108 
TRIBE III.~MADREPORACEA, 
6. PoRiTES RECTA (Lesueiir), — Cespitose, alive for 1 to IJ inches ; branches 
straight, remote, somewhat compressed, divaricately furcate, rounded at sum- 
mit ; polyps salient, cylindrical, tinged with brown ; tentacles short. Coral- 
lum rather porous, the cells small, excavate ; rays denticulate. 
St. Bartholomew and St. Christopher’s, West Indies. — Lesueur» 
7. PoRiTES DivARiCATA [Lesucur). — Cespitose, alive for 1 to inches ; 
branches quite slender (3 to 4 lines thick), somewhat compressed, divaricate 
and flexuous, sometimes reflexed; apex rounded, often furcate. Corallum 
fragile ; cells small a line broad), excavate. 
Guadaloupe, West Indies. — Lesueur. 
8. PoRiTES NiGRESCENS {Dana). — Ramose, cespitose, alive for 6 or 8 inches ; 
branches elongate, rather crowded, sometimes coalescing, flexuous, subterete, 
gradually tapering, obtuse ; stems occasionally 1 to H inches thick at base, 
branchlets ^ to ^ an inch thick and 2 to 2^ inches long. Corallum firm ; cells 
rather large, scarcely excavate or superficial ; septa broad and granulous. 
Plate 54, fig. 1, corallum, natural size ; 1 a, surface with the cells enlarged ; 
16, transverse section, enlarged. — Feejee Islands. — Exp. Exp. — Yai.mucro- 
nata, plate 54, fig. 2 ; Sooloo Sea. 
9. PoKiTES PALMATA {Dana). — Cespitose, alive for 3 or 4 inches ; branches 
broad flabellate, sometimes 2 inches broad, J thick, and short-lobed or digitate 
at apex ; below often coalescing, lobes compressed, i to 1 inch long, obtuse, 
occasionally elongate and terete. Corallum somewhat fragile ; cells superfi- 
cial or slightly excavate, small (half a line); septa about the upper parts 
of the branches acute. 
Plate 54, fig. 3, corallum, natural size ; 3 a, cells, enlarged. — Sooloo Sea, 
East Indies. — Exp. Exp. 
10. PoRiTEs LEVIS {Dana). Cespitose, alive for 6 inches or more; 
branches long, furcate, subterete, scarcely compressed, irregularly inflated, 
below l-li inches thick, obtuse at apex and 3 to 4 lines broad ; polyps very 
short, brown ; tentacles minute, with whitish tips. Corallum rather firm, sur- 
face smooth ; cells wholly superficial, scarcely distinguishable. 
Plate 54, fig. 5, part of zoophyte, natural size ; 5 a, 5 6, polyps, enlarged ; 
5c, surface, enlarged; 5rf, cross section, ditto. — Feejee Islands. — Exp. Exp. 
11. PoRiTES CYLiNDRicA {Dana). — Cespitose, alive for 1 to 2 inches; 
branches erect and very much crowded together, often coalesing, neatly cylin- 
drical, below ^ to f of an inch thick, often furcate at apex, and rounded ; 
branchlets 1 inch long and i an inch thick. Corallum rather firm; cells 
wholly superficial, indistinct. 
Plate 54, fig. 4, corallum of part of a clump, natural size.-™Feejee Islands (.^). 
•—Exp. Exp. 
