TRIBE I. ASTR^ACEA. 
33 
41. Astr^a petrosa {Dana). — Convex. Corallum subcellular, firm: in 
a transverse section, the stars orbiculate, commonly oblong, li to 3 lines 
broad, and to 5 lines long, many-rayed, rays very thin, with the cellules 
simple ; septa a line thick and quite solid. 
Plate 12, fig. 12 a, transverse section of corallum, natural size ; 12 &, verti- 
cal section of same. 
42. AsTRiEA PURPUREA {Dana). — Hemispherical; polyps half an inch 
broad, disks bright-green, tentacles numerous, purple. Corallum subcellular, 
firm ; cells angular, rather shallow ; 4 to 5 lines broad, not coronate within ; 
ridges triangular, very delicately sulcate ; lamellge crowded, even, very finely 
denticulate, nearly entire, and but slightly prominent at apex : in a transverse 
section, stars nearly circular, many-rayed, cellules simple, very narrow ; septa 
solid, cellules rare and very minute. 
Plate 12, fig. 10, natural size; 10a, cells, do.; 106, profile of cell and la- 
mellae, enlarged; 106^, same, natural size; 10c, vertical section, enlarged; 
10c?, same, natural size; 10 e, transverse section, enlarged four diameters, 
from a part of the corallum where the cells were small. — Feejee Islands.— 
Exp. Exp. 
43. Astr^a pulchra {Dana). — Convex ; umber-colored, top of ridges 
pale, tentacles brown. Corallum subsolid, firm ; cells angular, unequal, mostly 
3 to 4 lines broad, rather shallow, not coronate within; ridges triangular, en- 
tire, lamellae even, crowded, thin, nearly entire, but little prominent over the 
septum : in a transverse section, stars many-rayed, with the cellules simple : 
septa quite solid : in a vertical section cellules under the star very minute. 
Plate 12, fig. 1], polyps partly expanded, natural size; 11 a, polyp enlarged ; 
116, section of cells, showing outline of lamellaa, enlarged two diameters ; 
11c, same, natural size; 11c?, vertical section of corallum, enlarged; lie, 
same, natural size ; 1 1/, transverse section of corallum, enlarged three diam- 
eters. — Feejee Islands. — Exp. Exp. 
44. AsTRiEA PENTAGONA {Espcv,) Ehrenhevg. — Semiglobose. Corallum 
with the cells angular, usually pentagonal, 44 to 5 lines broad, unequal, some- 
times oblong, neatly coronate within, a columnar appendage at centre; ridges 
narrow, obtuse, or subacute. — East Indies. — Esper. 
45. AsTRiEA FAVisTELLA {Dana). — Subhemispherical. Corallum cellular, 
rather light; cells neatly angular, rather shallow, mostly 3 to 4 lines broad, 
coronate within ; ridges about a line thick, entire. Gothic, subacute; lamellse 
subentire and very even, abrupt within : in a transverse section, stars scarcely 
many-rayed, with the cellules simple ; septa not half a line thick, with very 
minute cellules, uniseriate, sometimes obsolete. 
5 
