CYCLOUM. 365 
uniformity and quickness which is admirable, and very 
pleasing to the beholder. When the egg is at rest, their 
velocity is not diminished, excepting at the will, so to 
speak, of the ovum, for it may be seen to become slower 
and less constant, to cease entirely for a moment, and again 
be renewed with its former force. The egg, at rest, will at 
once start from its place, and swim about hither and thither, 
as it were endowed with volition, turning on its axis fre- 
quently, moving sometimes on one side, sometimes on the 
edge, when the cilia become invisible. By their motion 
they drive a current of water over the surface.” 
3. ALCYONIDIUM PARasITicuM, Dr. Meming. 
Hab. On the stalks of Sertulariade. 
This is like a blackish-brown earthy coating on several 
of the corallines. The doubts respecting its nature have 
been dispelled by the researches of Mr. Hassall, Van Bene- 
den, and Professor Reid. An interesting account of it by 
Professor Reid may be found in Dr. Johnston’s work, page 
362. 
Genus XXI. CYCLOUM, Hassall. 
Gen. Char. Polypidom fleshy, encrusting, covered with nu- 
merous imperforate papillee.— Hassall. 
