44 
CLASS L— ORDER I. 
that surround his mouth, he gives a rotatory motion 
to the water, and involves in this diminutive whirlpool 
the animals on which he feeds . 
The color of the Flustra is in general a lighter or 
a darker fawn ; sometimes they incline to red, or grey ; 
but they never assume those brilliant hues which are 
seen in the Corallines and Sertularias. 
Left to themselves and without support, I know no 
species that exceeds two decimetres in height ; but at- 
tached to the leaves, or surrounding the branches of 
the great Thalassiophytes, they envelop these in a 
cretaceous covering, which sometimes extends itself 
over the whole plant. 
The Flustras are found in all seas, and in all depths, 
on the marine plants of the deepest waters, as well as 
on those that are scattered on our shores; in the 
neighbourhood of the polar ices, as well as under the 
burning sun of the tropics. 
The seas of former periods enclosed them in their 
bosoms, as well as the Cellepores ; and their impres- 
sions, or their fragments, are discovered in those cal- 
careous rocks that are anterior to chalk formations. 
FOLIACEOUS OR LEAFY. 
1. Flustra foliacea . Branching ; divisions fan 
and other shapes. 
Seas of Europe* 
TRUNCATED. 
2. Flustra tr uncat a. Leaf-like and dichotomous ; 
divisions linear and truncated* 
Seas of Europe. 
