CCELENTERATA. 



253 



Fig. 201. — Madrepora a^era, living and expanded; natural size. Pacific. 



whose mean temperature in the coldest month is below 

 68° Fahr., nor at greater depth than twenty fathoms. The 

 most luxuriant reefs are in the Central and Western Pa- 

 cific and around the West Indies. 



Fig. 202. — Ctenactis echinata, or "Mushroom-coral ;" one fourth natural size. Pacific. 



