134 A MONOGEAPH OP THE 



skeleton, variable in size. Interstitial membranes. 

 Tension spicula fusiformi-acerate, not very numerous ; 

 with a few skeleton and defensive ones intermixed. 

 Retentive spicula bidentate angulated equi-ancho- 

 rate, minute, uniform in size, very numerous. 



Co/owr.— Alive, orange-red. 



Habitat. — Sennen Cove, Land's End, Cornwall, and 

 Diamond Ground, off Hastings, J. S. Bowerbank; Bantry 

 Bay, Ireland, Guernsey and Polperro, Rev. A. M. Norman. 



Examined.-^ In both the fresh and dried states. 



I found this species adhering to the blocks of granite, 

 somewhat protected from the full action of the sea near low 

 water mark, under the point at the south side of Sennen 

 Cove, near the Land's End, Cornwall, on the 6th of May. 



The largest specimen was about two inches in diameter 

 and half an inch in thickness, and of a deep orange-red 

 colour. In the living condition the surface was smooth 

 and even, but in the dried state corrugated or slightly mam- 

 millated. No oscula were visible in the living sponge. 



The dermal membrane is pellucid, and is furnished 

 abundantly with large fusiformi-acerate spicula, which are 

 dis])ersed or loosely fasciculated. The skeleton columns 

 are long, slender, and often flexuous, and frequently give 

 off short, simple branches, which I have never observed to 

 bifurcate, or to give off secondary branches, and they 

 usually terminate like the primary columns in a cluster of 

 defensive spicula, which radiate in every direction. The 

 skeleton spicula are disposed on the surfaces of the columns 

 and in accordance with the axis ; they are longer than the 

 defensive ones, and more inclined to be regularly acuate. 

 The defensive spicula are decidedly attenuato-acuate, they 

 vary considerably in size. They are very numerous, and 

 are disposed on the column at all angles to its axis. One 

 of these sponges is permeated by some small tubular 

 zoophyte, which it has coated with its own tissues, and 

 from these adopted columns defensive spicula are projected, 

 in a similar manner to those of the columnar skeleton. 



