1 6 THE HAUNTS OF LIFE 



OF UNCERTAIN POSITION. There are many 

 seashore animals whose relationships are ob- 

 scure. Thus there are the Polyzoa, to which the 

 common Sea-Mat (Flustra) belongs the ani- 

 mal on which Darwin wrote his first scientific 

 paper. The Polyzoa form a large class, with 

 a great variety of representatives, some sea- 

 weed-like (F lustra) , till you look into them; 

 some coral-like (Cellepora) ; some gelatinous 

 (Alcyonidium] ; some like zoophytes (Gemel- 

 aria), but ever so much higher in structure. 



ECHINODERMS. The prickly skinned ani- 

 ^mals are represented by star- fishes, brittle-stars, 

 sea-urchins, and sea-cucumbers, forming a well- 

 marked " kenspeckle " class, with a great tend- 

 ency to become very calcareous, least so in the 

 sea-cucumbers, most in such sea-urchins as the 

 sand-dollar. It is a most interesting sight to 

 watch the common star-fish creep up the verti- 

 cal surface of a submerged rock by means of its 

 remarkable hydraulic locomotor system, while 

 the sea-urchin, when moving on a flat surface, 

 hobbles along on the tips of its five teeth! 



STINGING ANIMALS. Sea-anemones nestle 

 like flowers in the niches of the rocks. In 



