POLYNESIAN PORITES 29 
of the two shows its relation to the Mycediwm, both fresh and corroded fragments of which 
adhere to the specimen. The larger, a, no longer shows its attachment, but it is essentially 
of the same shape, and small encrusting portions of a Mycedium are still attached to it. 
Whether this Porites always grows in association with Mycediwm we have no means of 
knowing. The growth-form of both specimens is clearly due to this fact. The calicles are very 
different from those of both the other known Porites from the Society Islands. The spirit 
specimen is from Papeete. 
Of morphological interest are the large vertical pores running into the walls. Somewhat 
similar pores appear in P. Tonga Islands 1 (see Plate I. fig. 7); but in that case they are more 
obviously the portions of interseptal loculi cut off by the outermost ring of synapticule. 
a. A lobate colony, 10 cm, high, 6 x 10 across the top. Zool. Dept. 86. 12. 9. 291. 
b. A young colony, showing method of attachment to Zool. Dept. 86. 12. 9. 364. 
the Mycedium. 
c. A rounded colony, with a fragment (in spirit). Zool. Dept. 80. 11. 25. 220 (part). 
2. Porites Society Islands (352, (P. Sociorwm secunda.) (Pl. X. fig. 4.) 
[Tahiti,* coll. H.MLS. ‘Challenger’ and Museum Godeffroy ; British Museum. ] 
Syn. Porites latistellata Quelch, Chall. Rep. xvi. (1886) p. 185, pl. xi. figs. 6, 6a. 
Napopora irregularis Quelch, Chall. Rep. xvi. (1886) p. 186, pl. viii. figs. 6, 6a. 
Description —tThe corallum rises from a small explanate base into close tufts of stems, 
which are often united to one another both by fusions of the stems themselves, and also by 
the outgrowth of free explanate edges from their sides. The stems are of different shapes, 
either short, angular, and flat-topped, or long, thin, flabellate, and rounded, The tufts are 
‘symmetrically round-topped and about 12 cm. high. 
The calicles are about 1°2 mm. in diameter, but are very ill-defined, often mere shallow 
breaks in a skeletal texture composed of flat flakes which run out into frosted points. The 
walls are very broad, but throw up a usually sharp median ridge above the flakes. This ridge, 
which runs round single calicles, or sometimes encircles two or three at a time, shows every 
variation in texture, from flakes perforated with pores to a fine foaming filamentous reticulum, 
e.g. at the growing tips. When these ccenenchymatous wall-ridges are sharp and high, the whole 
surface of the stem is ragged and fluffy. The septa are very irregular, and are mostly tongues 
of the wall flakes, sometimes broad, sometimes narrow and much twisted. In the younger 
calicles the typical septal formula can at times be made out, but in older calicles the texture 
becomes more strikingly flaky, and the radial symmetry is obscured. The ring of pali is often 
visible to the naked eye as a boss, but under the lens the individual pali are frequently difficult 
to distinguish from the general tangle of the intra-calicular skeleton. The interseptal loculi 
vary in width, according as the septa are narrow or broad; they seldom run deep into the coral. 
In section vertical trabecule are seldom seen, the coral being built up of a confused 
reticulum in which horizontal elements are sometimes conspicuous. 
* The ‘Challenger’ specimen c is from the “ Papeete reefs.” 
