TRIBE I. ASTR-iEACEA. 213 



Erect glomerate and gibbous, 5 inches high and 2 broad; polyps 

 small (scarcely 2 lines broad), with 24 internal lamellae. Corallum 

 firm ; cells circular, scarcely 1 J lines broad ; margin a little promi- 

 nent, with 24 subequal denticulate lamellae ; interstices usually a 

 line broad : in a transverse section, stars about 24-rayed ; septa 

 sparingly cellular, pellules sometimes uniseriate. 



Plate 10, fig. 16, transverse view, natural size. 



West Indies. Bost. Nat. Hist. Soc. 



The erect mode of growth of this species is somewhat like the 

 last, but the texture is more solid and the rays of the star less delicate 

 and even. Only a worn specimen has been seen by the author. In 

 this the interstices are flat or slightly concave, and have very faint 

 radiated strise. The lamellae of the cells barely meet in the centre. 

 This species differs from the stellulata and annularis in having the 

 twelve intermediate lamellae of the star nearly as prominent as the 

 others; hence in a transverse section, about twenty-four rays may be 

 distinguished in the larger cells. In a vertical section the transverse 

 dissepiments are quite oblique, and occasionally the cellules of the 

 stars in a transverse section are subdivided by them. 



10. A. ORBICELLA PLEIADES. (Ellis.) 



A. convexa, polypis lj'" latis, lamellis 24. Corallum percelluhsum, 

 debile ; cellis orbiculatis,fere !"' latis, margine annulate, tenuissimo ; 

 interstitiis concavis, laxe cellulosis, angustis ("') : transverse secto, 

 lamellis duodecim tenuissimis, aliis intermediis obsoletis. 



Convex ; polyps 1 J lines broad, with 24 internal lamellae. Corallum 

 very light and delicately cellular; cells orbiculate, nearly l lines 

 broad, margin annular and very thin ; interstices concave, loose 

 cellular, narrow (about J of a line) : in a transverse section, lamella? 

 12, very thin, the intermediate obsolete. 



Plate 10, fig. 5 a, transverse section, natural size; 5 b, same en- 

 larged ; 5 c, vertical section, natural size. 



East Indies. Ellis, Lamarck. Wake's Island, Pacific Ocean. 

 Exp. Exp. 



54 



