Madreporarian SuhfamVy Montlporinae. l27 



tliem nitli tin- rntiroly diffcront tra1)orul;v of Poritca^ and 

 accordingly placed Montipora among the PoritidiB. So far 

 as my own observation goes, the two are morphologically 

 distinct ; the trabecular in Poritcs are ))rimitive structures, 

 rising straight up from the opitheca, while in Montipora they 

 are, as wo have seen, quite secondary. 



Turning from the coenenchyma to the polyps, polyp- 

 cavities, method of budding, atid to the forms of the corallum, 

 points which arc, as a rule, of prime importance, wc find that 

 the special development of the coenenchyma has, as it were, 

 overshadowed them. With regard to the last-named, we 

 find all the typical methods of growth in each of the four chief 

 divisions based upon the specializations of the cnencnchyma. 

 The polyps themselves are minute and tlieir tentacles are 

 little more than papiliaj or crenulations of the edge of the oral 

 disk. The polyp-cavities are also very small and the septal 

 apparatus as a rule degenerated into mere vertical rows of 

 projecting spines. The largest or directive septum with a 

 few of the larger primaries may be more or less intcrrujitedly 

 laminate. I look upon these as survivals of a primitive lami- 

 nate condition of the septa and costse in the thick porous walls. 

 The cause of this degeneration of polyps and septal apparatus 

 may perhaps be correlated with the great development of 

 the ccenenciiyma, the production of which must be a strain on 

 the resources of the living organism, leading to the fixation of 

 the polyp at a very undeveloped stage. In contradistinction 

 to this extreme we may cite in support of our suggestion the 

 cases of the Alcyonaria and Actinia^ in whicii the polyps 

 reach a very high level of development, while the skeletal 

 matter deposited is either scanty or altogether absent. 



The character of the budding, as also a few furtiier points 

 on the degeneration of the septal apparatus, will be referred 

 to in the concluding section on the interrelationships of the 

 Madreporidai. In that connexion such matters can be more 

 advantageously discussed comparatively. We shall there also 

 summarize the description of the genus above given, and in 

 that way emphasize the arguments in favour of classing 

 Montipora with the Madreporidce. 



The Genus Anacropora. 



This genus, founded by Ridley in 1884 (/. c.) to contain a 

 branched coral from Keeling Island, was said to be distin- 

 guished from Madrepora by the method of budding and from 

 Montipora by its protuberant calicles. 



The method of budding in Madrepora, in which smaller 



