TRIBE I. ASTR^ACEA. 251 



Globose. Corallum, with cells 3J lines broad, often pentagonal, some- 

 what shallow, lamellae of contiguous stars continuous, sometimes 

 alternate, interstices none. 



The Red Sea. 



This species, according to Ehrenberg, is near the Hemprichii, but 

 has smaller cells and lamella more delicately toothed. 



Astrcea halicora, Ehrenberg, op. cit. G. Ix. sp. 10. 



60. ASTR^A CYCLASTRA. (Dana.) 



A. flexuoso-convexa, polypis 3-5'" latis. Corallum ceUulosum ; cettis 

 orbiculatis, margine prominulis et collibus scepius sukatis: transverse 

 secto, stettis multiradiatis, radiis 24-30 tenuibus, cellulis parce decom- 

 positis ; septis 1'" crassis, medio cellulosis, cettulis 1-2-seriatis. 



Flexuoso-convex, polyps 3 to 5 lines broad. Corallum cellular, cells 

 circular, margin a little prominent and ridges usually sulcate : in a 

 transverse section, stars many-rayed (24-30), rays thin, with the 

 cellules sparingly decompound; septa J to 1 line thick, cellular 

 along the middle, cellules in 1 or 2 series. 



The round cells resemble those of the Orbicellae, and they have an 

 oblique position, nearly as in the coronata ; but, although closely 

 allied to that division of the genus, it multiplies generally by disk- 

 buds. In a worn specimen in the cabinet of Prof. C. U. Shepard, of 

 New Haven, the cells are shallow tubes, one and a half to two lines 

 deep, the lamellae being worn off within. The convoluto-porous 

 centre at bottom occupies about half the whole breadth ; the lamellae 

 are very thin, and about twenty-four extend to the porous centre. 

 In a vertical section the texture, though firm, appears very cellular ; 

 the transverse dissepiments on the lateral surface of a lamella are 

 oblique, quite regular, and three or four to a line in length ; the tex- 

 ture of the middle of a cell is minutely and irregularly porous ; the 

 cellules of the septa are distinct, and generally in a single vertical 

 series. In a polished transverse section, the cellules are narrow, sur- 

 rounded by a nearly solid ring, about a quarter of a line thick, and 

 are confined to the middle of the septum. 



