‘TRIBE III.--MADREPORACEA» 
15 
to the margin ; tentacles 40, pale brown, in two series, the internal larger, ob- 
tuse, clavate ; visceral lamellse 32 in number. 
Red Sea . — Ehrenherg 
10. Palythoa cjesia {Dana). — Convex; color umber; polyps, when con- 
tracted, 4 to 6 lines broad ; disks umber-colored, except the centre, which is 
pale grayish-violet ; outer margin of the disks crenulate ; tentacles very nu- 
merous, in two series, umber-colored. 
Plate 30, fig. 3, and 3 a to 3 A. — Feejee Islands. — Exp. Exp. 
Tribe III.— MADEEPOEACEA. 
Actinaria witli tlie tentacles 12 in number (rarely more), in a 
single series, the alternate sometimes smaller: gemmiparous; 
gemmation inferior : coralligenous ; coralla calcareous, with the 
rays of the cells 6 to 12 in number or obsolete, interstitial sur- 
face not striated with the prolonged lamellae of the cells. 
The characteristics of the coralla in the several genera^ are as 
follows : 
Family I.~ MADREPORID^E. 
Cells deep and without cross septa. 
Genus 1. Madrepora. Branches with an apical calicle, and distinct late- 
ral calicles upon the branchlets. Cells deep, 6-12 radiating points within, 
which are sometimes obsolete. 
Genus 2. Manopora. No apical calicle; calicles all obsolete, or irregu- 
lar; coralla quite porous; cells as in the Madreporse. 
Family IL— FAVOSITIDiE. 
Cells with cross septa within the coralla ; rarely, solid below. 
Subfamily 1. ALVEOPORIN.E. Coralla very light porous ; cells deep, 
and with radiating points within, as in the Madreporas. 
Genus 1. Alveopora. Cells contiguous, with very thin cribrate parietes. 
Subfamily 2. FAVOSITIN^. Cells with radiating entire lamellEe, often 
becoming obsolete ; contiguous, at least at the summits of the coralla. 
