266 A MONOGRAPH OF THE 



on the substances on which the sponge may happen to be 

 based. The specimens were labelled " Colour, light 

 yellow." 



I have dedicated this interesting species to Mr. Geo. 

 C. Hyndman, of Belfast, who in conjunction with my late 

 lamented friend Mr. Win. Thompson, has done so much 

 to diffuse a taste for Natural History in Ireland, and to 

 whom also, I am indebted for much valuable information 

 and assistance regarding the Irish specimens of the 

 Spon giadae. 



25. Halichondria nigricans, Boiverbank. 



Sponge. Massive, sessile, compressed ; surface uneven, 

 somewhat rough. Oscula small, simple, nume- 

 rous. Pores inconspicuous. Dermal membrane thin, 

 pellucid ; furnished with terminally spined sub-fusiform 

 cylindrical spicula, irregularly disposed in fasciculi, 

 and with palmato-iiiequi-anchorate, dentato-inequi- 

 anchorate, and sparingly with minute inequi-bipocil- 

 lated spicula. Interstitial membranes furnished with 

 the same spicula as those of the dermal membrane. 

 Skeleton. Spicula acuate, entirely spined, stout. 

 Sarcode abundant, dark- coloured, abounding in com- 

 pressed cytoblasts or cells. 



Colour. Alive and dried very dark purple. 



Habitat. Orkney (?) or Hebrides (?), Mr. McAndrew ; 

 Strangford Lough, Professor Dickie ; Plastings, J. S. Bower- 

 bank. 



Examined. In the living and dried states. 



The specimen upon which this species is based is but a 

 fragment. I found it among a large quantity of specimens 

 of zoophytes, sponges, and other marine animals in the 

 possession of my friend Mr. McAndrew, at Liverpool, who 

 stated that they were part of the results of his dredgings 

 near the Orkney Islands and the Hebrides. It is one inch 



