96 



CLASS I.— ORDER 111. 



Plant-like Poli/pidoms, tubular, simple or branched, 

 never articulated ; of a horny or membranous substance^ 

 but sometimes slightly covered with a calcareous layer 

 neither cellular nor porous : Polypidoms situated at the 

 extremity of the stems, of their branches and their divisions. 



GENERA AND SPECIES. 



TIBIANA. 



Plant-like, and fistular; branches flexuous or in 

 zig-zag, with polypean openings at the sides, alter- 

 nate, and thinly scattered. 



The Tibianas are formed of numerous tubes, agglu- 

 tinated or fastened together without being anasto- 

 mosed. Their height varies according to the species or 

 individual ; the tubes separate, spread out, and assume 

 the form of branches, that are simple or very slightly 

 ramified, generally flexuous or in zig-zag : the open- 

 ings from whence come the Polypi are placed in a 

 prolongation of the tube, and at the extremity of each 

 bend produced by its flexuosity : sometimes these 

 openings are wholly directed to the base of the Po- 

 lypidom, usually they are vertical ; the tubes of the 



