236 CLASS m.—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 



