492 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



of the large surfaces. The mass is excavated by large passage?, 

 which pass through the body and are 10-20 mm. in diameter on the 

 exposed surface, much larger over the attached surface. Dermal 

 membrane of the attached surface pale and smooth, with only a 

 few feeble conuli scattered here and there. On the exposed surface 

 the conuli are strongly but variously developed, and there is 

 a tendency for the sponge to grow out in the shape of irregular lobu- 

 lar elevations, between which the dermal membrane is comparatively 

 smooth. 



The character of the exposed surface with respect to the conuli 

 is, as said, variable. The indication is that it alters with growth, 

 and that the above mentioned lobular elevations are regions of 

 growth. On this assumption it becomes possible to understand and 

 describe the surface appearance. I pick out a number of conditions 

 which I believe represent stages in growth change. 



The particular surface condition, which is probably most charac- 

 teristic of the species, exhibits no lobes. Instead we find elevations 

 3-5 mm. high, marked with several, sometimes numerous, prickles. 

 Such elevations may be called compound conuli. They are mostly 

 10-15 mm. apart, measuring from the center of one elevation to that 

 of the next, and are connected by prominent ridges, which divide the 

 sponge surface into large, smooth, depressed areas. The prickles 

 on the compound conuli may be styled simple conuli. Similar ones 

 are found here and there on the ridges connecting the compound 

 conuli. The compound conulus begins as (1) a simple conulus. 

 In proof of this we find on the ridges not only simple conuli but (2) 

 somewhat larger, and yet similar, elevations divided at the summit 

 into two, three, or a few prickles, all close together. As such eleva- 

 tions grow they move apart and become (3) the compound conuli 

 of the characteristic surface condition. If now a compound conulus 

 becomes a spot of active growth, it becomes (1) more or less flat- 

 tened at the top, the simple conuli moving apart from one another, 

 but remaining connected by ridges. The flat-topped compound 

 conulus increases in size and becomes (5) a small projecting lobe 

 bearing simple conuli about 2 mm. apart, all interconnected by 

 ridges. Such lobes increase in size and the simple conuli shift 

 farther apart, so that (0) a well developed lobular projection re- 

 sults, bearing simple, sharp conuli 1-2 mm. high, -1-5 mm. apart, 

 interconnected by ridges. Such lobular projections, where they are 

 well developed, are separated by depressed areas of smooth mem- 

 brane, 10-15 nun. wide. Conditions (3) and (<>) differ much in 

 appearance. 



A few large oscula, 10-15 mm. in diameter, are found at one end 

 of the sponge. They lead into shallow depressions into which a 



