324 DR. J.S. BOWERBANK ON THE SPONGIAD.E. [Mar. 18, 



attenuato-expando-ternate, rarely patento-ternate ; radii short and 

 stout, occasionally cylindrical. Interstitial membranes — tension- 

 spicula acerate, small and slender, few in number, and tuberculated, 

 subcylindrical, the same as those of the dermal membrane. Reten- 

 tive spicula : attenuato-stellate, radii spinous ; cylindro-sphero- 

 stellate, radii spinous ; and cylindro-sphero-stellate, radii short and 

 spineless. 



Colour, in the dried state, ochreous yellow. 



Hab. Fiji Islands (Sir Everard Home). Museum Royal College 

 of Surgeons. Catalogue of Porifera, part i. 1860, p. 127, B. 1/1. 

 Examined in the dried state. 



This sponge, 2| inches in height and 2 inches greatest diameter, 

 is massive but inclined to be cyathiform, and it has apparently been 

 attached by its base to a small oval pebble. In the dried condition, 

 the ternate heads of the connecting-spicula project beyond the 

 surface of the dermal membrane, imparting an asperated sensation 

 to the touch ; this character, it is probable, would not exist in the 

 living sponge. 



In consequence of the destruction of the greater part of the 

 dermal membrane, the oscula are not very readily to be distin- 

 guished ; but the few that are apparent are small and simple in their 

 structure. 



The dermal membrane, when mounted in Canada balsam and 

 examined with a power of 160 linear, appears almost opaque 

 from the profusion of the tuberculated subcylindrical spicula with 

 ■which it is furnished ; they are irregularly but very closely packed 

 in a single stratum on its internal surface ; an average-sized one 

 measured, length -^Ta i ncn > diameter T5 Vo inch. When exceeding 

 the ordinary size, they are frequently somewhat fusiform. 



The skeleton-spicula are irregular in their size and proportions, 

 and frequently have a sudden decrease of diameter at the distal 

 termination two or three times their own diameter from the apex ; 

 and sometimes this contraction may be observed at both terminations 

 of a spiculum. 



The retentive spicula of the interstitial membranes afford excellent 

 specific characters. The attenuato-stellate ones have their radii 

 always more or less spinous : sometimes their apices only are thus 

 armed ; but in their fully developed state the spination extends over 

 every part of them. There are two distinct forms of cylindro- 

 sphero-stellate spicula : — one in which the central sphere is com- 

 paratively small, and which has the cylindrical radii spinous ; the 

 other in which the central sphere is largely produced, and the 

 cylindrical radii are perfectly smooth. These varieties of sphero- 

 stellate spicula are perfectly distinct and permanent, and never 

 appear to graduate into each other. These stellate forms are very 

 abundant, but they are not readily to be detected in situ without the 

 section being immersed in Canada balsam, in consequence of the great 

 density of the sarcodous tissues. They are mixed together and are 

 irregularly dispersed on the interstitial tissues; and along with them 



