Grows in thin fronds or cups, not as small or deli- 

 cate as those of A. fragilis, but thinner than those of 

 Jl. agaricites. Cups on upper surface only. Under 

 surface covered with fine ridges. Chocolate to purple 

 brown in color. The cups are in small groups of three 

 or four. They are separated by walls which are strong- 

 ly inclined towards the edge of the frond, so that they 

 appear as if supported in brackets. As many as 48 

 septa in each cup. Cups about 4 mm across. Not 

 common. Florida reefs, the Bahamas and the West 

 Indies. 



Vedicelled with rounded, concave or flat fronds vary- 

 ing from i to 5 mm thick. Costal striae cover under 

 surface. Calices on upper surface in small groups of 3 

 to 6, separated by prominent, fairly short curved col- 

 lines set at an acute angle to the frond and facing to- 

 wards edge of the frond. Calices up to 5 mm, fairly 

 deep, with 3 6 to 4 8 finely serrulate septa. Septo-costae 

 about io mm. 

 10. Siderastrea radians (Pallas), (Plate 6). 



Described by Vaughan (1919), page 439. 



Corals form rounded or pebble shaped stones up to 

 1 foot or more across, but sometimes when young 

 forms encrustations. Grayish to brown in color. Cups 

 small, about ? mm and angular. Inner edges of septa 

 perpendicular, cavity of cup deep and narrow. Dis- 

 tinguished from S. siderea by smaller cup and deep 

 narrow cavity. Very common in shallow water in Ber- 

 muda, Florida, the Bahamas and the West Indies to 

 South America and Colon. 



Spheroidal or hemispherical masses up to 500 mm 

 diameter. Often encrusting or irregular when young, 

 or loose on bottom. Cerioid. Calices 2.5 to 3.5 mm, 



78 



