VI! 
it comprehends the Flustreas, Cellarias, See. The se- 
cond Order includes all those with coalescent or 
united cells, formerly all styled Sertularia. The Tu- 
bular i a forms the third Order, their cells being tubular 
and horny, simple or branching, with one or many 
openings. 
The second Class, whose Polypidoms are styled 
Calciferous, are of a calciferous substance, mixed 
with that of animal, and continuing apparent in every 
stage, contains also three Orders ; the first of which 
has, like the Tubularias, the polypi at the extremities 
of the stems and branches, but, being less horny and 
more calcareous, forms an intermediate link between 
the last Order of the preceding Class and the second 
Order of the present Class, whose Polypidoms are 
very cretaceous or chalky, but whose polypi are not 
apparent ; they are articulated. The third Order 
of this Class are not articulated. 
The Polypidoms of the third Class are termed Cor- 
ticiferous : they are composed of two substances, the 
one exterior, and enveloping, named rind , or in- 
crustation ; the other called axe , placed in the centre 
of the first, and supporting it : it is also divided into 
three Orders. The first Order comprehends the 
Spongia, whose polypi are dubious, but decidedly 
invisible. The second includes the genera of the 
