150 



Dr. J. E. Duerden on the 



closely similar to those oblained from the three preceding 

 species tliat it is unnecessary 1o repeat them. In every case 

 the mesenteries above tlie usnal number — twelve pairs in two 

 cycles — are arranged in conformity wiili the first and second 

 cycles, not in new cycles; and tission separates an enh\rged 

 polyp into two halves, eacli with twelve pairs of mesenteries, 

 in every way recalling ordinary bud-polyps. 



Fig. 6. 



Septal arrangement in three dinerent calices of Solemftreea hi/ades. a, 

 as met -with in most calices ; b, an enlarged calice ; c, a calice in 

 process of fission. In h and c the se[>ta are arranged ( n the same 

 plan as in n ; in c the septa are nearly double in nuniber those present 

 111 an ordinary calice, so that wheii fission is completed each half 

 ■will represent a new calice. 



Thus in fission of the enlarged polyps of three gemmiferous 

 genera — Acropora {Madreporu) , Pontes, and Cladocora — 

 it is manilest that the resulting polyps are in every way 

 comparable with polyps produced by ordinary budding; 

 these, in their turn, by the presence of directives and tlie 

 retention of the hexameral cyclic plan, resemble larval polyps. 



