104 MADREPORARIA. 
87. Porites Sandwich Islands 7. (P. Hawaiensis septima). 
(Pl. X. fig.1; Pl. XII. fig. 6.) 
[Honolulu, coll. H.M.S. ‘Challenger’; British Museum.] 
Syn. Porites compressa Quelch (non Dana) Chall. Rep. xvi. 1886, p. 180. 
Description —The corallum rises from an encrusting base into long, irregular ridges or 
crests, each 3 cm. high, and from 1 to 1°5 em. thick, with smooth, flat, arched, or slightly 
over-hanging tops. The sides of the ridges are wavy. The ridges meet and fuse. The lower 
edges encrust the living layer, and are rarely free. 
The calicles on the flat tops of the crests develop as shallow indentations in a delicate 
stroma of filamentous reticulum, with wide rounded meshes. ‘The reticulum forms the walls 
which, except in the angles, are very thin; the septa are thin and lamellate, and soon join a 
central columella of open filamentous reticulum, similar to that of the walls. This columella 
reaches to the level of the wall. There are no traces of pali. 
The ordinary lateral calicles are very angular, with conspicuous radial symmetry, about 
1 mm. across, and are crowded and shallow. The walls are thin and sharp, and ragged rather 
than toothed. They rise slightly everywhere in continuous sharp edges above the level of the 
intra-calicular skeleton. In the angles they may thicken into small raised masses of reticulum 
in which young calicles may develop. The septa are of the same thickness as the walls, and 
show a strong tendency to be lamellate. Starting just below the edge of the wall, they rise a 
little, somewhat irregularly, to form a ring of septal granules, obscure in the young calicles, 
but pronounced in the adult, and giving them a ragged appearance. The septa meet and 
appear to fuse completely, but the triple fusion is not really completed—it is rather a fusion of 
the septa with the columellar tangle. Hence we have the complete palic formula, the pali 
being as inconspicuous as the septal granules, and mere ragged points on the edges of the 
septa. The columellar tangle forms a ring, and mostly develops a few cross strands from 
which a flattened columellar tubercle rises not quite to the level of the pali. The inter- 
septal loculi are open, but hardly conspicuous or sharply defined, owing to a frosting of the 
sides of the septa. 
This coral was identified by Quelch with Dana’s Porites compressa, but the whole method 
of growth in Dana’s type was much more definite, and there is no evidence in the latter of an 
encrusting base, nor do the calicles appear to agree, judging from the indistinct drawing 
given in Dana’s atlas. 
I was at first inclined to think that the coral might be only a special growth of that last 
described from the same locality, but the walls in that coral are much higher and the septa 
more distinct, and appear to end freely round an open fossa, This is apparently another case 
of members of a genus from the same locality having a strong “ family likeness,” 
