CORAL-MAKING POLYPS. 



45 



animal tissue over the outside of the coralluin, excepting at 

 its upper extremity, above this calcareous coating. 



Another form of a corallum, the secretion of a sinde 

 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. Prom the line at the centre, 



CTENACTIS ECHINATA. 



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 Actiniae. 



Another species of this genus, the Fungia lacera V. (for- 

 merly Fungia echinata D., from 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. 



