186 THE VOYAGE OF H.M.S. CHALLENGER. 
Genus 2. Napopora, Quelch. 
Napopora, Quelch, Ann. and Mag. Nat. Hist., vol. xiii., 1884, p. 296. 
Corallum compound, porous. Gemmation intracalicinal, the developing buds with 
distinct centres, almost destitute of distinct walls, at first united in groups of from two 
to six, and surrounded by the common wall of the parent calicle; but as development 
proceeds, they are separated off by a narrow, raised, distinct wall. Calicinal depressions 
very variable in size and shape, according to the number, position, and degree of develop- 
ment of the buds. ‘Walls of the older calicles porous, distinctly raised, angular. Septa 
generally of two cycles, rudimentary. Pali six, sometimes one smaller than the others 
or absent, generally well developed, and distinctly marking the position of the calicinal 
centres. Columella rudimentary, represented by small, papilliform projections, often 
absent. 
This genus is peculiar among the Poritide in the arrangement of its calicles, which 
present an approach to a meandrine condition. Its closest ally is Synarewa,but in this 
latter genus the walls are not developed. 
Napopora irregularis, Quelch (PI. VIII. figs. 6—6a). 
Napopora irregularis, Quelech, Ann. and Mag. Nat. Hist., vol. xii., 1884, p. 296. 
Corallum ramose; branches rather short, moderately thick, obtuse, and slightly or 
not at all compressed. Calicles very variable, seen in all stages of development, with 
many granular points or flattened projections ; the single calicles with distinct walls, sub- 
circular, about 2 mm. in diameter; the larger ones with many distinct centres in the 
same cavity, surrounded by a common wall, which is raised, angular, and of irregular 
shape, with-a diameter of from 4 to 9mm. Many of the developing centres present no 
trace of a wall, others possess walls more or less incomplete ; but the centres are easily 
distinguished by the position of the pali. The septa of two or three cycles, generally 
twelve, sometimes fewer, rudimentary, sometimes rather distinct at their imner ends, 
and united two by two where the pali are placed. The pali are generally. six in number, 
prominent, sometimes one very small or absent. Columella inconspicuous. 
Of this species there is a single small specimen. It consists of a broken, shghtly 
compressed branch about 5°5 em. long, with three branchlets, one of which is broken 
off. The widest diameter of the branches is about 1°25 em., and of the branchlets 
about 1 cm., even close to the apex. The surface is delicate and easily abraded. The 
species presents an approach to Porites latistellata. 
Locality.—Tahiti. 
