236 
CLASS III.— ORDER III. 
articulations of the twigs are longer than those of the 
branches. 
SLENDER. 
3. Isis gracilis. Base laciniated ; stem and branches 
cylindrical, the latter few in number ; stony articula- 
tions of the stem sometimes near each other, some- 
times distant, those of the branches very long ; both 
kinds translucent, sleek, white, and larger than the 
homy ; the rind unknown ; height two decimetres.— 
Plate 18. fig. 1. 
Antilles. 
ADEONA. 
Stem articulated like the axe of the preceding 
Isideas, surmounted by a fan-shaped expansion, that 
is strewed on both surfaces with very small scattered 
cells, and pierced with round or oval oscules. 
The organisation of the stem of the Adeonas being 
exactly similar to the axe of the Isideas, has induced 
me to place them under the same order, though some 
peculiarities of character might seem to exclude 
them from that division. And here it may be proper 
to observe, that this genus appears in the most na- 
tural manner to unite the Coralline and flexible Po- 
lypidoms with those Polypidoms that are wholly 
stony : in fact, we can only compare it to a Millepore, 
fixed to the axe of a Mopsea or an Isis. And although 
