172 BRITISH 



of the sponge in the form of cylindrical branching- 

 tubes, are bathed in the great sarcodous mass. 

 Skeleton spiculo-fibrous, irregularly reticulated ; fibres 

 polyspiculous, the primary lines (especially of the 

 fistula?) of great size. Spicula acerate, stout (Bower- 

 bank, Vol. I, PI. I, fig. 2), and very minute, in the 

 form of half a ring, * simple bihamate ' (Bowerbank^ 

 Vol. I, PI. V, fig. 109). Dermal membrane reticulate, 

 rete for the most part unispiculous, spicula of the 

 same two kinds as those of the skeleton. 



" Oceanapia Jeffteysii (Bow.)=Desmacidon Jeffreys* h' 9 

 Bow., 'Brit. Spongiada?,' Vol. II, p. S4<7 ==Isodictya 

 robusta, id., ib., p. 304. 



"In 1861 I dredged a portion of the spherical 

 crust of the sponge, from which the fistula? had been 

 abraded. This having been placed in Dr. Bower- 

 bank's hands, was considered by him to belong to the 

 genus Isodictya, and is described in his work under 

 the name I. robusta. In subsequent expeditions to 

 Shetland I obtained many detached fistula?, and also 

 portions of the crust, which convinced me that the 

 entire sponge, when found, would prove to be some- 

 thing very different from what had been imagined by 

 Dr. Bowerbank from the type specimen. In 1864 

 some of the fistula? were forwarded by Mr. Peach to 

 Dr. Bowerbank, who regarded them as a new species 

 of Desmacidon (D. Jeffrey sii). At length during the 

 past summer several perfect specimens of the sponge 

 have been dredged, and it is thus proved to be a 

 remarkable species, perhaps the most interesting, as 

 it is also one of the largest of British Porifera. 



" In form and size the adult sponge most strikingly 

 reminds us of a full-grown swede turnip. Imagine 



