322 A MONOGRAPH OF THE 



32. Isodictya fucorum, Bowerbank. 



Halichondria fucorum, Johnston. 



parasitica, Montagu. 



Brit. Mus. Collection. 



Sponge. Sessile, amorphous ; surface even. Oscula small, 

 simple, dispersed. Pores inconspicuous. Dermal 

 membrane pellucid, sparingly spiculous. Tension 

 spicula acuate, same as those of the skeleton ; reten- 

 tive spicula simple bihamate, minute, dispersed, few 

 in number. Skeleton. In the young state sym- 

 metrical; in the older specimens very diffusive and 

 irregular ; primary and secondary lines both more or 

 less multispiculous. Spicula sub-fusiformi-acuate. 

 Interstitial membranes. . Tension spicula acuate, 

 slender, few in number. 



Colour. Alive, bright red or pink, to pale ash or brown. 



Habitat. Common on most parts of the British coasts : 

 Brighton, Mr. Thos. Ingall ; Burrafirth Caves, Shetland, 

 Rev. A. M. Norman ; Scarborough, Mr. Bean ; Hastings, 

 J. S. Bowerbank. 



Examined. Alive. 



My friend Mr. Ingall has found this species on the 

 Brighton coast in considerable quantities, and of a bright 

 pink colour ; the specimens agree in structure with the one 

 labelled " parasitic ' : in Montagu's collection of sponges, 

 but the label is written with pencil, and appears to be a 

 different handwriting from the rest of the labels. Montagu, 

 in the Wernerian Memoirs, vol. ii, p. 114, says " the tex- 

 ture is rather coarse, and the fibres fimbriated/'' whereas 

 in the specimen in his collection, and in all others that I 

 have examined of the same species, the texture is decidedly 

 fine and delicate, and there is no appearance of fimbriated 

 fibre. I am therefore inclined to believe that the specimen 



