356 Verrill, Notes on Radiata. 



to "7 of an inch, irregular, polygonal, often an inch in length and 

 containing two or three centers, moderately deep ("IS inch), with a 

 small, depressed center. Columella rudimentary or slightly devel- 

 oped, of loose convoluted processes. Septa in five cycles (the last im- 

 perfect), rather thin, slightly thickened outwardly, the summits pro- 

 jecting stibequally (about '05 inch), the upper part divided into from 

 three to five sharp, elongated, unequal teeth ; the lower part unevenly 

 serrate, and presenting usually a distinct, broad, paliform lobe, which 

 is strongly serrate. Between the cells the wall is often double, with 

 vesicles between, but it is also frequently simple and nearly solid. 

 Color of unbleached coral deep umber. Diameter of some of the 

 masses upward of a foot. 



This is one of the most abundant corals at the Abrolhos Reefs, 

 and on account of its large size and solidity, doubtless one of the 

 most important entering into their structure. 



Rare in tide-pools at the Abrolhos, and usually only in the deeper ones on the edges 

 of the reef, never in stations uncovered at low tide. Very abundant on the submerged 

 borders of the reefs in the AbroUios region, at Porto Seguro, Sta. Cruz, Bahia, Maceio. 

 At the Island of Sta. Barbara and on the Recife do Lixo, it grows in large sub-spherical 

 masses, on the edge of the reef, from a few inches below low-tide level to a depth of 

 15 or more feet. Some of the corals are two feet or more in diameter. In the water 

 they have a pale grayish tint. — c. f. ii. 



Heliastraea aperta Verriii, sp. nov. 



Corallum forming large rounded masses, a foot or more in diameter, 

 of rather light, open texture. Cells circular, large (about "3 of an 

 inch), moderately deep ("1 inch), with a broad central area, the mar- 

 gins projecting about "08 of an inch above the general surface ; septa in 

 three complete cycles, narrow, thin, subequal, the summits consider- 

 ably projecting, angular, acute, the inner edges nearly perpendicular, 

 finely toothed, often with a distinct paliform tooth at the base. Col- 

 umella well developed, of loose open tissue. Costse elevated and 

 thin, rising obliquely upward to the summits of the septa, finely ser- 

 rate. Walls very thin, inconspicuous. In a vertical section the 

 columella is large, composed of loosely reticulated, convoluted and 

 often fenestrated, lamelliform processes, with large irregular cells 

 between. Tlie cells of the endotheca are mostly simple, broader than 

 high, inclining slightly downward, formed by very thin lamellae. 

 The cells of the exotheca are larger, more irregular, alternately over- 

 lapping, often compound, about as high as broad, formed by stouter 

 lamellte, which curve downward. W alls very thin, but continuous. 

 Septa longitudinally roughened, scarcely granulated. Color of the 

 unbleached coral dull umber-brown. 



