Madreporarian Suhfamily Montiporlnfe. 121 



term cociieiicliynia a|tj)lic.s, in the Ahulreporidaj, to the tu.sed 

 porous walls of the inclividiial ]iolyps forming the colony. 

 In using the expressions " the calicles lead " and " thecoenen- 

 chynui tills up the interstices," what is really meant is that 

 the walls of the individual jiolyps are distinguishable as such 

 above the level of fusion ; where the walls fuse together to 

 form tiie cojncnchyma they cease to be distinguishable. 

 While, then, in the other Madrcporidie the walls of individual 

 polyps are tyj)ically recognizable in so far as they keep above 

 the level of their fusion, in the genus Moniipura as soon as 

 the parent polyp has budded to form a colony, no matter how 

 small, we can no longer speak of any porous walls except 

 theoretically, for, fusing right up to the level of their aper- 

 tures, they together form an expanding mass of coenenchyma. 

 It was this last-mentioned fact that struck Ridley as presenting 

 such a contrast to the method of growth in Madrepora ; but 

 the true explanation of the difference is not to be found in 

 his " centrifugal " and " centripetal " methods of budding, 

 for it is obvious that any generalization affecting a genus 

 which leaves all the more primitive explanate growths out of 

 the reckoning must be unreliable. The true significance of 

 these comparisons will be still further discussed in the section 

 on the affinities of the genus, as will also the fact that the 

 coeuenchymatous edge of the riu) of the cup in Turhinaria is 

 closely comparable with the coenenchymatous edge of a foliate 

 Montipore. 



In view, then, of this great development of the coenenchyma 

 and of its prime importance in building up the Montiporan 

 coralla, we have, it seems, no choice but to utilize the variations 

 presented by the coenenchyma as tlie basis of our classification. 

 h\ so doing we emphasize the fact that the Aloniiporce are 

 coenenchy matous corals 2->a'' excellence, that, whereas the coenen- 

 chyma of the ^ladreporidge is primarily merely the tissue 

 arising by the more or less limited fusion of the porous walls 

 of adjoining polyps to form a mutual support, in Montipora it 

 is more than this. Resulting from the complete fusion of the 

 walls, it has in many cases taken on other functions as well 

 as that of a supporting and cementing tissue, for, rising above 

 the level of the polyp-cavities, it is specialized in various 

 ways for their protection. 



A study of the variations which the coenenchyma presents 

 supports this assumption of its taxonomic importance. The 

 specimens admit of being divided in the most natural way 

 according to the specialization of the coenenchyma. We also 

 have the additional satisfaction of finding that transition 

 forms reveal the lines along which the leading specializations 



