REPORT ON THE REEF-CORALS. 183 
short and not at all prominent. - Columella very small and generally inconspicuous, often 
absent. Surface very granulated and minutely spinulous. Texture of corallum rather 
dense and heavy, closely reticulate or fissured. 
In general appearance this species somewhat resembles Porites astrxoides, but its 
structure is quite different. A single small specimen was obtained, 
Locality.—Kandavu. 
11. Porites arenosa (Esper). 
Madrepora arenosa, Esper, Pflanz. Forts., i. p. 80, Madrep. pl. lxv. 
Porites arenosa, Milne-Edwards and Haime, Cor., iu. p. 180. 
This widely distributed species is represented by numerous specimens. It is very 
close to Porites lutea, but seems to be sufficiently distinguishable by the much more 
lobed and mammillated corallum, by the very thin and small, elongated cells in the 
depressions, by the deeper cells with very conspicuous interseptal spaces, by the longer 
and thinner pali, and by the more spinulous walls. 
Localities.—Tahiti ; Tongatabu; Banda; Kandavu, and other reefs, Fiji, 
12. Porites gaimardi, Milne-Edwards and Haime. 
Porites gaimardi, Milne-Edwards and Haime, Cor., iii. p. 179, 
A single specimen was obtained. It forms a thick, erect, rather elongated mass, 
slightly flattened above. The cups are about 1°5 mm. wide, and the columella is very 
distinct, though small. 
Locality. —Banda. 
13. Porites crassa, n. sp. (Pl. XI. figs. 2-2a). 
Corallum massive, uneven, irregularly monticulose and mammillate, incrusting at the 
base. Calicles deep, moderately large, from 1°5 to 2 mm. wide, not plane at the bottom ; 
walls spinulous, sometimes thin, but generally very thick and porous, being about one- 
fourth or one-half the width of the cell; young developing cells very abundant on the 
thick walls. Septa subequal, often rather thick and prominent, joined two and two in 
the depth of the cup, where a very distinct circle of well-developed, rather long, generally 
thin and pointed paliis visible. The interseptal spaces very wide and distinct. Columella 
absent or quite inconspicuous, Texture very porous but firm. 
This species has many points of resemblance with Porites fragosa, but differs 
markedly in its deep cells which are not plane at the bottom, and also in its thicker walls 
and larger cells. A single small specimen was obtained. 
Locality.—Reefs, Fiji. 
