644 Verrill, JSFotes on Radiata. 



distance, and in the latter case contiguous laterally, but the rows are 

 separated by spaces equal to once or twice the diameter of tlie cells, 

 which are united by very prominent septo-costal lamellte. In the 

 largest cells there are usually twenty-four septa, in three regular cycles, 

 often twelve, sometimes only eight or ten, and frequently irregular 

 numbers, between twelve and twenty-six, but in all cases they are 

 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 part, 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 mai'gin, and extend as thin 

 costal lamellie between the much thicker and more prominent primary 

 ones to adjacent cells, but they are often interrupted and variously 

 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 

 center of the cell below, and unites with the inner edges of the septa. 

 The endotheca consists of distinct, regular, thin, nearly horizontal, 

 transverse septa, as in many Astrseans ; these are about '03 to "05 of 

 an inch apart in the same interseptal chamber, as seen in a vertical 

 section. The radiating septa 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 'IG of an inch. 



Pearl Islands, — F. H. Bradley. 



It was brought from seven fathoms by Mr. Clarke, a pearl collector 

 who gave great assistance to Mr. Bradley while makiiig his collections. 



Pavonia Clivosa Verrill, op. cit., p. 395. 



Plate IX, figure 8. 



Corallum thick and massive, lobed, 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, only little thickened even at the margin, roughly granu- 

 lous on the sides ; their costal prolongations elevated and rather thin. 



