HYDROID ZOOPHYTES. 57 



agreeable intruding bodies. When the ciliary action is in- 

 sufficient to effect this, the little filmy creature will succeed 

 in getting rid of the offensive object by suddenly withdraw- 

 ing and jerking itself sidewise, or by bending in one of its 

 ciliated arms, and sending it out with a fillip-like motion. 



Anguinaria spatulata. 



Snake-headed Coralline. — This little Zoophyte winds up 

 a seaweed as the ivy does the oak. It consists of a stem 

 with cells thrown out at intervals on bended stems. They 

 are of a flattened, oval form, and not unlike the head of 

 a snake, open at one side. Each " snake^s head " forms 

 the habitation of a polype, which, when it throws out its 

 own head, presents a circidar crown of tentacula. The 

 neck of the cell-stem is marked with rings, while the 

 swollen head is dotted. The mechanism of the cell is 

 very curious, being furnished with a little door, which, 

 closing when the polype is retracted within its cavity, and 

 held firmly down by muscles, gently opens on its hinges 

 and turns back as the living film passes out and spreads 

 its crown of feelers. All the time it keeps out, the door 

 is folded back, again gradually closing as the animal 

 retires. If a piece of bladder were stretched over a half- 



