110 
TRIBE III. MADREPORACEA. 
bou3. Corallum having the cells quite small, punctiform or conical ; septa 
obtuse. 
Plate 55, fig. 5, corallum, natural size; 5a, cell, enlarged. — Feejee Islands. 
— Exp. Exp. 
20. PoRiTES iNFORMis {Dana). — Stout erect glomerate, gibbous lobed, 
and sparingly erose ; polyps pale-yellow, surrounded by brown, tentacles ob- 
solete. Corallum without cells, stars scarcely distinguishable, central pore 
very minute, and surrounded by six granules ; the outer 12 granules scattered. 
Plate 55, fig. 6, corallum, natural size ; 6«, polyps and surface of zoophyte, 
enlarged ; 6 6, cells and surface of corallum, enlarged ; 6 c, part of transverse 
section. — Feejee Islands. — Exp. Exp. 
21. PoRiTES EROSA {Dana). — Stout erect glomerate, columniform, alive 
for 2| inches ; truncate at summit, erose and deeply incised ; lateral surface 
sparingly monticulose, and rarely subcarinate. Corallum without cells, stars 
rather distinct, except at apex, circles of 6 and 12 granules regular. 
Plate 55, fig. 8, corallum, natural size; 8a, cell, enlarged. — Sooloo Sea. — 
Exp. Exp. 
22. PoRiTEs MONTicuLosA {Dana). — Stout erect glomerate, columniform 
or erect lobed, apex round-truncate ; surface every where angularly erose or 
monticulose; lateral monticles crowded, often subtriangular and ascending, 
never coalescing into carinate ridges, the apical a little smaller ; polyps brown, 
the lips semilunate and yellow, tentacles whitish, obsolete, Corallum with no 
cells, stars scarcely distinguishable, central pore very minute. 
Plate 55, fig. 7, corallum, natural size ; 7 a, polyps, enlarged ; 7 h, cells, en- 
larged; 7 c, part of transverse section, ditto. — Feejee Islands. — Exp. Exp. 
23. PoRiTES LICHEN {Dana). — Incrusting, ^ of an inch thick, undulate, 
margin subacute, often flexed upward, and free for a third of an inch : under 
surface smooth, or obsoletely plicate. Corallum having the cells shallow, and 
often prominent in minute, thin ridges, which give the surface a reticulate ap- 
pearance. 
Plate 56, fig. 2, corallum, natural size.— Feejee Islands. — Exp. Exp. 
24. PoRiTES RETicuLOSA {Dana). — Incrusting, undulate, margin scarcely 
at all free, surface mammillate and tuberose. Corallum very porous, cells 
neatly angular, shallow, rather large (| of a line), plane at bottom, septa thin, 
and often prominent in thin ridges, like the lichen. 
Plate 55, fig. 1, corallum, natural size. — Feejee Islands. — Exp. Exp. 
25. PoRiTES ARENACEA {Lamarck). — Incrusting, quite simple. Corallum 
having the cells superficial, subconcave, very small. 
The Red Sea, incrusting the Mytilus margaritiferus, — Lamarck. 
