POLYZOA. 



247 



seized to the mouth of the Polyzoon, and, also, that 

 this latter is situated at the bottom of a funnel of 



FIG. 18 6. CELLTTLARIA AvicuLARiA : a, natural size ; &and c, portions much mag- 

 nified, showing the " birds' heads ;" d, a single polyzoon in its cell. 



ciliated tentacula, and calculated only to receive 

 such minute prey as is drawn within the ciliary vortex, 

 it is difficult to see how this can be effected. Mr. 

 Gosse has suggested a very ingenious explanation. 

 The habit of seizing a passing animal, and hold- 

 ing it with a tenacious grasp until it dies, may be a 

 means of attracting a supply of food into the vicinity. 



