CORAL-MAKING POLYPS. 45 
aninal tissue over the outside of the corallum, excepting at 
its upper extremity, above this calcareous coating, 
Another form of a corallum, the secretion of a single 
polyp, is illustrated in the following figure of a species of the 
Fungia family, so-called in allusion to a resemblance to the 
mushroom. ‘The long mouth occupied a considerable part of 
the longitudinal central line. From the line at the centre, 














CTENACTIS ECHINATA, AG. 
there is the same radiated arrangement of calcareous septa 
as in the preceding species, though the animal differs greatly 
in its extreme shortness in proportion to the breadth. The 
corals of this group are also peculiar in having the radiated 
upper surface flat, or nearly so, instead of concave. The fig- 
ure is a fourth the natural size. These corals, of the genus 
Fungia, often exceed a foot in length; and thus coral animals 
are sometimes as large as the largest of Actinie. 
Another species of this genus, the Hungia lacera V. (for- 
merly Pungia echinata D., trom the Feejees), is represented as it 
appears when living (excepting a part left off to suit the page) 
in the following figure. The coral in the perfect state of the an- 
imal, is wholly concealed, though often showing the points of the 
teeth of the septa in consequence of the skin being broken. 
