CCELENTERATA. 
255 
Fig. 205 .—Astrcea rotulosa. West Iudies. 
The main kinds of reefs are fringing , where the reef is 
close to the shore; harrier , where there is a channel be- 
Fie. 206.—Cell of Madrepore Coral, 
magnified. The cup-like depres¬ 
sion at the top of a coral skeleton 
is called calicle. 
Fig. 207 .—Fragment of Red Coral ( Coral- 
Hum rubrum), showing living cortex 
and expanded Polyps. Mediterranean. 
