108 BRITISH SPONGIADJil. 



tension spicula subfusiformi-cylindrical, long and 

 slender, numerous, more or less fasciculated or dis- 

 persed ; retentive spicula bihamate, simple and con- 

 tort, numerous, variable in size ; and bidentate equi- 

 anchorate, and. rarely palmato-inequi-ancliorate. Os- 

 cula simple, dispersed. Pores inconspicuous. Skele- 

 ton rete irregular; spicula fusiformi-acuate, stout 

 and moderately long. Interstitial membranes spiculous, 

 tension spicula rarely present ; retentive spicula same 

 as those of the dermal membrane, numerous. 



" Colour. — In the dried state, dark brown. 



"Hadifat. — Westport Bay, Ireland, 5 fathoms ; Rev. 

 A. M. Norman. 



" Examined. — In the dried state. 



" I received a single specimen of this species from my 

 friend the Rev. A. M. Norman for examination. It 

 completely fills the interstices of a mass nearly two 

 inches long by one in breadth of a specimen of Nulli- 

 pora polymorpha, and in some parts growing over the 

 apices of the branches and presenting a smooth sponge 

 surface to the eye. The surface is very minutely 

 hispid in the dried state, though both to the eye and to 

 the touch it appears to be smooth, and it is only when 

 a section of the sponge is made at right angles to the 

 surface and mounted in Canada balsam that the nume- 

 rous external defensive spicula become visible, and 

 even in this state very few comparatively pass through 

 the dermal membrane. These spicula rarely exceed 

 half the length of the skeleton ones, and they are much 

 more slender; they are usually only basally spinous, 

 but occasionally a few spines appear on various parts 

 of the shaft or near the apex, but these are rarely so 

 well developed as those of the base of the spiculum. 



