166 



THE MECHANICAL FUNCTIONS. 



of a honey-comb, as is seen in the magnified 

 view of them, Fig. 64. 



In other tribes the inorganic base of support 

 is internal, constituting a kind of skeleton or 

 axis; the polypous mouths being spread at in- 

 tervals over the surface of the fleshy layer which 

 covers this skeleton. This is the case with the 

 Goi'ooiiia, Atitipathes, and the Coral, which ex- 

 hibit still closer resemblances to the branched 

 forms of vegetable stems. The flesh contains 

 granules of calcareous matter, which, in the 

 dried specimens, adhere to the surface of the 

 stems. Fig. 65 is a branch of the Corallium 



rnbnim, of which Fig. 66 is a magnified portion, 

 showing the appearance of the polypes in their 

 expanded and contracted states. The way in 

 which the polypes are embedded in the flesh is 

 seen in Fig. 67, which represents a section of the 

 Gorgonia Brtaretis. 



In many cases the polypes are lodged in cup- 

 like depressions in the surface of the calca- 

 reous axis, which aflbrds them some degree of 

 protection. In Madrepores these depressions 



