TRIBE I. ASTR^ACEA. 
5& 
4. Agaricia levicollis {Dana). — Broad explanate, a little undulate, thiB> 
j (1^ to 3 lines); ridges elongate, nearly obsolete, narrow (1 to 1^ lines). Co- 
rallum with the oririmes seriate, indistinct; under surface finely striate. 
! Plate 22, fig. 2, part of corallum, natural size. — East Indies. — Exp. Exp. 
5. Agaricia planulata {Dana). — Broad explanate, attached by a point 
I on the under surface ; thin (1^ lines) ; polyps either seriate or scattered. Co- 
I rallum with obsolete interstitial ridges, or with polygonal cells nearly superfi^ 
i cial, and 1 to 2 lines broad ; under surface concentrically and radiately faint 
; plicate, striae very fine and a little divergent. 
I Subgenus II. — MYCEDIA. 
I Surface with transverse or reticulate ridges ; fosste sometimes 
; long and even, but usually consisting of separate excavate cells, 
I clustered or seriate (cells sometimes distinct only along the foss^ 
; near the margin). Coralla very compact. 
1 
I. Unifacial. 
6. A. Mycedia cucullata {Ellis,) Oken. — Unifacial, stipitate, subturbin 
ate ; fronds often convoluted and coalescing at base ; above concave, with 
transverse ridges subflexuous and irregular, and frequent deep cells inter- 
spersed. Corallum very firm and compact, below very finely striate. 
West Indies. 
7. A. Mycedia purpurea {Lesueur). — Foliaceous, unifacial, for the most 
part incrusting, concave above and undulate, with deep cells arranged either 
in series or irregularly grouped, and the surface therefore irregularly or re- 
ticulately colliculate ; polyps with the tentacles obsolete ; lip yellowish, and 
disks with yellow rays. Corallum with the margin acute ; below finely striate 
and concentrically undulate. 
St. Thomas, West Indies. — Lesueur. 
8. A. Mycedia fragilis [Dana). — Unifacial, stipitate, broadly explanate, 
and somewhat hypocrateriform, very thin; polyps small, mostly in series, 
which are separated by even ridges 1^ lines broad. Corallum with the mar- 
gin subpapyraceous, and, for a considerable breadth, translucent and quite 
fragile; fossse scarcely f of a line deep, and often near the margin composed 
of seriate calicles; cells (oririmes) f of a line broad; under surface very 
finely striate and concentrically undulate. 
West Indies. — Dost. Soc. Nat. Hist. 
II. Gtomerate, but explanate at base. 
9. A. Mycedia gibbosa [Dana). — Coarse gibboso-glomerate and angular, 
below broad planulate, sparingly undulate, and stipitate at centre ; polyps often 
