Microscopical Society of Victoria. 
45 
motion is well displayed, while the whole animal frequently bends 
and waves itself about on its pedicle as if moved by some fairy 
wind. This Polyzoon having no cell to retreat to, and being 
exceedingly transparent, affords a fine opportunity for studying its 
internal economy. The currents caused by the cilia were easily 
seen, and were strong enough to draw within reach objects floating 
at some distance, which, if nutritive, were immediately engulfed. 
The course of each particle of food was easily observed throughout 
the operations of mastication and digestion. The motion of the 
stomach was constant, food being continually pouring in, not in 
great quantities, truly, but still with such regularity that its powers 
of feeding seemed enormous. It is probable that at times there 
must be a dearth of food in the surrounding water, else it were 
impossible to understand how this constant absorption failed to 
cause a fracture somewhere, to say nothing of the minor ailments 
of dyspepsia. 
The next species to describe was a Diachoris , the tentacles of 
which, twenty or more, were well displayed. This species 
possesses that truly wonderful appendage called an avicularium. 
In general appearance it is just like a parrot's head with rather 
long beak, the lower mandible open to its widest extent, occasionally 
shutting with a snap, and then re-opening slowly. Sometimes the 
avicularium moves sharply on its stalk, as if pouncing on some 
prey. It moves independently, whether the Polyzoon be 
extended from its cell, or not. The use of this strange organ is 
unknown. Various surmises have been offered by different 
observers, but nothing is certain. I regret to say my observations 
did not help much to elucidate the mystery. On another species— 
Bugula dentata, tentacles, sixteen—the avicularium has a motion 
peculiarly bird-like, and almost continuous. On one occasion I 
saw one with the mandibles closed, grasping a tuft of confervoid- 
like substance, just like a bird with a wisp of hay in its beak. 
This it retained for some days, while the peculiar waving motion 
was still kept up. The only explanation seemed to be that the 
decaying conferva would attract minute infusoria, which would 
thus be brought within easy reach of the tentacles of the Polyzoon. 
Busk says they are organs of prehension, but I confess my inability 
to understand exactly what this means. 
