276 MADREPORARIA. 
Observations on these cwncenchymatous forms.—The foregoing analysis now for the first 
time assigns these forms a place in the morphological series. The variations which they show 
among themselves are interesting. We note for instance that the additional costal trabecule 
may be fairly uniform in numbers over the whole of a colony, or they may be here numerous, 
there altogether wanting, on different parts of one and the same colony. Again, they may be 
as well developed as those in the interior of the calicle (the pali, ete.), or greatly reduced and 
obscured, the horizontal elements then being pronounced ; and lastly together with the horizontal 
elements, they may form a delicate streaming reticulum, filamentous or flaky, which carries the 
walls up into papille. 
On the small size of the calicles seen, with but few exceptions (e.g., P. Society Islands 2, 
P. Fiji Islands 5), in these coenenchymatous forms, compare the observations on Tables B 
and C, p. 284. 
B. The forms in which one ring of extra, intervening, or costal trabecule appears 
typically in the walls. 
This extra ring of trabecule forms the middle line of the walls between adjacent calicles, 
and within it we have the following typical rings: the wall, the septal, and the palic 
trabecule, represented at the surface by granules. Variations in the development of these 
seem to be as follows— 
a. The extra trabecule may rise as a tall, thin, membranous wall, the “ wall” trabecule 
proper remaining low. The septal trabeculae seem to function as the pali, only they are then 
12 in number, and the ordinary pali remain aborted, or appear in traces, sometimes as 
occasional pieces uniting two of the “septal” pali. i 
b. The extra trabecule are not conspicuously the chief constituents of the dividing walls, 
and the pali are not aborted. 
a. The extra trabecule seem to function as the wall trabecule do in single-walled forms, 
thus giving an extra ring of trabecule to the two usually present within the calicle. 
If this interpretation is correct it is most remarkable, and represents the largest type 
of calicle in the genus. From this downwards all the subsequent divisions show 
progressive diminution, ending in GC, 8, v. 
P. Fiji Islands 4. In the text the septal ring of 12 was mistaken for divided 
pali. The true pali occasionally appear distinct from these “septal” pali. 
P. Ellice Islands 5. The true pali are somewhat more frequently developed than 
in the last form, and then sometimes form a separate inner ring, and 
sometimes unite the septal granules into V-shaped processes. 
P. Ellice Islands § 
P. Ellice Islands 9 
P. Ellice Islands 10. This seems to be a variation of the same, but with 
minute deep calicles, with the wall-, septal, and palic granules very closely 
packed. 
P. China Sea 16. The walls are variable, being sometimes reticular, but with 
extra- and wall trabecule traceable; within this the 12 septal granules are 
small and distinct; pali only in traces. 
re present two interesting variations on the above. 
