152 
SUPPLEMENT. 
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Genus MAEGIKOPOEA.— Quoy & Gaymard. ^ 
Free; very tliin disk-shape, circular. Coralla nearly plane 
above and below, and concentrically faint striate ; margin mi- 
nutely punctate ; internal texture concentrically cellular. 
Marginopora vertebralis (Q. ^ G.) — Plate 60, fig. 8. — Var. plicata, I 
figs. 9 a, b, h showing the interior structure. 
Genus POLYTEEMA.— Eisso. 
Small; incrusting or subramose, sometimes lacerato-subdi- ; 
vided. Coralla somewhat porous; surface punctate, and with ' 
scattered, minute, poriform cells, irregular, and having usually 
a lacerate margin, either immersed or at the summits of rounded 
or spiniform elevations. 
PoLYTREMA MiNiACEA. — Bright red; minute, and minutely ramoso-subdi- 
vided. 
Mediterranean Sea. 
PoLYTREMA BRUNNESCENS {Dana). Pale brownish ; thick incrusting, 
cavernous, surface gibbous, lacerate, and very irregular. 
Plate 61, fig. 3, natural size. — Society Islands. — Exp. Exp. 
PoLYTREMA MESENTERiNA {Dana). — Deep carmine, mesenteriform, con- 
sisting of suberect plicately aggregated laminse ; the margin minutely ragged 
or crispate, and furnished with a few scattered pores of irregular shape. 
Plate 61, fig. 4, natural size; 4a, portion enlarged, showing the character 
of the margin, — Tutuila, Navigator Islands. — Exp. Exp. 
