72 CORALS AND CORAL ISLANDS. 



repora cribripora D., a species collected in the Feejees, is rep- 

 resented much enlarged in the accompanying figure. The nat- 



POLTP OF M. CRIBRIPORA, D. 



ural size of the expanded polyp in this genus is generally 

 from an eighth to a twelfth of an inch across the star. The 

 disk of the polyp is quite small, and the number of tentacles is 

 always twelve. The most common color of the polyps is green, 

 while that of the general surface between is ordinarily a pale 

 or a dark umber. In many species of Madrepora the branch- 

 es spread out laterally from a central or lateral trunk, and co- 

 alesce together into a complete net-work, having the form of a 

 shallow vase ; and the interior of the vase is filled with multi- 

 tudes of short, cylindrical coral stems, rising from the reticula- 

 ting branches, which, when alive, have literally the aspect of 

 sprigs of flowers in the vase. 



In certain kinds, closely related to Madreporae, the calicles 

 are reduced to points, or spiniform or angular prominences, or 

 fail altogether, and there are sometimes rounded promi- 

 nences between the cells ; these degraded Madrepores belong 

 to the genus Montipora (Manopora of the Author's Report). 



The genus Dendrophyllia is also referred to the Madre- 

 pore tribe. The budding, as already explained, is of the 

 same kind as in the Madrepores. But the tentacles exceed 

 twelve. One of the polyps of D. nigrescens D., enlarged, is 

 shown in the figure, on page 75. This Pacific species grows to 

 a height of at least three feet, and is peculiar in having a very 





