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CLASS III. 



Corticiferous Polypidoms, composed of two substances, 

 one exterior and enveloping, called rind, or iticrustation, 

 the other named axe, placed at the centre, and support- 

 ing the first. 



GENERA 



BELONGING TO THE FIRST ORDER OF THE THIRD CLASS. 



Polypi none, or not perceptible. 



Ephydatia. Fresh-water Polypidom, of a spongy 

 nature ; colour green ; and in long masses, which are 

 lobed or bundled together. 



Spongia. Polypidom of a porous mass, lobed, 

 ramified, turbinated or tubulous ; formed of horny 

 or leathery fibres, flexible, interwoven, or glutinated 

 together, and surrounded or enveloped, in a living 

 state, with a gelatinous, irritable, and very fugitive 

 substance. 



GENERA 



BELONGING TO THE SECOND ORDER OF THE THIRD CLASS. 



The Polypidoms of this order are usually tree- 

 formed and inarticulated ; the interior consisting of 

 an axe, in general horny and flexible, sometimes 

 sufficiently hard to receive a fine polish, at others 



