1869.] 395 [Verrill 



alternately large and small. The larger septa are very stout, much 

 thickened at the margin, tapering to a sharp edge within, the sides 

 and edge roughly granulous ; the costal part is very prominent, thick, 

 but less so than the marginal jiart, sharp edged, and almost always 

 continuous with one of the large septa of an adjacent cell. The 

 alternating small septa are not more than half as wide, thin, much 

 less prominent, slightly thickened at the margin, and extend, as thin, 

 costal lamellse between the much thicker and more prominent pri- 

 mary ones, to adjacent cells, but they are often interrupted and vari- 

 ously branched. Stout trabiculae are often visible at the surface 

 between the costal lamellae. Columella represented by a small central 

 tubercle, which is often wanting, and a deeper, large, solid portion, 

 which fills the centre of the cell below, and unites with the inner 

 edges of the septa. Endotheca represented by distinct, regular, thin, 

 nearly horizontal, transverse septa, as In many Astrajans. These are 

 about .03 to .0.5 inch apart in the same interseptal chamber, as seen 

 In a vertical section. The radiating sejjta are solid and continuous. 



The largest specimen is nearly three feet long, two feet broad, and 

 eight inches thick in the middle; diameter of cells mostly .08 to .12 ; 

 distance between them, in the direction of the costal plates, generally 

 .10 to .16. 



Pearl Islands ; brought from seven fathoms by ]\Ir. Clarke, a pearl 

 collector; F. H. Bradley. 



Pavonia clivosa Verrill, sp. nov. 



Corallum thick and massive, lobate, or rising into very large 

 rounded eminences or oblong ridges, thickly covered with stellate 

 cells, which are smaller and nearer together than in the preceding 

 species. Cells mostly uniformly scattered, often closely crowded and 

 contiguous on the summits of the prominences, usually separated on 

 other parts at distances about equal to their own diameter. Septa 

 generally from sixteen to twenty-four, alternately larger and smaller; 

 the larger ones rather thin, but little thickened, even at the margin, 

 roughly granulous on the sides; their costal prolongations elevated 

 and rather thin. Smaller septa about half as wide, a little thinner 

 and less elevated, as are also their costal proloTigations. Columella a 

 small tubercle, often prominent, sometimes flattened. Internal struc- 

 ture as In the preceding, but the transverse septa are nearer together. 



The largest specimens are ten Inches to two feet In diameter ; and 

 often a foot thick or high ; some of the prominences or lobes are from 



