260 A MONOGRAPH OP THE 



membrane pellucid, furnished abundantly with large 

 fusiformi-cylindrical tension spicula terminally spined, 

 loosely fasciculated or dispersed, as long as those of 

 the skeleton : also abundantly with simple bipocillated 

 anchorate spicula, and sparingly with dentato-palmate 

 and bidentate inequi-anchorate spicula. Skeleton. 

 Spicula fusiformi-acuate, basally and apically spined, 

 stout. Interstitial membrane. Tension spicula same 

 as those of dermal membrane, very abundant, dis- 

 persed ; also with simple bipocillated, dentato-palmate 

 and bidentate inequi-anchorate spicula sparingly. In- 

 ternal defensive spicula, acuate, entirely spined, short 

 and stout, very few in number. 



Colour. — Alive, vivid greenish blue. Nut-brown when 

 dried. Rev. A. M. Norman. 



Habitat. — Shetland, Rev. A. M. Norman. 

 Examined. — In the dried state. 



This sponge is parasitical on a slender branching Zoophyte 

 running over every part of it and coating the branches to 

 the thickness of about a line, the entire diameter rarely 

 appearing to exceed two lines ; where the dermal membrane 

 was preserved, the surface appeared smooth and even. 

 The large fusiformi-cylindrical tension spicula are veiy 

 abundant in some portions of the dermal membrane, fre- 

 quently completely covering a considerable space, arranged 

 in parallel order, or in broad flat fasciculi. The simple 

 bipocillated anchorate spicula were exceedingly numerous 

 in some parts of the inner surface of the dermal mem- 

 brane and a few contort and umbonated forms were mingled 

 with them. The pocillated anchorate spicula were many 

 of them attached to the membrane by the middle of the 

 back of the shaft, but the greater number were lying side- 

 ways. The interstitial membranes were very sparingly 

 furnished with these forms. The dentato-palmate inequi- 

 anchorate spicula are very irregular in their form. The 

 small basal end is remarkably angular, forming nearly an 

 equi-angular triangle, the lateral portions forming two of 



