ZOOPHYTES. 45 



" arms," it is able to take hold until it has " looped " like a 

 geometer caterpillar, by bringing its footstalk forward and 

 taking fresh hold. The extremities of the eight arms (or ribs 

 of the sunshade) are ornamented with tassels of 

 tentacles, and it uses these after the manner of 

 a sea anemone when it wishes to secure food. 

 It, in fact, has some of the peculiarities of both 

 jelly-fish and anemone, though it will not act 

 quite consistently with either character. I have 

 found it on Laminaria and other weeds at low 

 water, and a few months since I picked one off 

 ^ e pl uma g e of a dead guillemot, that had been 

 drowned in a storm and afterwards washed ashore. 

 There is an important group of incrusting organisms that 

 you will find represented on almost the first specimen of FJJCUS 

 you pick up, and which you may be tempted to class with these 

 zoophytes ; but they occupy a much higher position in the 

 scale of life. I refer to the Sea-mats, the Sea-scurfs, the 

 Bird's-head Coralline, and allied forms, whose proper designa- 

 tion is Marine Rolyzoa. They are more nearly allied to the 

 mollusks, the structure approaching towards that of the Lamp- 

 shells. They are associated in colonies (zoarid), but there is 

 no connecting ccenosarc as in the Hydrozoa, although there is 

 communication between the chambers by wisps of animal 

 matter. Each chamber of the Sea-mat marks the habitation 

 of a complete individual, who catches, eats, and digests for 

 himself alone, not for the colony. These chambers are of a 

 horny, persistent character, secreted of course by the poly- 

 pide ; with a small opening through which the creature 

 protrudes its mouth and fringe of tentacles. Its body consists 

 of a thin bag filled with a clear fluid, in which can be traced 

 the gullet enlarging into a simple stomach, contracting again 

 into the intestine. There are muscles by means of which the 

 upper part of the sac with the mouth and tentacles are with- 

 drawn inside the lower part Add to this a nerve -ganglion 



