Madreporarian Subfamily Montiporine. 121 
term ccenenchyma applies, in the Madreporide, to the fused 
porous walls of the individual polyps forming the colony. 
In using the expressions “the calicles lead”’ and ‘ the coenen- 
chyma fills up the interstices,” what is really meant is that 
the walls of the individual polyps are distinguishable as such 
above the level of fusion; where the walls fuse together to 
form the ccoenenchyma they cease to be distinguishable. 
While, then, in the other Madreporide the walls of individual 
polyps are typically recognizable in so far as they keep above 
the level of their fusion, in the genus Montzpora as soon as 
the parent polyp has budded to forma 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 1 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 
ccenenchymatous edge of the rim of the cup in Zurbinaria 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 ccenenchyma as the basis of our classification. 
In so doing we emphasize the fact that the Montipore are 
ecenenchymatouscorals par excellence, that, whereas the coenen- 
chyma of the Madreporide 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 
ismore 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 
