278 
Transactions of the Society. 
tissue depending from it posteriorly, with the apparently double con- 
tractile vesicle as another characteristic feature. 
The outline of the accompanying figure was sketched with the 
camera lucida during a momentary pause in the animal’s movements, 
and shows the body slightly contracted and widened anteriorly. 
The mastax is protrusible, and the trophi snap and nibble, but 
. the creature not rarely takes the end of an algar filament into the 
oral aperture, when the trophi gnaw at the object at the animal’s 
ease. The food seems usually to be the soft and decaying flocculent 
matters at the bottom, where the animal appears to delight to be,, 
and whence it is generally taken. 
