G. CORALLINA. 125 



niillemetre in leni^th, 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 Araphiroas, 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- 



