Madreporarian Subfamily Montiporine. 123 
and, assuming our conclusions to be correct, start from the 
hypothetical parent-polyp of the genus. 
This polyp, as we have seen, differed from that of 
Madrepora, Turbinaria, and Astreopora in that the porous 
theca did not rise up into a cone, but was low and thick, 
filling up, but probably not much overtopping, the rim of the 
epithecal saucer. Primarily the porous walls consisted of 
radial lamin joined together by synapticule *, so that the 
ccenenchyma surrounding this parent polyp may be said to 
radiate outwards towards the edge of the epitheca. When 
the first ring of buds appeared just within the edge of the 
epitheca their walls would also radiate outwards, either con- 
tinuing to be supported by an extension of the primitive 
epitheca or shooting out freely beyond its edge. From this 
initial stage in the development of MJontipora we should 
expect to find the coenenchyma consisting of laminate plates 
standing at right angles to the epitheca and radiating out- 
wards on all sides. We should expect to find this because 
the coenenchyma is nothing but the resultant of fusion of the 
porous walls of the component polyps, and their laminate 
costes would necessarily be arranged in the manner described. 
Now this initial stage in the growth of the Montiporan 
corallum is traceable in almost every type. A surface of 
fracture through any explanate Montiporan will almost inva- 
riably reveal a thin basal layer streaming outwards towards 
the growing edge. While this basal ‘streaming layer” 
is of fairly uniform thickness and the direction of its tibres 
is always outwards—7. e. in the line of growth—its texture 
may vary. (1) It may be composed of ribbon-like bands 
running outwards more or less at right angles to the epitheca, 
but so united as to form a system of flat canals apparently 
freely communicating with one another. ‘This laminate reti- 
culum, occurring as it invariably does in the ‘streaming layer,” 
may, I think, safely be regarded as a vestige of the primitive 
laminate costee which were once the most important element 
in the calicle walls. (2) The primitive band-reticulum may, 
owing to the extensive perforation of the amine, have lost 
this character and have become a filamentous reticulum. In 
this case also the direction of the threads is typically very 
pronounced, streaming outwards towards the growing edge. 
There are, lastly, a few cases in which the reticulum shows 
no special streaming; these would appear to have been 
secondarily modified. Here it should be remarked that only 
* T use this term generally for all outgrowths from the faces of septa 
for their mutual support, irrespective of their form and position, 
