, branching, and fre- 

 quently dichotomous; branches cylindrical and stiff; 

 axe slightly compressed ; rind in a state of desiccation 

 corky or earthy, very thick, effervescing but slightly 

 with acids, covered with numerous large and scat- 

 tered cells, unequal in size, and which never project. 



These Polypidoms differ from the two succeeding 

 genera by the form of the polypean opening, always 

 projecting in the Euniceas and Primnoas, but never 

 in the Plexauras. It cannot be confounded with the 



