G. FLUSTRA. 
43 
ed with the animals to whose cells their habitation ad- 
heres. There are, however, strong grounds of pre- 
sumption that the more perfect result of observation 
will prove them not excluded from what we deem a 
general and characteristic distinction. When we are 
better acquainted with the Polypidoms, we shall be 
more at liberty to observe the Polypi ; when the atten- 
tion is devoted to one object, its peculiarities are more 
likely to be discovered. 
The Flustras vary much in form ; sometimes they 
appear as simple membranes extended on the fu- 
cus ; others rise in leafy but flat surfaces, lobed or 
entire, sometimes in verticillated branches, the cells 
always contiguous, hexagonal or polygonal, and have 
their partitions perpendicular to the surface on which 
they are established ; the upper part usually convex 
or hemispherical, and formed of a substance more 
membranous, thinner, and more transparent than the 
side partitions, and which usually disappears by dry- 
ing, sometimes so soon after the death of the animal, 
that we are inclined to suspect it either forms part of 
the body or adheres to it. 
When the animal of the Flustra has acquired its 
full growth, it flings from the opening of its cell a 
small globular body, which fixes itself near the open- 
ing, increases in size, and soon assumes the form of 
a new cell : it is yet closed, but through the transpa- 
rent membrane that covers its surface, the move- 
ments of a polypus may be perceived, who delays not 
to burst the enclosure of his little habitation ; then, 
exulting in the plenitude of existence, he exercises 
its functions, and by the assistance of twelve tentacula 
