G. CORALLINA. 
125 
millemetre in length, which had a movement peculiar 
to themselves : they disappeared with the slightest 
agitation of the water, or when the Polypidom was 
exposed to the air; in the latter case I was never 
able with the strongest magnifier to discover the 
slightest remains of these filaments, the point they 
had been attached to, or the cells they might have 
issued from, supposing them to have been polypi. 
This however remains doubtful, as it was only in 
spring I ever observed them, and then only on a few 
particular individuals : I never could discover them 
in winter. 
We frequently observe in the Janias and Coralli- 
nas small globular bodies, more or less volumi- 
nous, and varying in their substance ; the tubercles 
that are found on the Amphiroas, the Halimedas, 
the Udoteas, and the Melobesias, appear analo- 
gous. Ellis imagined them air-vessels to support 
them in the water; but these vesicles are rarely 
empty. I have frequently found them solid, or filled 
with small grains of an unknown nature. They are 
more probably ovaria, enclosing the germs of future 
Polypidoms. All the flexible Polypidoms appear 
thus to multiply. 
The Polypidoms for which I have reserved the 
generic name of Corallina, have always articulated 
stems, more or less compressed, more or less 
branched, and constantly trichotomous. Their co- 
lours when fresh generally incline to red or purple ; 
exposed a very short time to* the action of air, light 
and humidity, they display a variety of hues, each more 
brilliant than the other, from the lightest or the bright- 
