38-i A MONOGRAPH OF THE BRITISH SPONGIAD^E. 



granular character, which fills the whole of the thin horny- 

 looking shell or coat. The interstitial membranes are 

 thickly covered by sarcode, of a firm consistence, in which 

 there are often imbedded an abundance of nucleated cells, 

 varying in diameter from g^th to ^th of an inch. Amid 

 the numerous specimens of this sponge that have passed 

 through my hands, I have been unable to detect more than 

 one species ; although presenting every imaginable variety 

 in form, size, and colour, there were no permanent cha- 

 racters indicating an organic specific difference. 



Dr. Johnston, in his 'History of British Sponges,' page 

 190, describes, and in page 191 and plate xvi, figs. 6 and 

 7, figures, a second species of Dysidea, D. papillosa ; but he 

 expresses his doubts of its being truly a sponge, and his 

 belief that it was " the nidus of some invertebrated animal, 

 probably of a species of Natica." Since that period speci- 

 mens of the presumed D. papillosa have been found con- 

 taining the living animals, by the late Mr. Barlee, at 

 Shetland, and by Mr. Holdsworth, near Torquay, which 

 have been determined by Mr. Alder and Mr. Gosse to be- 

 long to the Zoanthidae, and Mr. Gosse has described them 

 in his 'Actinologia Britannica,' page 297, plate ix, figs. 9, 

 10; and plate x, fig. 5, as Zoanthus Couchii. 



