166 BRITISH SPONGIADJ;. 



crimination, but these are characters upon which very 

 little dependence can be placed." 



6. Raehiodesma INTERMEDIUM, 5om;., n. sp., IV, Pl.XVII, 

 figs. 1 — 6. 



" Sponge incrusting roots of fuci, &c. ; surface un- 

 even but smooth. Oscula simple, minute. Pores incon- 

 spicuous. Dermal membrane spiculo-reticulated, rete 

 irregular, variable in the number of its spicula ; spicula 

 acuate, rather long and stout, same as those of the 

 skeleton ; retentive spicula bihamate, simple and 

 contort, large and numerous, and bidentate inequi- 

 anchorate, minute, and few in number. Skeleton 

 — fasciculi numerous, irregularly disposed, variable in 

 the number of their component spicula, bases and 

 apices of their spicula coincident ; spicula acuate, 

 rather long and stout ; tension spicula acuate, long, 

 and slender; retentive spicula same as those of the 

 dermis, but less numerous. 



" Colour. — Alive, scarlet ; dried, light ochreous 

 yellow. 



" Habitat. — Roundstone Bay, Ireland, on roots of 

 Laminaria ; Rev. A. M. Norman. 



" Examined. — From spirit. 



" I received from my friend the Rev. A. M. Norman 

 two small portions of the root-like base of a Laminaria 

 covered by a thin incrustation of sponge, the colour of 

 which when alive is stated to have been ' scarlet,' 

 but when dried was of a light ochreous colour. I 

 could not detect the oscula by the aid of a lens of two 

 inches' focus, though they became visible as small simple 



