Madreporarian Subfamily Montiporine. 129 
from Montipora, we may assume that the protuberant calicles, 
which may, in some cases, be even tall and conical, suggest 
that this branching off took place at a very early stage in the 
development of that genus. ‘That these protuberances are 
primitive, and not secondary returns to primitive conditions, 
may, perhaps, be gathered from the very important fact that 
the primary septa in the more protuberant calicles are 
laminate, and, further, that these laminate radial structures 
may even project down the outer wall of the protuberance as 
costal ridges (PI. II. fig. 5). It is specially worthy of note that 
the less protuberant calicles, or those which open flush with the 
surface, have the degenerated septal apparatus characteristic 
of Montipora, while those which grow taller and_ slightly 
larger develop radial skeletal lamine, septa and coste. 
While it is of course quite possible that this is a secondary 
return to primitive conditions, there is no reason why we 
should not assume it to be the persistence of such conditions. 
The burden of proof, I think, rests with those who prefer the 
former suggestion. 
I have been much struck by noting that many of the pro- 
tuberant calicles with costal ridges running down their sides 
show the tendency to a spiral twisting ot the whole calicle 
which I have already referred to in Zurbinaria and Madre- 
pora. ‘This fact, again, seems to me to suggest that the 
protuberance of the calicles is primitive and not atavistic. 
Hence, then, we conclude that Anacropora branched off 
from Montipora before the degeneration of the calicles and of 
their laminate radial skeleton had gone as far as it now has 
in the latter genus. 
In this connexion it is worth noting that the axial streaming 
layer is typically laminate or band-like, and that, in those 
cases in which it appears most filamentous, examination 
shows that this is a secondary condition due to the formation 
of large perforations in the primitive longitudinal bands. 
This band-reticulum, as we have seen above, can be best 
traced to the outward streaming of the primitive laminate 
radial structures composing the chief portion of the thick 
walls of the parent and daughter polyps in the earlier stages 
of colony formation. 
In addition to this important laminate structure of the 
walls of the more protuberant calicles, the method of branching 
is quite peculiar. All the known types are composed of 
rather thin cylindrical stems more or less knotted (by the 
protuberant calicles) like a thorn-stick. While the stems 
are generally slightly curved, the branches come off suddenly 
at rather wide angles, the stem at the same time bending 
