MOLLUSC-LIKE ANIMALS. 



75 



"We have used the name ' moss-animals ' several times. If we study a 

 colony of some of the species, we at once recognize its applicability ; for 

 the multitude of animals, each protruding from its cell, presents a striking 

 resemblance, in all but color, to a bit of moss. Many are the patterns of 

 the animals, while each has a cell peculiar to itself. Possibly most inter- 

 esting of all the structures connected with some of the marine forms are 



Fig. 72. — Xeptune's frill (Retepora). 



the ; birds' heads.' These, as their name implies, are shaped like a bird's 

 head, with its upper and lower mandibles, and under the microscope the 

 student can see, them open and close, now shutting on nothing, now grasp- 

 ing some worm that happens near. Many theories have been advanced as 

 to the functions of these curious bodies, but none that is wholly satisfac- 

 tory. 



The fresh-water moss-animals are common in slowly running brooks 

 and ponds, where they seek the shade, forming delicate branching filia- 

 ments on the under side of stones, or large gelatinous masses on some sub- 

 memed log. One needs to see them under the microscope to appreciate 



