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CLASS I.— ORDER III. 
Plant-like Polypidoms , tubular , simple or branched, 
never articulated ; of a horny or membranous substance 9 
but sometimes slightly covered with a calcareous layer 
neither cellular nor porous : Polypidoms situated at the 
extremity of the sterns, 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 
