ZOOPHYTES. 387 



tlie smallest possible warts or protuberances denticula- 

 ting the dilated tip. But the additions are still more 

 peculiar. From the middle part of the column a 

 number, from four to nine, of great oval sacs pro- 

 iect, each attached by one end, while the other 

 stretches out horizontally, thus surrounding the slender 

 column. Each of these sacs is an ovarian capsule, and 

 contains several ova of a brilliant yellow or crimson 

 hue. Thus we have the second form, — that of the 

 reproductive polypes. 



In some places single ovarian capsules stand np 

 alone from the fleshy carpet, agreeing in every respect 

 with those which we have just examined, except that 

 they are sessile, instead of being carried by a polype. 



The fourth form is that of the tentacular polype. 

 Here and there, from amidst the forest of shorter 

 polypes, — alimentary and reproductive, — white tlireads 

 are seen protruding, which extend to a length four 

 or five times as great as theirs, and hang down or 

 loosely float in the water. They are found on the 

 outskirts of the whole comj^ound structure, and at 

 each extremity of the long diameter of the mouth of 

 the supporting shell, so that they must, in their 

 natural condition, reach to the ground, along which 

 the crab-tenanted shell is carried, enabling the Zoo- 

 phyte to seize and appropriate the atoms scattered by 

 the crab whenever he takes his meals. The tips of 

 these organs are covered with a dense pavement ot 

 large thread-cells ; and they must doubtless perform 

 the ofiice of general purveyors to the composite 

 animal. 



But still more remarkable, more extraordmary than 

 all we have been considering, are the objects which 



