172 PRACTICAL ZOOLOGY. 



tending so far inward as the stomach. Each tentacle 

 communicates with one of these radial compartments, and 

 is to be regarded as a mere extension of part of the body 

 cavity. 



Alcoholic specimens should be sliced transversely and 

 longitudinally. In a transverse section of the lower part 

 of the body there will be seen the body wall with a series 

 of partitions extending inward and ending in a free edge. 

 The section across the upper part of the body shows an 

 outer circle, the body wall, an inner circle, the stomach 

 wall, and, connecting the two, the radially arranged parti- 

 tions, or mesenteries. Like the hydroids, the sea-anemone 

 is well provided with lasso cells. 



Food is taken into the mouth, digested in the stomach, 

 then passed, mixed with sea water, into the body cavity, 

 through which it is made to circulate by the contractions 

 of the body walls. The indigestible portions of the food 

 are expelled from the stomach through the mouth. 



The tentacles are often brilliant and variegated in color ; 

 and when the sea-anemone is expanded, it well proves the 

 fitness of its name. For a very interesting description of 

 these beautiful animals read Mrs. Agassiz's little book, " A 

 First Lesson in Natural History " (No. IV. in " Guides for 

 Science Teaching "). 



CORAL POLYPS. 



The coral polyps are similar to the sea-anemone in their 

 general structure. They usually grow in colonies with 

 their bases connected by a continuous layer of living 

 matter, from which the polyps grow by budding. 





