PLATE LXXII. 191 



HYMENIAOIDON PLUMIGER, Bowerlank. 

 Plate LXXII. 



Sponge sessile, coating. Surface even, smooth, or 

 slightly corrugated. Oscula slightly elevated and 

 conical ; margins thin, dispersed. Pores inconspi- 

 cuous. Dermal membrane abundantly spiculous ; 

 spicula disposed in flat featherly elongated bundles, 

 curving irregularly ; spicula of the fasciculi numerous, 

 acuate, not quite so long as those of the skeleton. 

 Skeleton abundantly spiculous ; spicula acuate, long, 

 and rather slender, very variable in diameter. 



Colour. In spirit dark olive-green. 



Habitat. Off Guernsey ; Mr. W. Saville Kent. 



Examined. From spirit, in the condition in which 

 it came from the sea. 



I am indebted to Mr. "W. Saville Kent for my know- 

 ledge of this sponge, which he obtained while dredging 

 off the Island of Guernsey in the yatch Norma in the 

 summer of 1870. The dimensions of the specimen 

 are one and a quarter inch in length, an inch in 

 breadth, and three lines in thickness. The oscula are 

 about ten in number, and nearly at equal distances 

 from each other ; they are slightly conical, and their 

 margins are very thin and somewhat irregular. 



The derniis of this sponge affords the most valuable 

 distinctive characters. The dermal membrane is thin 

 and translucent. It is abundantly furnished with 

 numerous, slightly-curving, fasciculi of continuous 

 series of spicula; from the surfaces of the bundles, spi- 

 cula are projected at slight angles towards their distal 

 extremities, where they radiate more or less in a fan- 

 shaped manner, giving to the flat fasciculi an appear- 

 ance very like that of a small wet feather. 



The skeleton is abundantly spiculous. The spicula 

 are regularly acuate, of the same form as those of the 

 dermis, but longer in their proportions, and, although 

 nearly all of equal length, they vary to a considerable 



