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REPORT ON THE REEF-CORALS. 185 
17. Porites mirabilis, n. sp. (Pl. XI. figs. 5-5q). 
Corallum massive, convex and gibbous, incrusting at the base. Calicles very unequal, 
of two distinct sizes, with many intermediate ones ; the smaller more numerous, from 
1 to 1°5 mm. wide, sub-polygonal, nearly superficial, but slightly excavate, with rather 
narrow, acute walls, often thickened and very porous, with very thin septa, five or six 
unequal, distinct, long pali, and a styliform columella. The larger calicles often closely 
gathered together, but generally separated by from two to five smaller ones, about 
2°5 mm. wide, sometimes more, much more excavated than the small ones, with very 
thin and closely placed septa of three or four cycles, the fourth cycle being incomplete, 
with from twelve to sixteen, or more, thin and distinct pali surrounding a styliform, or 
subtrabeculate, or porous columella. Texture close and firm, very finely reticulated. 
A single small specimen, nearly 8 cm. in diameter, was obtained. Il is easily dis- 
tinguishable from all other known species of the genus, though an approach is made to it 
by Porites porosa and Porites excavata, from the West Coast of America. 
Locality.—Mactan Island, Philippines. 
18. Porites latistellata, n. sp. (Pl. XI. figs. 6-6a). 
Corallum incrusting at the base and almost massive, becoming subramose or deeply 
lobate above, the lobe-like branches being from about 1 to 2 cm. thick, about 2 cm. long 
at the outer part of the colony, but very short and almost suppressed towards the central 
portion ; slightly swollen and fragile at the apex, subtruncate, very coalescent and often 
compressed. Calicles angular, large, about 3 mm. wide; towards the basal parts they are 
often smaller, and almost or quite superficial, the walls being very thin, acute, and 
slightly raised, often almost indistinguishable ; towards the apical parts the calicles are 
deeper, and on the subtruncate ends they become much excavated, though never as deep 
as they are wide, with very thin, acute, subcircular or elongated walls. Septa from 
twelve to sixteen, often rather indistinct, joined at the centre, and ragged, bearing 
numerous paliform lobes; in the superficial calicles they are rather distinct, with from 
six to eight small pali surrounding a porous columella; in the deep calicles they are often 
almost indistinguishable, very porous and trabeculate, while the pali form a distinct, 
cireular, raised, trabeculate mass nearly confluent with the columella. Texture exceedingly 
light and loosely porous, surface very spinulose and granulated. 
In the shape of its cells the species has much in common with Porites favosa; while 
many of its essential characters indicate an approach to the genus Napopora. A rather 
large specimen was obtained. 
Locality.—Tahiti. 
(ZOOL, CHALL. EXP.—PART XLVI,—1886. ) Zz 24 
